Based on a semester-long seminar on the topic, this book aims to fill a gap in the current engineering curricula by taking a wide-angle view at the process of engineering design rather than focusing on a more narrow and in-depth approach. As part of Artech House Publishers' technology management and professional development library, this is an excellent introduction to the topic and may serve for later reference.The author, Peter. H. Sydenham is the inaugural professor and head of the University of South Australia's School of Electronic Engineering, co-founder of the Australian Centre for Test and Evaluation, and a director of Global Systems Engineering Consulting Pty Ltd. This brief biographical sketch explains his qualification to write a book of such practical value and dimension, and why the book is pedagogically sound.The book, according to the preface, aims at those readers who are engineers "who have, or aspire to team leadership or want to take on increased team interfacing responsibilities". As such it builds on and expands what the author perceives to be too little taught in the regular university courses, and covers what is lacking: "breadth of the knowledge now needed to be an effective engineering designer."Twelve chapters offer a step-by-step introduction to the topic. The first chapter, "Systems Thinking and Systems Engineering", gives an overview and the "philosophical" background, while the last looks at "Change and Future Trends". The remaining ten chapters cover the practical aspects of the whole process of systems engineering design with a more hands-on approach, including basics of supporting knowledge such as staff management from planning over recruitment through training to promotion or termination of contract (chapter 3) or information technology support. As such, chapters 2–4 cover the more general aspects, while chapters 5–9 cover the design process from idea to evaluation. Chapter 10 intersperses legal issues, while chapter 11 covers the prototype build, i.e. the step from abstract design to material product.This is an introductory textbook, and as such, it does a very good job of the task at hand. The language is clear, the case examples are well chosen, and the message is conveyed without fail. Some issues are discussed somewhat at length; for example, the basic IT issues are explained in a very detailed way, but one might assume that the basics would be self-evident for today's user: the target audience will have grown up in the age of the personal computer and the internet and as such, will neither question the computer's usefulness nor be overly naïve with regards to the many IT bugs one has to deal with.The illustrations are about as clear as can be-some, in fact, are not clear at all but as they are meant to demonstrate the complexity of the issue at hand, the message gets conveyed the way it should be.How does this general book relate to the specialist field of biomedical engineering? To quote from p. 12: "Researchers in the life sciences were driven by a need to better understand how nature works and controls itself. Out of this pioneering work emerged general systems theory cybernetics, self-organizing systems, automation, automaton systems, organizational science, operations research, systems science, and more-topics with which engineers are not usually that familiar". This lack of familiarity becomes very evident when young engineers join research teams with a focus on applications for the life sciences, such as biomechanical engineering, but also within the broad field of bioinformatics, and they usually take more time to acquire and apply that holistic view of their work than life scientists need to acquire and implement detailed and circumscript engineering knowledge to accomplish their tasks. As such, this book can be recommended to engineers working in biomedicine even at the outset of their careers as it may draw their attention to the importance of this view of things in the new field they enter. Competing recent titles include works by Blanchard [ 1 ], Hitchins [ 2 ] and Sheridan [ 3 ]. A more general outlook on the importance of systems thinking in many areas of life, and far beyond engineering design, is Gharajedaghi's [ 4 ] modern classic.One point that a next edition seriously needs to address is the text editing. Using a word processor does not guarantee a perfect text: this one has a lot of extra words, and as many words missing. As faulty as the text editing is the punctuation check. These errors occur as often as once per page, and force the reader to repeat the study of entire paragraphs several times because, more often than not, it is the missing preposition or punctuation that poses a serious threat to understanding. The publishing house would do well in employing an old-fashioned human text editor to spare the reader such nuisance.In summary, this is a basic textbook to project design management for aspiring team leaders, not only in engineering but for any scientific and some business projects as well. Well written, this is a recommended introduction to the matter and may serve as a reference book and reminder even to the experienced team leader.Adrian Mondry is at Bioinformatics Institute, Singapore  Mondry@hotmail.com .Adrian Mondry is at Bioinformatics Institute, Singapore


Background Recent literature has called for humanistic care of patients and for medical schools to begin incorporating humanism into medical education. To assess the attitudes of health-care professionals toward homeless patients and to demonstrate how those attitudes might impact optimal care, we developed and validated a new survey instrument, the Health Professional Attitudes Toward the Homeless Inventory (HPATHI). An instrument that measures providers' attitudes toward the homeless could offer meaningful information for the design and implementation of educational activities that foster more compassionate homeless health care. Our intention was to describe the process of designing and validating the new instrument and to discuss the usefulness of the instrument for assessing the impact of educational experiences that involve working directly with the homeless on the attitudes, interest, and confidence of medical students and other health-care professionals.
Background
Recent literature has called for humanistic care of patients and for medical schools to begin incorporating humanism into medical education. To assess the attitudes of health-care professionals toward homeless patients and to demonstrate how those attitudes might impact optimal care, we developed and validated a new survey instrument, the Health Professional Attitudes Toward the Homeless Inventory (HPATHI). An instrument that measures providers' attitudes toward the homeless could offer meaningful information for the design and implementation of educational activities that foster more compassionate homeless health care. Our intention was to describe the process of designing and validating the new instrument and to discuss the usefulness of the instrument for assessing the impact of educational experiences that involve working directly with the homeless on the attitudes, interest, and confidence of medical students and other health-care professionals.Methods The study consisted of three phases: identifying items for the instrument; pilot testing the initial instrument with a group of 72 third-year medical students; and modifying and administering the instrument in its revised form to 160 health-care professionals and third-year medical students. The instrument was analyzed for reliability and validity throughout the process.
Methods
The study consisted of three phases: identifying items for the instrument; pilot testing the initial instrument with a group of 72 third-year medical students; and modifying and administering the instrument in its revised form to 160 health-care professionals and third-year medical students. The instrument was analyzed for reliability and validity throughout the process.Results A 19-item version of the HPATHI had good internal consistency with a Cronbach's alpha of 0.88 and a test-retest reliability coefficient of 0.69. The HPATHI showed good concurrent validity, and respondents with more than one year of experience with homeless patients scored significantly higher than did those with less experience. Factor analysis yielded three subscales: Personal Advocacy, Social Advocacy, and Cynicism.
Results
A 19-item version of the HPATHI had good internal consistency with a Cronbach's alpha of 0.88 and a test-retest reliability coefficient of 0.69. The HPATHI showed good concurrent validity, and respondents with more than one year of experience with homeless patients scored significantly higher than did those with less experience. Factor analysis yielded three subscales: Personal Advocacy, Social Advocacy, and Cynicism.Conclusions The HPATHI demonstrated strong reliability for the total scale and satisfactory test-retest reliability. Extreme group comparisons suggested that experience with the homeless rather than medical training itself could affect health-care professionals' attitudes toward the homeless. This could have implications for the evaluation of medical school curricula.
Conclusions
The HPATHI demonstrated strong reliability for the total scale and satisfactory test-retest reliability. Extreme group comparisons suggested that experience with the homeless rather than medical training itself could affect health-care professionals' attitudes toward the homeless. This could have implications for the evaluation of medical school curricula.

Background In 2003, the Department of Health and Human Services reported that there are between two to three million people in the United States who experience homelessness each year [ 1 ]. According to Gelberg and Arangua [ 2 ], such estimates provide only a partial picture of the problem: among the U.S. population, 14% (26 million people) have been homeless at some time in their lives and 5% (8.5 million people) have been homeless within the past five years. Yet even as this number grows, the homeless continue to be subjected to broad stereotyping and stigmatization, both of which make it easier to ignore them. It is not surprising then that homeless persons are reluctant to obtain needed, continuous medical care within traditional outpatient settings. This is particularly problematic because they often have competing or immediate needs [ 3 , 4 ], multiple health problems [ 5 , 6 ], and increased morbidity and mortality [ 7 , 8 ]. The disinclination of the homeless to seek care may be due in part to the way in which many health-care workers respond to them. A less investigated but possibly equally important circumstance is the attitudes that health-care professionals have toward the homeless. As members of the larger society, these professionals often harbor the same preconceived ideas and biases toward the homeless that the rest of society does. Such judgmental attitudes can, and often do, emerge during the provider-patient encounter, thus limiting the effectiveness of medical treatment of the homeless [ 9 ]. As a countermeasure to prevailing negative attitudes and widespread stigmatization toward marginalized persons, recent medical literature has drawn on a well-known practice in the social sciences [ 10 , 11 ] and has begun calling for greater emphasis on the dimensions of compassion and humanism in medical education [ 12 - 14 ]. Humanism in psychology became popular in the 1950s when Rogers [ 15 ] began practicing client-centered therapy, which allows the relationship between therapist and client to develop so that the client can be guided within the framework of the therapeutic encounter. According to Branch [[ 16 ], p. 1067], humanism in medicine may be defined as "the physicians' attitudes and actions that demonstrate interest in and respect for the patient, and address the patient's concerns and values." As physicians interact with homeless patients, a heightened sense of these patients' vulnerability may evoke greater empathy and humanism, two attitudes that can only have a positive impact on the quality of care that the physicians provide. Although it would be helpful to have a better understanding of physicians' current opinions about homeless patients, only two instruments have been designed and validated to measure attitudes toward homeless persons: the Attitudes Toward the Homeless Inventory (ATHI) [ 17 ], and the Attitudes Towards the Homeless Questionnaire (ATHQ) [ 18 ]. The ATHI surveys American college students' attitudes toward homelessness but does not specifically address the attitudes of health-care providers. In addition, it was not designed to measure a health-care provider's desire or confidence in his or her ability to deliver health care to homeless persons. Nevertheless, Buchanan et al. [ 19 ] recently used the ATHI to measure the attitudes of 12 primary care residents before and after a 2-week rotation in homeless health care and found that they felt more comfortable affiliating with homeless people after the course. The ATHQ, which was designed and validated in the United Kingdom, does assess the attitudes of health-care providers toward the homeless, but differences in health systems terminology (e.g., NHS for National Health Service, and terms related to homelessness, such as sleep rough) would make its use in its original form problematic in the United States. For this reason, we decided to use the ATHI for comparison purposes because its language is more consistent with American English. The purpose of our study was to develop and validate a new measure, the Health Professionals' Attitude Toward the Homeless Inventory (HPATHI), an instrument that could be used to assess United States medical students' and physicians' attitudes toward homeless persons and to measure their level of interest and confidence in their ability to deliver health-care services to the homeless population. The objectives of this study were to: 1) describe the process of designing and validating the new instrument, and 2) discuss the usefulness of the instrument for assessing the impact of educational experiences working with the homeless on the attitudes, interest, and confidence of medical students and other health-care professionals.
Background
In 2003, the Department of Health and Human Services reported that there are between two to three million people in the United States who experience homelessness each year [ 1 ]. According to Gelberg and Arangua [ 2 ], such estimates provide only a partial picture of the problem: among the U.S. population, 14% (26 million people) have been homeless at some time in their lives and 5% (8.5 million people) have been homeless within the past five years. Yet even as this number grows, the homeless continue to be subjected to broad stereotyping and stigmatization, both of which make it easier to ignore them. It is not surprising then that homeless persons are reluctant to obtain needed, continuous medical care within traditional outpatient settings. This is particularly problematic because they often have competing or immediate needs [ 3 , 4 ], multiple health problems [ 5 , 6 ], and increased morbidity and mortality [ 7 , 8 ].The disinclination of the homeless to seek care may be due in part to the way in which many health-care workers respond to them. A less investigated but possibly equally important circumstance is the attitudes that health-care professionals have toward the homeless. As members of the larger society, these professionals often harbor the same preconceived ideas and biases toward the homeless that the rest of society does. Such judgmental attitudes can, and often do, emerge during the provider-patient encounter, thus limiting the effectiveness of medical treatment of the homeless [ 9 ].As a countermeasure to prevailing negative attitudes and widespread stigmatization toward marginalized persons, recent medical literature has drawn on a well-known practice in the social sciences [ 10 , 11 ] and has begun calling for greater emphasis on the dimensions of compassion and humanism in medical education [ 12 - 14 ]. Humanism in psychology became popular in the 1950s when Rogers [ 15 ] began practicing client-centered therapy, which allows the relationship between therapist and client to develop so that the client can be guided within the framework of the therapeutic encounter. According to Branch [[ 16 ], p. 1067], humanism in medicine may be defined as "the physicians' attitudes and actions that demonstrate interest in and respect for the patient, and address the patient's concerns and values." As physicians interact with homeless patients, a heightened sense of these patients' vulnerability may evoke greater empathy and humanism, two attitudes that can only have a positive impact on the quality of care that the physicians provide.Although it would be helpful to have a better understanding of physicians' current opinions about homeless patients, only two instruments have been designed and validated to measure attitudes toward homeless persons: the Attitudes Toward the Homeless Inventory (ATHI) [ 17 ], and the Attitudes Towards the Homeless Questionnaire (ATHQ) [ 18 ]. The ATHI surveys American college students' attitudes toward homelessness but does not specifically address the attitudes of health-care providers. In addition, it was not designed to measure a health-care provider's desire or confidence in his or her ability to deliver health care to homeless persons. Nevertheless, Buchanan et al. [ 19 ] recently used the ATHI to measure the attitudes of 12 primary care residents before and after a 2-week rotation in homeless health care and found that they felt more comfortable affiliating with homeless people after the course. The ATHQ, which was designed and validated in the United Kingdom, does assess the attitudes of health-care providers toward the homeless, but differences in health systems terminology (e.g., NHS for National Health Service, and terms related to homelessness, such as sleep rough) would make its use in its original form problematic in the United States. For this reason, we decided to use the ATHI for comparison purposes because its language is more consistent with American English.The purpose of our study was to develop and validate a new measure, the Health Professionals' Attitude Toward the Homeless Inventory (HPATHI), an instrument that could be used to assess United States medical students' and physicians' attitudes toward homeless persons and to measure their level of interest and confidence in their ability to deliver health-care services to the homeless population. The objectives of this study were to: 1) describe the process of designing and validating the new instrument, and 2) discuss the usefulness of the instrument for assessing the impact of educational experiences working with the homeless on the attitudes, interest, and confidence of medical students and other health-care professionals.Methods The development and validation of the HPATHI occurred in three phases. The first phase consisted of the identification of items for the inventory; the second phase involved a pilot test of the initial instrument with a group of medical students; and the final phase entailed modifying the instrument and administering it in its revised form to our target population – health-care professionals, including primary care physicians, primary care residents, and third-year medical students. Throughout this three-phase process, we sought to ascertain the reliability and validity of the HPATHI. Three types of validity were tested. Content validity was evaluated using the Delphi technique [ 20 ], which seeks consensus on instrument items among a panel of experts. Concurrent validity was computed by correlating the target population's responses to the HPATHI with their responses to the ATHI. Construct validity was established by using the extreme groups method [ 21 ], by conducting an exploratory factor analysis, and by conducting item analyses to assess the relationship of each individual item to the instrument's overall scale and hypothetical subscales. Stages of development and validation of the HPATHI In Phase 1, a group of physicians and nurse practitioners, all experts in homeless health care, was recruited through snowball sampling [ 22 ] to serve on a Delphi panel [ 20 ]. These individuals were identified as experts because they work with the homeless on a regular basis and are members of the National Health Care for the Homeless Clinicians' Network. They received a list of statements about the homeless, homelessness, and homeless health care that was compiled by selecting and adapting appropriate items from the AHTI [ 17 ] and the ATHQ [ 18 ]. We, as the authors of this study, added additional items that were based on our experiences and our review of the literature. The experts were asked to classify the statements into one of three categories ("essential," "interesting but not essential," and "irrelevant") and to generate other items that they considered to be necessary to explore health-care professionals' attitudes toward the homeless. The panel reached a consensus on the items to be used in the instrument through successive rankings of the items. The statements were then combined into an instrument with a five-point Likert scale (1 = strongly disagree; 2 = disagree; 3 = neither agree nor disagree; 4 = agree; and 5 = strongly agree) organized around three thematic areas: a)  attitudes  toward the homeless; b)  interest  in working with the homeless; and c)  confidence  in one's ability to work with the homeless. During Phase 2, we administered the first draft of the HPATHI to a convenience sample of third-year medical students enrolled at Baylor College of Medicine (BCM) in Houston, Texas. These students were selected because they showed an interest in working with the homeless by registering for an elective course that allows students to provide health care to the homeless in a clinic setting [ 23 ]. Of the 100 students who attended class on the day that the instrument was administered, 72 completed it and were asked to provide contact information for the retest. Student responses to the instrument were analyzed using Cronbach's alpha coefficient to establish its internal consistency. Two weeks later, 34 of the 63 students who provided e-mail addresses completed the instrument a second time, thereby providing the data to determine the HPATHI's test-retest reliability. We then conducted an item analysis of redundant items or those with poor item-to-scale correlations. In Phase 3, we prepared Web-based versions of the HPATHI and of the ATHI and sent the Internet link to our target population with a standard invitation to complete both instruments. Primary care physicians who serve as faculty in the BCM Department of Family and Community Medicine, family practice residents in the BCM Department of Family and Community Medicine, general internal medicine residents in the BCM Department of Family and Community Medicine, and students from the BCM Medical School served as a convenience sample of individuals completing the instrument over a six-month period. Subsequent data analysis consisted of: 1. Conducting an exploratory factor analysis using a Promax rotation to examine the structure of the HPATHI. 2. Estimating the internal consistency reliability of the online version of the HPATHI using Cronbach's alpha coefficient; 3. Determining the concurrent validity of the HPATHI against the ATHI; 4. Comparing extreme groups on their responses to the HPATHI. The extreme groups were determined according to their level of training (preclinical medical students vs. physicians) and according to their experience in working with the homeless (<1 month vs. >1 year). This study was approved by the BCM Institutional Review Board for educational research with human subjects. Data analysis was conducted using SPSS Version 12.0 statistical software for Phases 1 and 2 and SAS ®  (V8.2 and V9.1) for Phase 3.
Methods
The development and validation of the HPATHI occurred in three phases. The first phase consisted of the identification of items for the inventory; the second phase involved a pilot test of the initial instrument with a group of medical students; and the final phase entailed modifying the instrument and administering it in its revised form to our target population – health-care professionals, including primary care physicians, primary care residents, and third-year medical students.Throughout this three-phase process, we sought to ascertain the reliability and validity of the HPATHI. Three types of validity were tested. Content validity was evaluated using the Delphi technique [ 20 ], which seeks consensus on instrument items among a panel of experts. Concurrent validity was computed by correlating the target population's responses to the HPATHI with their responses to the ATHI. Construct validity was established by using the extreme groups method [ 21 ], by conducting an exploratory factor analysis, and by conducting item analyses to assess the relationship of each individual item to the instrument's overall scale and hypothetical subscales.Stages of development and validation of the HPATHI In Phase 1, a group of physicians and nurse practitioners, all experts in homeless health care, was recruited through snowball sampling [ 22 ] to serve on a Delphi panel [ 20 ]. These individuals were identified as experts because they work with the homeless on a regular basis and are members of the National Health Care for the Homeless Clinicians' Network. They received a list of statements about the homeless, homelessness, and homeless health care that was compiled by selecting and adapting appropriate items from the AHTI [ 17 ] and the ATHQ [ 18 ]. We, as the authors of this study, added additional items that were based on our experiences and our review of the literature. The experts were asked to classify the statements into one of three categories ("essential," "interesting but not essential," and "irrelevant") and to generate other items that they considered to be necessary to explore health-care professionals' attitudes toward the homeless. The panel reached a consensus on the items to be used in the instrument through successive rankings of the items. The statements were then combined into an instrument with a five-point Likert scale (1 = strongly disagree; 2 = disagree; 3 = neither agree nor disagree; 4 = agree; and 5 = strongly agree) organized around three thematic areas: a)  attitudes  toward the homeless; b)  interest  in working with the homeless; and c)  confidence  in one's ability to work with the homeless. During Phase 2, we administered the first draft of the HPATHI to a convenience sample of third-year medical students enrolled at Baylor College of Medicine (BCM) in Houston, Texas. These students were selected because they showed an interest in working with the homeless by registering for an elective course that allows students to provide health care to the homeless in a clinic setting [ 23 ]. Of the 100 students who attended class on the day that the instrument was administered, 72 completed it and were asked to provide contact information for the retest. Student responses to the instrument were analyzed using Cronbach's alpha coefficient to establish its internal consistency. Two weeks later, 34 of the 63 students who provided e-mail addresses completed the instrument a second time, thereby providing the data to determine the HPATHI's test-retest reliability. We then conducted an item analysis of redundant items or those with poor item-to-scale correlations. In Phase 3, we prepared Web-based versions of the HPATHI and of the ATHI and sent the Internet link to our target population with a standard invitation to complete both instruments. Primary care physicians who serve as faculty in the BCM Department of Family and Community Medicine, family practice residents in the BCM Department of Family and Community Medicine, general internal medicine residents in the BCM Department of Family and Community Medicine, and students from the BCM Medical School served as a convenience sample of individuals completing the instrument over a six-month period. Subsequent data analysis consisted of: 1. Conducting an exploratory factor analysis using a Promax rotation to examine the structure of the HPATHI. 2. Estimating the internal consistency reliability of the online version of the HPATHI using Cronbach's alpha coefficient; 3. Determining the concurrent validity of the HPATHI against the ATHI; 4. Comparing extreme groups on their responses to the HPATHI. The extreme groups were determined according to their level of training (preclinical medical students vs. physicians) and according to their experience in working with the homeless (<1 month vs. >1 year). This study was approved by the BCM Institutional Review Board for educational research with human subjects. Data analysis was conducted using SPSS Version 12.0 statistical software for Phases 1 and 2 and SAS ®  (V8.2 and V9.1) for Phase 3.
Stages of development and validation of the HPATHI
In Phase 1, a group of physicians and nurse practitioners, all experts in homeless health care, was recruited through snowball sampling [ 22 ] to serve on a Delphi panel [ 20 ]. These individuals were identified as experts because they work with the homeless on a regular basis and are members of the National Health Care for the Homeless Clinicians' Network. They received a list of statements about the homeless, homelessness, and homeless health care that was compiled by selecting and adapting appropriate items from the AHTI [ 17 ] and the ATHQ [ 18 ]. We, as the authors of this study, added additional items that were based on our experiences and our review of the literature. The experts were asked to classify the statements into one of three categories ("essential," "interesting but not essential," and "irrelevant") and to generate other items that they considered to be necessary to explore health-care professionals' attitudes toward the homeless. The panel reached a consensus on the items to be used in the instrument through successive rankings of the items. The statements were then combined into an instrument with a five-point Likert scale (1 = strongly disagree; 2 = disagree; 3 = neither agree nor disagree; 4 = agree; and 5 = strongly agree) organized around three thematic areas: a)  attitudes  toward the homeless; b)  interest  in working with the homeless; and c)  confidence  in one's ability to work with the homeless.attitudesinterestconfidenceDuring Phase 2, we administered the first draft of the HPATHI to a convenience sample of third-year medical students enrolled at Baylor College of Medicine (BCM) in Houston, Texas. These students were selected because they showed an interest in working with the homeless by registering for an elective course that allows students to provide health care to the homeless in a clinic setting [ 23 ]. Of the 100 students who attended class on the day that the instrument was administered, 72 completed it and were asked to provide contact information for the retest. Student responses to the instrument were analyzed using Cronbach's alpha coefficient to establish its internal consistency. Two weeks later, 34 of the 63 students who provided e-mail addresses completed the instrument a second time, thereby providing the data to determine the HPATHI's test-retest reliability. We then conducted an item analysis of redundant items or those with poor item-to-scale correlations.In Phase 3, we prepared Web-based versions of the HPATHI and of the ATHI and sent the Internet link to our target population with a standard invitation to complete both instruments. Primary care physicians who serve as faculty in the BCM Department of Family and Community Medicine, family practice residents in the BCM Department of Family and Community Medicine, general internal medicine residents in the BCM Department of Family and Community Medicine, and students from the BCM Medical School served as a convenience sample of individuals completing the instrument over a six-month period. Subsequent data analysis consisted of:1. Conducting an exploratory factor analysis using a Promax rotation to examine the structure of the HPATHI.2. Estimating the internal consistency reliability of the online version of the HPATHI using Cronbach's alpha coefficient;3. Determining the concurrent validity of the HPATHI against the ATHI;4. Comparing extreme groups on their responses to the HPATHI. The extreme groups were determined according to their level of training (preclinical medical students vs. physicians) and according to their experience in working with the homeless (<1 month vs. >1 year).This study was approved by the BCM Institutional Review Board for educational research with human subjects. Data analysis was conducted using SPSS Version 12.0 statistical software for Phases 1 and 2 and SAS ®  (V8.2 and V9.1) for Phase 3.Results Phase 1: instrument development Of the 23 panel members who received the first list of 24 statements, 16 (70%) reviewed them, rank ordered them, and generated an additional 26 statements. We rearranged the combined list of 50 statements according to the proposed ranking ("essential," "interesting but not essential," and "irrelevant") and returned them to the 16 panel members for a second ranking. Based on their responses, six statements were eliminated and the remaining 44 were returned to the 16 panel members for a third ranking. Nine panel members returned responses after this iteration, and we eliminated nine additional items according to their recommendations. The remaining 35 items then constituted the first draft of the instrument we named the Healthcare Professionals' Attitude Toward the Homeless Inventory (HPATHI). Although seven panel members did not participate in the third iteration, their rankings in the second iteration corresponded to the final list of items. Phase 2: pilot administration of the 35-item HPATHI The sample population of third-year medical students completed a pilot administration of the 35-item HPATHI; the subset of students who responded two weeks later underwent a second administration of the same instrument. Table  1  displays the means and standard deviations of student responses to both administrations of the HPATHI. Items 2, 5, 6, 11, 15, 16, 20, and 23 were reverse-coded for the analysis so that a higher total mean on the instrument would indicate a positive attitude toward the homeless. Table 1 Means and standard deviations for HPATHI* test and retest Statement Test n = 76 Retest n = 34 M SD M SD 1. Homeless people are victims of circumstance. 3.26 .839 3.24 .819 2. Most homeless people are mentally ill. 2.90 .875 3.24 .955 3. Homeless people have the right to basic health care. 4.60 .620 4.68 .475 4. Homelessness is a major problem in our society. 4.36 .698 4.50 .707 5. Homeless people choose to be homeless. 3.71 .777 3.91 .712 6. Homeless people are lazy. 3.82 .738 3.94 .694 7. Health care dollars should be directed toward serving the poor and homeless. 3.83 .888 4.03 .717 8. Doctors should address the physical and social problems of the homeless. 4.17 .839 4.47 .563 9. Doctors have a duty to care for the homeless. 3.94 .977 4.18 .834 10. Caring for the homeless is pointless since they do not follow-up. 4.14 .612 4.24 .654 11. Providing medical care for the homeless is futile. 4.04 .740 4.21 .592 12. I am comfortable being a primary care provider for a homeless person with a major mental illness. 3.03 1.14 3.44 1.05 13. I feel comfortable being part of a team when providing care to the homeless. 4.32 .535 4.15 .643 14. I feel comfortable providing care to different minority and cultural groups. 4.42 .710 4.18 .673 15. I feel overwhelmed by the complexity of the problems that homeless people have. 2.97 .839 3.09 .996 16. I understand that my patients' priorities may be more important than following my medical recommendations. 3.97 .769 4.24 .741 17. I entered medicine because I want to help those in need. 4.42 .687 4.62 .551 18. I am interested in working with the underserved. 3.96 .941 3.88 .946 19. I enjoy addressing psychosocial issues with patients. 3.69 .973 3.74 1.08 20. I resent the amount of time it takes to see homeless patients. 3.79 .604 3.94 .547 21. I enjoy learning about the lives of my homeless patients. 3.58 .921 3.82 .834 22. I believe social justice is an important part of health care. 3.75 1.06 3.74 1.14 23. I believe caring for the homeless is not financially viable for my career. 3.24 .831 3.26 .864 24. I am too pressed for time to investigate psychosocial issues routinely. 3.37 .941 3.56 .894 25. I feel overwhelmed by the number of problems that homeless people have. 2.79 .844 2.88 .844 26. My knowledge regarding the problem of homelessness is adequate. 2.58 .931 2.65 .884 27. I can provide care for the homeless effectively. 2.97 .878 3.00 .921 28. Homeless people come from all walks of life. 4.42 .622 4.65 .485 29. Most homeless people tend to be drug addicts or alcoholics. 3.10 .735 3.38 .697 30. I think mentally ill homeless people refuse to get treatment. 3.67 .692 3.82 .797 31. Homeless people are dangerous, aggressive, and physically threatening. 3.97 .556 3.97 .627 32. There are only a few children among the homeless population. 4.31 .493 4.32 .684 33. All people have a right to basic health care. 4.50 .805 4.59 .657 34. I feel it is important to provide care to all socio-economic groups. 4.54 .670 4.62 .604 35. Most poor people have adequate access to health care through the public system. 2.15 1.02 2.03 .937 Totals 114 6.93 116 7.75 * Statements 24–35 were excluded from HPATHI after analysis. Cronbach's alpha coefficient for the first administration was 0.87; the test-retest reliability coefficient (Pearson r) was 0.69. Through an item analysis we discarded 12 items that were either highly correlated with other items, and were thus considered repetitious, or that had item-scale correlations less than 0.20. Phase 3: administration of the HPATHI to the target population One hundred and sixty health-care professionals (24 primary care physicians, 15 primary care residents, 47 clinical medical students, 71 preclinical medical students, and 3 medical students who did not specify their education level) from one academic institution completed the HPATHI; 147 of them also completed the ATHI. Table  2  displays the means and standard deviations for both instruments by gender, by level of training (primary care physician; primary care resident; clinical medical student; preclinical medical student), and by experience with the homeless (no experience; <1 month, >1 month but <1 year, and >1 year). Table 2 Comparison of the HPATHI and ATHI by gender, level of training, and experience HPATHI ATHI N Mean SD N Mean SD Total 160 3.90 0.34 147 3.36 0.28 Gender  Female 103 3.95 0.30 96 3.38 0.26  Male 57 3.81 0.38 51 3.32 0.30 Level of Training†  MS1 55 3.89 0.32 54 3.34 0.26  MS2 16 4.10 0.23 16 3.47 0.21  MS3 28 3.91 0.41 26 3.38 0.36  MS4 19 3.84 0.30 18 3.33 0.25  Resident 15 3.73 0.22 13 3.30 0.25  Faculty 24 3.93 0.36 18 3.38 0.30 Experience  None 31 3.72 0.33 28 3.21 0.23  <1 month 64 3.91 0.30 62 3.37 0.27  >1 month & <1 year 30 3.88 0.32 25 3.37 0.22  1 – 3 years 17 4.10 0.28 16 3.49 0.31  >3 years 18 4.05 0.38 16 3.46 0.33 † On the HPATHI, 3 respondents failed to indicate a level of training and on the ATHI, 2 respondents failed to indicate a level of training. The exploratory factor analysis (principal components), using a Promax rotation to account for the relationship among the factors, yielded a three-factor structure that explained 39% of the variance of the data. Factor 1 consisted of items 12, 13, 14, 17, 18, 19, 20, 21, 22, and 23 and was labeled Personal Advocacy; factor 2 consisted of items 1, 3, 4, 7, 8, 9, and 15 and was labeled Social Advocacy; and factor 3 consisted of items 5, 6, 10, and 11 and was labeled Cynicism. Table  3  presents the items with their loadings in each factor. Table 3 Factor loadings for the 23-item HPATHI Factor 1 Factor 2 Factor 3 1. Homeless people are victims of circumstance. -0.095 0.518 0.064 3. Homeless people have the right to basic health care. -0.096 0.644 0.154 4. Homelessness is a major problem in our society. -0.124 0.677 0.140 5. Homeless people choose to be homeless. 0.008 0.233 0.469 6. Homeless people are lazy. -0.026 0.330 0.559 7. Health-care dollars should be directed toward serving the poor and homeless. 0.180 0.575 0.079 8. I am comfortable being a primary care provider for a homeless person with a major mental illness. 0.329 0.466 -0.071 9. I feel comfortable being part of a team when providing care to the homeless. -0.015 0.514 0.188 10. I feel comfortable providing care to different minority and cultural groups. -0.007 0.152 0.725 11. I feel overwhelmed by the complexity of the problems that homeless people have. 0.028 0.056 0.748 12. I understand that my patients' priorities may be more important than following my medical recommendations. 0.469 -0.206 0.202 13. Doctors should address the physical and social problems of the homeless. 0.438 -0.046 0.395 17. I entered medicine because I want to help those in need. 0.485 0.003 0.088 18. I am interested in working with the underserved. 0.516 0.168 0.085 19. I enjoy addressing psychosocial issues with patients. 0.697 0.106 -0.224 20. I resent the amount of time it takes to see homeless patients. 0.613 -0.214 0.097 21. I enjoy learning about the lives of my homeless patients. 0.788 -0.039 -0.188 22. I believe social justice is an important part of health care. 0.509 0.404 -0.154 23. I believe caring for the homeless is not financially viable for my career. 0.504 -0.096 0.042 The HPATHI was further shortened to 19 items by the deletion of four more items, which either were not represented in the three-factor structure (items 2, 14, and 16) or had an adverse effect on the subscale's reliability (item 15). The three subscales were also significantly related to each other: factor 1 had Pearson's r correlations of 0.47 (n = 160; p < 0.001) with factor 2 and 0.43 (n = 160; p < 0.001) with factor 3; and factor 2 had a Pearson's r correlation of 0.48 (n = 160; p < 0.001) with factor 3. Table  4  displays the descriptive statistics and measurement properties for the 19-item HPATHI total and subscales. These three factors, if taken as subscales for the HPATHI, showed satisfactory Cronbach's alpha coefficients: 0.75, 0.72, 0.72, and 0.84 respectively for factor 1 (mean = 3.86; sd = 0.47), factor 2 (mean = 4.06; sd = 0.46), factor 3 (mean = 4.06; sd = 0.50), and total scale (mean = 3.96; sd = 0.38). Table 4 Measurement properties for reduced HPATHI scale and subscales Descriptive Statistics Subscale Statistics Full-scale Statistics Item Mean SD Scale ¶ Item-Total Correlation Cronbach's Alpha if Deleted Item-Total Correlation Cronbach's Alpha if Deleted 1 2.55 0.76 SA 0.28 0.73 0.27 0.84 3 1.45 0.61 SA 0.52 0.66 0.40 0.83 4 1.68 0.71 SA 0.48 0.67 0.39 0.83 5 2.20 0.80 C 0.42 0.73 0.40 0.83 6 2.14 0.65 C 0.53 0.65 0.50 0.83 7 2.15 0.79 SA 0.48 0.67 0.55 0.82 8 1.81 0.67 SA 0.49 0.67 0.50 0.82 9 2.01 0.72 SA 0.47 0.67 0.39 0.83 10 1.76 0.60 C 0.59 0.62 0.47 0.83 11 1.68 0.64 C 0.54 0.65 0.44 0.83 12 2.82 0.96 PA 0.31 0.75 0.31 0.84 13 1.79 0.58 PA 0.43 0.73 0.47 0.83 17 1.63 0.58 PA 0.38 0.73 0.37 0.83 18 1.84 0.78 PA 0.51 0.71 0.52 0.82 19 2.23 0.97 PA 0.51 0.71 0.47 0.83 20 2.09 0.74 PA 0.40 0.73 0.36 0.83 21 2.19 0.78 PA 0.55 0.71 0.46 0.83 22 2.00 0.85 PA 0.49 0.71 0.54 0.82 23 2.66 0.94 PA 0.34 0.74 0.31 0.84 ¶ PA = Personal Advocacy; SA = Social Advocacy; C = Cynicism The Pearson's correlation coefficient between the HPATHI and the ATHI was 0.68 for the HPATHI's total scale (concurrent validity) (Table  4 ). For the extreme group comparisons, no significant difference was found between preclinical medical students and primary care physicians in their responses to the HPATHI (F = 1.05; df = 3, 156; p = 0.371). On the other hand, respondents who had more than one year of experience with the homeless scored significantly higher than those who had less than one month of experience (F = 6.19; df = 2, 157; p = 0.003) (Table  5 ). When the individual hypothetical subscales were considered, all items were either moderately or strongly correlated with their respective subscales (range of Pearson's correlation coefficients, 0.38 to 0.68). However, when the entire instrument was considered, the item analysis showed that items 1, 2, 15, and 16 had low item-scale correlations (Pearson's r < 0.24). Table 5 Extreme group comparisons by level of training and experience with the homeless N Mean SD Level of Training  MS1 & MS2 71 3.94 0.31  Residents & Faculty 39 3.85 0.33 Experience with the Homeless‡  Less than 1 month 95 3.85 0.32  More than 1 year 35 4.01 0.33 ‡ Differences between the means of the two groups by experience were statistically significant (p < 0.01)
Results
Phase 1: instrument development Of the 23 panel members who received the first list of 24 statements, 16 (70%) reviewed them, rank ordered them, and generated an additional 26 statements. We rearranged the combined list of 50 statements according to the proposed ranking ("essential," "interesting but not essential," and "irrelevant") and returned them to the 16 panel members for a second ranking. Based on their responses, six statements were eliminated and the remaining 44 were returned to the 16 panel members for a third ranking. Nine panel members returned responses after this iteration, and we eliminated nine additional items according to their recommendations. The remaining 35 items then constituted the first draft of the instrument we named the Healthcare Professionals' Attitude Toward the Homeless Inventory (HPATHI). Although seven panel members did not participate in the third iteration, their rankings in the second iteration corresponded to the final list of items.
Phase 1: instrument development
Of the 23 panel members who received the first list of 24 statements, 16 (70%) reviewed them, rank ordered them, and generated an additional 26 statements. We rearranged the combined list of 50 statements according to the proposed ranking ("essential," "interesting but not essential," and "irrelevant") and returned them to the 16 panel members for a second ranking. Based on their responses, six statements were eliminated and the remaining 44 were returned to the 16 panel members for a third ranking. Nine panel members returned responses after this iteration, and we eliminated nine additional items according to their recommendations. The remaining 35 items then constituted the first draft of the instrument we named the Healthcare Professionals' Attitude Toward the Homeless Inventory (HPATHI). Although seven panel members did not participate in the third iteration, their rankings in the second iteration corresponded to the final list of items.Phase 2: pilot administration of the 35-item HPATHI The sample population of third-year medical students completed a pilot administration of the 35-item HPATHI; the subset of students who responded two weeks later underwent a second administration of the same instrument. Table  1  displays the means and standard deviations of student responses to both administrations of the HPATHI. Items 2, 5, 6, 11, 15, 16, 20, and 23 were reverse-coded for the analysis so that a higher total mean on the instrument would indicate a positive attitude toward the homeless. Table 1 Means and standard deviations for HPATHI* test and retest Statement Test n = 76 Retest n = 34 M SD M SD 1. Homeless people are victims of circumstance. 3.26 .839 3.24 .819 2. Most homeless people are mentally ill. 2.90 .875 3.24 .955 3. Homeless people have the right to basic health care. 4.60 .620 4.68 .475 4. Homelessness is a major problem in our society. 4.36 .698 4.50 .707 5. Homeless people choose to be homeless. 3.71 .777 3.91 .712 6. Homeless people are lazy. 3.82 .738 3.94 .694 7. Health care dollars should be directed toward serving the poor and homeless. 3.83 .888 4.03 .717 8. Doctors should address the physical and social problems of the homeless. 4.17 .839 4.47 .563 9. Doctors have a duty to care for the homeless. 3.94 .977 4.18 .834 10. Caring for the homeless is pointless since they do not follow-up. 4.14 .612 4.24 .654 11. Providing medical care for the homeless is futile. 4.04 .740 4.21 .592 12. I am comfortable being a primary care provider for a homeless person with a major mental illness. 3.03 1.14 3.44 1.05 13. I feel comfortable being part of a team when providing care to the homeless. 4.32 .535 4.15 .643 14. I feel comfortable providing care to different minority and cultural groups. 4.42 .710 4.18 .673 15. I feel overwhelmed by the complexity of the problems that homeless people have. 2.97 .839 3.09 .996 16. I understand that my patients' priorities may be more important than following my medical recommendations. 3.97 .769 4.24 .741 17. I entered medicine because I want to help those in need. 4.42 .687 4.62 .551 18. I am interested in working with the underserved. 3.96 .941 3.88 .946 19. I enjoy addressing psychosocial issues with patients. 3.69 .973 3.74 1.08 20. I resent the amount of time it takes to see homeless patients. 3.79 .604 3.94 .547 21. I enjoy learning about the lives of my homeless patients. 3.58 .921 3.82 .834 22. I believe social justice is an important part of health care. 3.75 1.06 3.74 1.14 23. I believe caring for the homeless is not financially viable for my career. 3.24 .831 3.26 .864 24. I am too pressed for time to investigate psychosocial issues routinely. 3.37 .941 3.56 .894 25. I feel overwhelmed by the number of problems that homeless people have. 2.79 .844 2.88 .844 26. My knowledge regarding the problem of homelessness is adequate. 2.58 .931 2.65 .884 27. I can provide care for the homeless effectively. 2.97 .878 3.00 .921 28. Homeless people come from all walks of life. 4.42 .622 4.65 .485 29. Most homeless people tend to be drug addicts or alcoholics. 3.10 .735 3.38 .697 30. I think mentally ill homeless people refuse to get treatment. 3.67 .692 3.82 .797 31. Homeless people are dangerous, aggressive, and physically threatening. 3.97 .556 3.97 .627 32. There are only a few children among the homeless population. 4.31 .493 4.32 .684 33. All people have a right to basic health care. 4.50 .805 4.59 .657 34. I feel it is important to provide care to all socio-economic groups. 4.54 .670 4.62 .604 35. Most poor people have adequate access to health care through the public system. 2.15 1.02 2.03 .937 Totals 114 6.93 116 7.75 * Statements 24–35 were excluded from HPATHI after analysis. Cronbach's alpha coefficient for the first administration was 0.87; the test-retest reliability coefficient (Pearson r) was 0.69. Through an item analysis we discarded 12 items that were either highly correlated with other items, and were thus considered repetitious, or that had item-scale correlations less than 0.20.
Phase 2: pilot administration of the 35-item HPATHI
The sample population of third-year medical students completed a pilot administration of the 35-item HPATHI; the subset of students who responded two weeks later underwent a second administration of the same instrument. Table  1  displays the means and standard deviations of student responses to both administrations of the HPATHI. Items 2, 5, 6, 11, 15, 16, 20, and 23 were reverse-coded for the analysis so that a higher total mean on the instrument would indicate a positive attitude toward the homeless.Means and standard deviations for HPATHI* test and retestStatementStatementTest n = 76Test n = 76Retest n = 34Retest n = 34MMSDSDMMSDSDTotalsTotals* Statements 24–35 were excluded from HPATHI after analysis.Cronbach's alpha coefficient for the first administration was 0.87; the test-retest reliability coefficient (Pearson r) was 0.69. Through an item analysis we discarded 12 items that were either highly correlated with other items, and were thus considered repetitious, or that had item-scale correlations less than 0.20.Phase 3: administration of the HPATHI to the target population One hundred and sixty health-care professionals (24 primary care physicians, 15 primary care residents, 47 clinical medical students, 71 preclinical medical students, and 3 medical students who did not specify their education level) from one academic institution completed the HPATHI; 147 of them also completed the ATHI. Table  2  displays the means and standard deviations for both instruments by gender, by level of training (primary care physician; primary care resident; clinical medical student; preclinical medical student), and by experience with the homeless (no experience; <1 month, >1 month but <1 year, and >1 year). Table 2 Comparison of the HPATHI and ATHI by gender, level of training, and experience HPATHI ATHI N Mean SD N Mean SD Total 160 3.90 0.34 147 3.36 0.28 Gender  Female 103 3.95 0.30 96 3.38 0.26  Male 57 3.81 0.38 51 3.32 0.30 Level of Training†  MS1 55 3.89 0.32 54 3.34 0.26  MS2 16 4.10 0.23 16 3.47 0.21  MS3 28 3.91 0.41 26 3.38 0.36  MS4 19 3.84 0.30 18 3.33 0.25  Resident 15 3.73 0.22 13 3.30 0.25  Faculty 24 3.93 0.36 18 3.38 0.30 Experience  None 31 3.72 0.33 28 3.21 0.23  <1 month 64 3.91 0.30 62 3.37 0.27  >1 month & <1 year 30 3.88 0.32 25 3.37 0.22  1 – 3 years 17 4.10 0.28 16 3.49 0.31  >3 years 18 4.05 0.38 16 3.46 0.33 † On the HPATHI, 3 respondents failed to indicate a level of training and on the ATHI, 2 respondents failed to indicate a level of training. The exploratory factor analysis (principal components), using a Promax rotation to account for the relationship among the factors, yielded a three-factor structure that explained 39% of the variance of the data. Factor 1 consisted of items 12, 13, 14, 17, 18, 19, 20, 21, 22, and 23 and was labeled Personal Advocacy; factor 2 consisted of items 1, 3, 4, 7, 8, 9, and 15 and was labeled Social Advocacy; and factor 3 consisted of items 5, 6, 10, and 11 and was labeled Cynicism. Table  3  presents the items with their loadings in each factor. Table 3 Factor loadings for the 23-item HPATHI Factor 1 Factor 2 Factor 3 1. Homeless people are victims of circumstance. -0.095 0.518 0.064 3. Homeless people have the right to basic health care. -0.096 0.644 0.154 4. Homelessness is a major problem in our society. -0.124 0.677 0.140 5. Homeless people choose to be homeless. 0.008 0.233 0.469 6. Homeless people are lazy. -0.026 0.330 0.559 7. Health-care dollars should be directed toward serving the poor and homeless. 0.180 0.575 0.079 8. I am comfortable being a primary care provider for a homeless person with a major mental illness. 0.329 0.466 -0.071 9. I feel comfortable being part of a team when providing care to the homeless. -0.015 0.514 0.188 10. I feel comfortable providing care to different minority and cultural groups. -0.007 0.152 0.725 11. I feel overwhelmed by the complexity of the problems that homeless people have. 0.028 0.056 0.748 12. I understand that my patients' priorities may be more important than following my medical recommendations. 0.469 -0.206 0.202 13. Doctors should address the physical and social problems of the homeless. 0.438 -0.046 0.395 17. I entered medicine because I want to help those in need. 0.485 0.003 0.088 18. I am interested in working with the underserved. 0.516 0.168 0.085 19. I enjoy addressing psychosocial issues with patients. 0.697 0.106 -0.224 20. I resent the amount of time it takes to see homeless patients. 0.613 -0.214 0.097 21. I enjoy learning about the lives of my homeless patients. 0.788 -0.039 -0.188 22. I believe social justice is an important part of health care. 0.509 0.404 -0.154 23. I believe caring for the homeless is not financially viable for my career. 0.504 -0.096 0.042 The HPATHI was further shortened to 19 items by the deletion of four more items, which either were not represented in the three-factor structure (items 2, 14, and 16) or had an adverse effect on the subscale's reliability (item 15). The three subscales were also significantly related to each other: factor 1 had Pearson's r correlations of 0.47 (n = 160; p < 0.001) with factor 2 and 0.43 (n = 160; p < 0.001) with factor 3; and factor 2 had a Pearson's r correlation of 0.48 (n = 160; p < 0.001) with factor 3. Table  4  displays the descriptive statistics and measurement properties for the 19-item HPATHI total and subscales. These three factors, if taken as subscales for the HPATHI, showed satisfactory Cronbach's alpha coefficients: 0.75, 0.72, 0.72, and 0.84 respectively for factor 1 (mean = 3.86; sd = 0.47), factor 2 (mean = 4.06; sd = 0.46), factor 3 (mean = 4.06; sd = 0.50), and total scale (mean = 3.96; sd = 0.38). Table 4 Measurement properties for reduced HPATHI scale and subscales Descriptive Statistics Subscale Statistics Full-scale Statistics Item Mean SD Scale ¶ Item-Total Correlation Cronbach's Alpha if Deleted Item-Total Correlation Cronbach's Alpha if Deleted 1 2.55 0.76 SA 0.28 0.73 0.27 0.84 3 1.45 0.61 SA 0.52 0.66 0.40 0.83 4 1.68 0.71 SA 0.48 0.67 0.39 0.83 5 2.20 0.80 C 0.42 0.73 0.40 0.83 6 2.14 0.65 C 0.53 0.65 0.50 0.83 7 2.15 0.79 SA 0.48 0.67 0.55 0.82 8 1.81 0.67 SA 0.49 0.67 0.50 0.82 9 2.01 0.72 SA 0.47 0.67 0.39 0.83 10 1.76 0.60 C 0.59 0.62 0.47 0.83 11 1.68 0.64 C 0.54 0.65 0.44 0.83 12 2.82 0.96 PA 0.31 0.75 0.31 0.84 13 1.79 0.58 PA 0.43 0.73 0.47 0.83 17 1.63 0.58 PA 0.38 0.73 0.37 0.83 18 1.84 0.78 PA 0.51 0.71 0.52 0.82 19 2.23 0.97 PA 0.51 0.71 0.47 0.83 20 2.09 0.74 PA 0.40 0.73 0.36 0.83 21 2.19 0.78 PA 0.55 0.71 0.46 0.83 22 2.00 0.85 PA 0.49 0.71 0.54 0.82 23 2.66 0.94 PA 0.34 0.74 0.31 0.84 ¶ PA = Personal Advocacy; SA = Social Advocacy; C = Cynicism The Pearson's correlation coefficient between the HPATHI and the ATHI was 0.68 for the HPATHI's total scale (concurrent validity) (Table  4 ). For the extreme group comparisons, no significant difference was found between preclinical medical students and primary care physicians in their responses to the HPATHI (F = 1.05; df = 3, 156; p = 0.371). On the other hand, respondents who had more than one year of experience with the homeless scored significantly higher than those who had less than one month of experience (F = 6.19; df = 2, 157; p = 0.003) (Table  5 ). When the individual hypothetical subscales were considered, all items were either moderately or strongly correlated with their respective subscales (range of Pearson's correlation coefficients, 0.38 to 0.68). However, when the entire instrument was considered, the item analysis showed that items 1, 2, 15, and 16 had low item-scale correlations (Pearson's r < 0.24). Table 5 Extreme group comparisons by level of training and experience with the homeless N Mean SD Level of Training  MS1 & MS2 71 3.94 0.31  Residents & Faculty 39 3.85 0.33 Experience with the Homeless‡  Less than 1 month 95 3.85 0.32  More than 1 year 35 4.01 0.33 ‡ Differences between the means of the two groups by experience were statistically significant (p < 0.01)
Phase 3: administration of the HPATHI to the target population
One hundred and sixty health-care professionals (24 primary care physicians, 15 primary care residents, 47 clinical medical students, 71 preclinical medical students, and 3 medical students who did not specify their education level) from one academic institution completed the HPATHI; 147 of them also completed the ATHI. Table  2  displays the means and standard deviations for both instruments by gender, by level of training (primary care physician; primary care resident; clinical medical student; preclinical medical student), and by experience with the homeless (no experience; <1 month, >1 month but <1 year, and >1 year).Comparison of the HPATHI and ATHI by gender, level of training, and experienceTotalGenderLevel of Training†Experience† On the HPATHI, 3 respondents failed to indicate a level of training and on the ATHI, 2 respondents failed to indicate a level of training.The exploratory factor analysis (principal components), using a Promax rotation to account for the relationship among the factors, yielded a three-factor structure that explained 39% of the variance of the data. Factor 1 consisted of items 12, 13, 14, 17, 18, 19, 20, 21, 22, and 23 and was labeled Personal Advocacy; factor 2 consisted of items 1, 3, 4, 7, 8, 9, and 15 and was labeled Social Advocacy; and factor 3 consisted of items 5, 6, 10, and 11 and was labeled Cynicism. Table  3  presents the items with their loadings in each factor.Factor loadings for the 23-item HPATHIFactor 1Factor 2Factor 3The HPATHI was further shortened to 19 items by the deletion of four more items, which either were not represented in the three-factor structure (items 2, 14, and 16) or had an adverse effect on the subscale's reliability (item 15). The three subscales were also significantly related to each other: factor 1 had Pearson's r correlations of 0.47 (n = 160; p < 0.001) with factor 2 and 0.43 (n = 160; p < 0.001) with factor 3; and factor 2 had a Pearson's r correlation of 0.48 (n = 160; p < 0.001) with factor 3. Table  4  displays the descriptive statistics and measurement properties for the 19-item HPATHI total and subscales. These three factors, if taken as subscales for the HPATHI, showed satisfactory Cronbach's alpha coefficients: 0.75, 0.72, 0.72, and 0.84 respectively for factor 1 (mean = 3.86; sd = 0.47), factor 2 (mean = 4.06; sd = 0.46), factor 3 (mean = 4.06; sd = 0.50), and total scale (mean = 3.96; sd = 0.38).Measurement properties for reduced HPATHI scale and subscales¶ PA = Personal Advocacy; SA = Social Advocacy; C = CynicismThe Pearson's correlation coefficient between the HPATHI and the ATHI was 0.68 for the HPATHI's total scale (concurrent validity) (Table  4 ). For the extreme group comparisons, no significant difference was found between preclinical medical students and primary care physicians in their responses to the HPATHI (F = 1.05; df = 3, 156; p = 0.371). On the other hand, respondents who had more than one year of experience with the homeless scored significantly higher than those who had less than one month of experience (F = 6.19; df = 2, 157; p = 0.003) (Table  5 ). When the individual hypothetical subscales were considered, all items were either moderately or strongly correlated with their respective subscales (range of Pearson's correlation coefficients, 0.38 to 0.68). However, when the entire instrument was considered, the item analysis showed that items 1, 2, 15, and 16 had low item-scale correlations (Pearson's r < 0.24).Extreme group comparisons by level of training and experience with the homelessNMeanSDLevel of TrainingExperience with the Homeless‡‡ Differences between the means of the two groups by experience were statistically significant (p < 0.01)Discussion Using the Delphi method to select the survey items helped ensure the HPATHI's content validity. Not only were the items selected and validated by homeless health-care experts, but the items chosen for inclusion in the HPATHI were based on findings from current literature on the issue. In addition, by correlating the HPATHI with the ATHI, we were able to demonstrate satisfactory concurrent validity. Construct validity for the HPATHI (i.e., attitudes toward the homeless) was determined by the extreme group comparisons, the item analyses, and the factor analysis. Results of the extreme group comparisons showed that experience with the homeless, rather than medical training, is a significant factor that correlates with health-care professionals' attitudes towards the homeless and their interest in working with the homeless population. Moreover, individuals who had more extensive experience with the homeless showed more positive attitudes toward and interest in homeless patients. Therefore, increasing the opportunities to provide direct patient care to the homeless might improve the attitudes of health-care professionals toward this group. The factor analysis suggested that we do have potential subscales in the instrument that may offer meaningful information regarding the general attitudes of health-care professionals who work with the homeless. The three subscales appear to represent:  personal advocacy , which contains the items that reflect a personal commitment to work with the homeless;  social advocacy , which consists of the items that reflect society's responsibility to care for the homeless population; and  cynicism , which encompasses the items that reflect a negative attitude and a sense of futility in working with the homeless. A limitation of this study is that only 160 health-care professionals participated in the online administration of the HPATHI. This small sample size limits the effectiveness of the factor analysis. Moreover, our sample focused only on the medical profession as represented by medical students and primary care residents and physicians. The participation of a larger number of health-care professionals from other medical specialties would strengthen the study.
Discussion
Using the Delphi method to select the survey items helped ensure the HPATHI's content validity. Not only were the items selected and validated by homeless health-care experts, but the items chosen for inclusion in the HPATHI were based on findings from current literature on the issue. In addition, by correlating the HPATHI with the ATHI, we were able to demonstrate satisfactory concurrent validity. Construct validity for the HPATHI (i.e., attitudes toward the homeless) was determined by the extreme group comparisons, the item analyses, and the factor analysis.Results of the extreme group comparisons showed that experience with the homeless, rather than medical training, is a significant factor that correlates with health-care professionals' attitudes towards the homeless and their interest in working with the homeless population. Moreover, individuals who had more extensive experience with the homeless showed more positive attitudes toward and interest in homeless patients. Therefore, increasing the opportunities to provide direct patient care to the homeless might improve the attitudes of health-care professionals toward this group.The factor analysis suggested that we do have potential subscales in the instrument that may offer meaningful information regarding the general attitudes of health-care professionals who work with the homeless. The three subscales appear to represent:  personal advocacy , which contains the items that reflect a personal commitment to work with the homeless;  social advocacy , which consists of the items that reflect society's responsibility to care for the homeless population; and  cynicism , which encompasses the items that reflect a negative attitude and a sense of futility in working with the homeless.personal advocacysocial advocacycynicismA limitation of this study is that only 160 health-care professionals participated in the online administration of the HPATHI. This small sample size limits the effectiveness of the factor analysis. Moreover, our sample focused only on the medical profession as represented by medical students and primary care residents and physicians. The participation of a larger number of health-care professionals from other medical specialties would strengthen the study.Conclusions The development of the HPATHI has many implications for and applications to future research on homeless health care, although its most valuable use may be to assess the attitudes toward homeless persons of medical students, residents, and practicing physicians. Throughout its various iterations, the instrument demonstrated strong internal consistency reliability for the total scale and satisfactory test-retest reliability. The scales identified by the factor analysis also showed satisfactory internal consistency reliability. The information collected from the expert panel and the literature search on attitudes toward the homeless and their health-care status proved to be an excellent framework for determining which statements to retain for the final instrument. The inter-item correlations and the correlations among the subscales indicate that the items are measuring similar underlying constructs within an overall theme – the attitudes of health-care professionals toward the homeless. Despite the limited sampling, the research process has demonstrated that the HPATHI is a reliable and valid instrument that has the ability to assess the attitudes of health-care professionals toward the homeless population. We believe that the instrument may also be used in the future within the academic framework of medical schools to determine if attitudinal changes are affected by training experiences occurring with the homeless. To determine whether this is the case, we intend to administer the HPATHI as a pre/post-test survey to students who enroll in the homeless health-care track. Moreover, over the next year, we plan to keep on assessing the attitudes of health-care professionals toward the homeless by having new groups respond simultaneously to the ATHI and the HPATHI, as was done in Phase 3 of the original study. Additionally, we intend to include participants from other medical schools in the United States and to expand our sample to other health-care professionals who traditionally work with the homeless, to further test the instrument's overall validity.
Conclusions
The development of the HPATHI has many implications for and applications to future research on homeless health care, although its most valuable use may be to assess the attitudes toward homeless persons of medical students, residents, and practicing physicians. Throughout its various iterations, the instrument demonstrated strong internal consistency reliability for the total scale and satisfactory test-retest reliability. The scales identified by the factor analysis also showed satisfactory internal consistency reliability. The information collected from the expert panel and the literature search on attitudes toward the homeless and their health-care status proved to be an excellent framework for determining which statements to retain for the final instrument. The inter-item correlations and the correlations among the subscales indicate that the items are measuring similar underlying constructs within an overall theme – the attitudes of health-care professionals toward the homeless.Despite the limited sampling, the research process has demonstrated that the HPATHI is a reliable and valid instrument that has the ability to assess the attitudes of health-care professionals toward the homeless population. We believe that the instrument may also be used in the future within the academic framework of medical schools to determine if attitudinal changes are affected by training experiences occurring with the homeless. To determine whether this is the case, we intend to administer the HPATHI as a pre/post-test survey to students who enroll in the homeless health-care track. Moreover, over the next year, we plan to keep on assessing the attitudes of health-care professionals toward the homeless by having new groups respond simultaneously to the ATHI and the HPATHI, as was done in Phase 3 of the original study. Additionally, we intend to include participants from other medical schools in the United States and to expand our sample to other health-care professionals who traditionally work with the homeless, to further test the instrument's overall validity.Competing interests The author(s) declare that they have no competing interests.
Competing interests
The author(s) declare that they have no competing interests.Authors' contributions DB contributed to the conception, design, and acquisition of data, and drafted and revised the article. FMM contributed to the conception, design, and acquisition of data, helped draft the article, and carried out the data analysis. SK contributed to the conception, design, and acquisition of data, helped draft the article, and carried out the data analysis. DR contributed to the draft of the manuscript and critically revised it for important content. DLC contributed to the conception, design, and acquisition of data. AM contributed to the conception, design, and acquisition of data. RJV contributed to the interpretation of the data and critically revised it for important content. All authors read and approved the final manuscript
Authors' contributions
DB contributed to the conception, design, and acquisition of data, and drafted and revised the article. FMM contributed to the conception, design, and acquisition of data, helped draft the article, and carried out the data analysis. SK contributed to the conception, design, and acquisition of data, helped draft the article, and carried out the data analysis. DR contributed to the draft of the manuscript and critically revised it for important content. DLC contributed to the conception, design, and acquisition of data. AM contributed to the conception, design, and acquisition of data. RJV contributed to the interpretation of the data and critically revised it for important content. All authors read and approved the final manuscriptPre-publication history The pre-publication history for this paper can be accessed here:
Pre-publication history
The pre-publication history for this paper can be accessed here:


Background Gastrointestinal symptoms are common in patients with Chronic Fatigue Syndrome (CFS). The objective of this study was to determine the frequency of these symptoms and explore their relationship with objective (radionuclide) studies of upper GI function.
Background
Gastrointestinal symptoms are common in patients with Chronic Fatigue Syndrome (CFS). The objective of this study was to determine the frequency of these symptoms and explore their relationship with objective (radionuclide) studies of upper GI function.Methods Thirty-two (32) patients with CFS and 45 control subjects completed a questionnaire on upper GI symptoms, and the 32 patients underwent oesophageal clearance, and simultaneous liquid and solid gastric emptying studies using radionuclide techniques compared with historical controls.
Methods
Thirty-two (32) patients with CFS and 45 control subjects completed a questionnaire on upper GI symptoms, and the 32 patients underwent oesophageal clearance, and simultaneous liquid and solid gastric emptying studies using radionuclide techniques compared with historical controls.Results The questionnaires showed a significant difference in gastric (p > 0.01) symptoms and swallowing difficulty. Nocturnal diarrhoea was a significant symptom not previously reported. 5/32 CFS subjects showed slightly delayed oesophageal clearance, but overall there was no significant difference from the control subjects, nor correlation of oesophageal clearance with symptoms. 23/32 patients showed a delay in liquid gastric emptying, and 12/32 a delay in solid gastric emptying with the delay significantly correlated with the mean symptom score (for each p ≪ 0.001).
Results
The questionnaires showed a significant difference in gastric (p > 0.01) symptoms and swallowing difficulty. Nocturnal diarrhoea was a significant symptom not previously reported.5/32 CFS subjects showed slightly delayed oesophageal clearance, but overall there was no significant difference from the control subjects, nor correlation of oesophageal clearance with symptoms. 23/32 patients showed a delay in liquid gastric emptying, and 12/32 a delay in solid gastric emptying with the delay significantly correlated with the mean symptom score (for each p ≪ 0.001).Conclusions GI symptoms in patients with chronic fatigue syndrome are associated with objective changes of upper GI motility.
Conclusions
GI symptoms in patients with chronic fatigue syndrome are associated with objective changes of upper GI motility.

Background Chronic Fatigue Syndrome (CFS) is a descriptive term used to define a classifiable pattern of symptoms that cannot be attributed to any alternative condition [ 1 ]. It can be associated with immunological alterations, neuro-endocrine changes [ 2 ], sleep disturbance and disturbed neurocognitive performance with abnormal cerebral perfusion [ 3 ], but the pathophysiological significance of these is uncertain. Skeletal neuromuscular function is usually normal in CFS sufferers [ 4 ]. Many with CFS have gastro-intestinal (GI) symptoms, which are often unrecognised as being part of CFS. The commonest of the upper GI symptoms include fullness and bloating after a small meal, abdominal distension, nausea, and loss of appetite. Lower GI tract symptoms have considerable overlap with irritable bowel syndrome [ 5 ]. The hypothesis explored in this paper is that symptoms of possible upper gastrointestinal origin are more common in patients with CFS and are related to upper gastrointestinal motility as assessed by radionuclide methods.
Background
Chronic Fatigue Syndrome (CFS) is a descriptive term used to define a classifiable pattern of symptoms that cannot be attributed to any alternative condition [ 1 ]. It can be associated with immunological alterations, neuro-endocrine changes [ 2 ], sleep disturbance and disturbed neurocognitive performance with abnormal cerebral perfusion [ 3 ], but the pathophysiological significance of these is uncertain. Skeletal neuromuscular function is usually normal in CFS sufferers [ 4 ].Many with CFS have gastro-intestinal (GI) symptoms, which are often unrecognised as being part of CFS. The commonest of the upper GI symptoms include fullness and bloating after a small meal, abdominal distension, nausea, and loss of appetite. Lower GI tract symptoms have considerable overlap with irritable bowel syndrome [ 5 ].The hypothesis explored in this paper is that symptoms of possible upper gastrointestinal origin are more common in patients with CFS and are related to upper gastrointestinal motility as assessed by radionuclide methods.Methods Subjects Consecutive patients with CFS who met the Fukuda criteria [ 6 ] for CFS were all seen by a single physician (RB). Patients with any medical condition which could account for chronic fatigue, a BMI > 30, previous GI surgery or medication affecting the rate of gastric emptying were excluded. Overt psychiatric disease was excluded at the interview. The patients were asked to self assess their percentage reduction in activity from prior to the onset of CFS as a marker of severity. Gastro-Intestinal symptoms were evaluated in patients and controls by a standard questionnaire prior to the gastric emptying studies [ 7 ]. Symptoms were divided into " oesophageal " (dysphagia, heart burn, acid regurgitation), " gastric ": (anorexia, nausea, early satiety, bloating, abdominal distension, intermittent abdominal pain), " other " frequency of bowel actions, consistency of stools, presence or absence of diarrhoea, urgency and timing. Symptoms were scored. 0, none, 1, mild (symptom could be ignored), 2, moderate (symptom could not be ignored, but did not influence daily activities), 3, severe, (symptom influenced daily activities). A mean symptom score (maximum score 3) for the 6 gastric symptoms, and 3 oesophageal symptoms was obtained. The volunteer control subjects who completed the questionnaire were in regular full time employment, with no history of excessive fatigue, on no GI medication, and had no previous GI surgery. Radionuclide measurement of upper GI motility Details and normal ranges of this double isotope test have been previously published [ 8 ]. The solid meal consisted of 100 g of cooked ground beef containing 40MBq in-vivo labelled  99m Tc-sulfur colloid-chicken liver, and the liquid meal consisted of 150 ml of 10% dextrose in water containing with 20 MBq of  67 Ga-ethylenediaminetetraacetic acid (EDTA). All medication (except oral contraceptives) was discontinued for 24 hours prior to each study. The test was performed at 10 am (after an overnight fast) and monitored for at least two hours with the subject in the sitting position with the scintillation camera behind. The study commenced with a standardised oesophageal clearance study (solid bolus) followed by eating the solid meal and then immediately drinking the glucose solution. Each study was continued for at least 2 hours. Oesophageal clearance was expressed as time to 95% clearance (ref range < 93 sec) [ 9 ], Liquid gastric emptying as half-clearance time (ref 4–31 minutes) and solid emptying as amount remaining at 100 min (ref 4–61%). The GI questionnaires were compared between CFS and control by Chi 2 , and Gastric emptying indices compared with historical normal range (t test comparison of means), and correlated with the mean symptom score (± SD). The Study was approved by The Human Research Ethics Committee of the Royal Adelaide Hospital and informed consent given by the subjects.
Methods
Subjects Consecutive patients with CFS who met the Fukuda criteria [ 6 ] for CFS were all seen by a single physician (RB). Patients with any medical condition which could account for chronic fatigue, a BMI > 30, previous GI surgery or medication affecting the rate of gastric emptying were excluded. Overt psychiatric disease was excluded at the interview. The patients were asked to self assess their percentage reduction in activity from prior to the onset of CFS as a marker of severity. Gastro-Intestinal symptoms were evaluated in patients and controls by a standard questionnaire prior to the gastric emptying studies [ 7 ]. Symptoms were divided into " oesophageal " (dysphagia, heart burn, acid regurgitation), " gastric ": (anorexia, nausea, early satiety, bloating, abdominal distension, intermittent abdominal pain), " other " frequency of bowel actions, consistency of stools, presence or absence of diarrhoea, urgency and timing. Symptoms were scored. 0, none, 1, mild (symptom could be ignored), 2, moderate (symptom could not be ignored, but did not influence daily activities), 3, severe, (symptom influenced daily activities). A mean symptom score (maximum score 3) for the 6 gastric symptoms, and 3 oesophageal symptoms was obtained. The volunteer control subjects who completed the questionnaire were in regular full time employment, with no history of excessive fatigue, on no GI medication, and had no previous GI surgery.
Subjects
Consecutive patients with CFS who met the Fukuda criteria [ 6 ] for CFS were all seen by a single physician (RB). Patients with any medical condition which could account for chronic fatigue, a BMI > 30, previous GI surgery or medication affecting the rate of gastric emptying were excluded. Overt psychiatric disease was excluded at the interview. The patients were asked to self assess their percentage reduction in activity from prior to the onset of CFS as a marker of severity. Gastro-Intestinal symptoms were evaluated in patients and controls by a standard questionnaire prior to the gastric emptying studies [ 7 ].Symptoms were divided into " oesophageal " (dysphagia, heart burn, acid regurgitation), " gastric ": (anorexia, nausea, early satiety, bloating, abdominal distension, intermittent abdominal pain), " other " frequency of bowel actions, consistency of stools, presence or absence of diarrhoea, urgency and timing.oesophagealgastricotherSymptoms were scored. 0, none, 1, mild (symptom could be ignored), 2, moderate (symptom could not be ignored, but did not influence daily activities), 3, severe, (symptom influenced daily activities). A mean symptom score (maximum score 3) for the 6 gastric symptoms, and 3 oesophageal symptoms was obtained.The volunteer control subjects who completed the questionnaire were in regular full time employment, with no history of excessive fatigue, on no GI medication, and had no previous GI surgery.Radionuclide measurement of upper GI motility Details and normal ranges of this double isotope test have been previously published [ 8 ]. The solid meal consisted of 100 g of cooked ground beef containing 40MBq in-vivo labelled  99m Tc-sulfur colloid-chicken liver, and the liquid meal consisted of 150 ml of 10% dextrose in water containing with 20 MBq of  67 Ga-ethylenediaminetetraacetic acid (EDTA). All medication (except oral contraceptives) was discontinued for 24 hours prior to each study. The test was performed at 10 am (after an overnight fast) and monitored for at least two hours with the subject in the sitting position with the scintillation camera behind. The study commenced with a standardised oesophageal clearance study (solid bolus) followed by eating the solid meal and then immediately drinking the glucose solution. Each study was continued for at least 2 hours. Oesophageal clearance was expressed as time to 95% clearance (ref range < 93 sec) [ 9 ], Liquid gastric emptying as half-clearance time (ref 4–31 minutes) and solid emptying as amount remaining at 100 min (ref 4–61%). The GI questionnaires were compared between CFS and control by Chi 2 , and Gastric emptying indices compared with historical normal range (t test comparison of means), and correlated with the mean symptom score (± SD). The Study was approved by The Human Research Ethics Committee of the Royal Adelaide Hospital and informed consent given by the subjects.
Radionuclide measurement of upper GI motility
Details and normal ranges of this double isotope test have been previously published [ 8 ]. The solid meal consisted of 100 g of cooked ground beef containing 40MBq in-vivo labelled  99m Tc-sulfur colloid-chicken liver, and the liquid meal consisted of 150 ml of 10% dextrose in water containing with 20 MBq of  67 Ga-ethylenediaminetetraacetic acid (EDTA). All medication (except oral contraceptives) was discontinued for 24 hours prior to each study. The test was performed at 10 am (after an overnight fast) and monitored for at least two hours with the subject in the sitting position with the scintillation camera behind. The study commenced with a standardised oesophageal clearance study (solid bolus) followed by eating the solid meal and then immediately drinking the glucose solution. Each study was continued for at least 2 hours. Oesophageal clearance was expressed as time to 95% clearance (ref range < 93 sec) [ 9 ], Liquid gastric emptying as half-clearance time (ref 4–31 minutes) and solid emptying as amount remaining at 100 min (ref 4–61%).The GI questionnaires were compared between CFS and control by Chi 2 , and Gastric emptying indices compared with historical normal range (t test comparison of means), and correlated with the mean symptom score (± SD).The Study was approved by The Human Research Ethics Committee of the Royal Adelaide Hospital and informed consent given by the subjects.Results Thirty-two (32) CFS patients (22F), with a mean age of 38.5 years had gastric emptying studies. Forty-five (45) control subjects undertook the questionnaire. The demographic details of the controls vs. patients are shown in table  1  Gastro-intestinal symptoms were more common in the CFS group (mean symptom score {MSS] 1.01 ± 0.87) than controls (MSS 0.24 ± 0.34) (table  2 ). Table 1 Characteristics of CFS subjects vs controls. (SD) CFS CONTROLS Number 32 45 Sex F 22, M10 F 37, M 8 Age (yr) 38.5 ± 13.9 34.4 ± 8.5 Weight Kg 68.1 ± 12.1 71.8 ± 11.6 Duration CFS (yr) 9.5 ± 6.8 Severity, % reduction activity 65 Smoke % 18 17.8 Table 2 Percentage frequency of any gastrointestinal symptoms. CFS % (n = 32) CONTROLS % (n = 45) GASTRIC Abdominal discomfort 39 22. Fullness after small meal 70 31* Nausea 67 15* Abdominal pain 76 27* Loss of appetite 42 12* Vomiting 22 2* OESOPHAGEAL Acid regurgitation 30 28 Heart burn 48 27 Swallowing difficulty 45 9* OTHER Bowel movements/ day (mean) 1.6 1.2 Constipation % 26 30 Consistency Formed % 67 80 Loose/Watery % 33 20 Nocturnal diarrhoea % 21 0* Faecal Urgency % 51 16* * indicates symptoms more frequent in CFS group p <.05, Chi 2 The overall, grouped gastric emptying studies of CFS subjects showed no significant slowing of oesophageal clearance p = 0.45 from the control population, and no significant correlation between emptying and oesophageal symptom score (r = 0.15) although 5 of the symptomatic and 2 of the asymptomatic subjects 7/32 (22%), were slower than the 95% confidence limits, (fig  1 ), this did not reach statistical significance. The major abnormality shown is a delay in the emptying of the liquid phase in 23/32 72% of the patients, whereas 12/32 (38%) of solid emptying was delayed compared with the historic controls (t comparison of means, figs  2  and  3 , group p ≪ 0.005). When the gastric emptying results were compared to the mean symptom score there was a highly significant correlation of solid (r = 0.81) and liquid (r = 0.65) delay which increased with the symptom score (p ≪ 0.001). Figure 1 Oesophageal clearance time compared with oesophageal symptoms in Chronic Fatigue Syndrome. (Shaded area represents 95% confidence limit of normal reference range) Figure 2 Per-cent gastric retention of solid food compared with mean symptom score in chronic fatigue syndrome. (Shaded area represents 95% confidence limit of normal reference range) Figure 3 Time to 50% gastric emptying of liquid compared with mean symptom score in chronic fatigue syndrome. (Shaded area represents 95% confidence limit of normal reference range)
Results
Thirty-two (32) CFS patients (22F), with a mean age of 38.5 years had gastric emptying studies. Forty-five (45) control subjects undertook the questionnaire. The demographic details of the controls vs. patients are shown in table  1  Gastro-intestinal symptoms were more common in the CFS group (mean symptom score {MSS] 1.01 ± 0.87) than controls (MSS 0.24 ± 0.34) (table  2 ).Characteristics of CFS subjects vs controls. (SD)Percentage frequency of any gastrointestinal symptoms.GASTRICOESOPHAGEALOTHER* indicates symptoms more frequent in CFS group p <.05, Chi 2The overall, grouped gastric emptying studies of CFS subjects showed no significant slowing of oesophageal clearance p = 0.45 from the control population, and no significant correlation between emptying and oesophageal symptom score (r = 0.15) although 5 of the symptomatic and 2 of the asymptomatic subjects 7/32 (22%), were slower than the 95% confidence limits, (fig  1 ), this did not reach statistical significance. The major abnormality shown is a delay in the emptying of the liquid phase in 23/32 72% of the patients, whereas 12/32 (38%) of solid emptying was delayed compared with the historic controls (t comparison of means, figs  2  and  3 , group p ≪ 0.005). When the gastric emptying results were compared to the mean symptom score there was a highly significant correlation of solid (r = 0.81) and liquid (r = 0.65) delay which increased with the symptom score (p ≪ 0.001).Discussion G-I symptoms are common in patients with CFS. Abdominal pain is distressing [ 10 ], often requiring analgesia for relief. A previously unrecorded symptom in CFS patients is nocturnal diarrhoea, which disrupts an already disturbed sleep pattern. The most common upper GI symptom is fullness and bloating after a small meal. The usual medical explanation for the gut symptoms is 'irritable bowel'. Unless specific G-I questions are put to the CFS patient they will not spontaneously discuss these symptoms. An abnormality in solid or liquid emptying or combinations of these study parameters was more common in the more symptomatic patients, and liquid was more frequently affected. This is the opposite of the abnormality seen in diabetic subjects [ 8 ], where the major abnormality, delay in the solid phase of gastric emptying has been ascribed to autonomic dysfunction or hyperglycaemia. A group of elderly subjects with a number of neurological defects showed a delay in the liquid rather than the solid emptying [ 11 ]. Symptoms and delayed gastric emptying in diabetic gastroparesis studies have not correlated well. In this study there is a good correlation with symptoms. The commonest of these was early satiety, fullness and bloating after eating. There was though a poor correlation with oesophageal symptoms and a disorder of oesophageal emptying. GI motility is complex, with central, local neuromuscular and humoral influences. Non-specific endocrine disturbances have been demonstrated in CFS, but the relevance of these is unknown with regard to GI disturbances. Skeletal muscle fatigue appears to be of central rather than peripheral origin, but again it is not known whether this may be extrapolated to visceral muscle. Inconclusive central changes have been documented. The impact of disturbed sensory function is unknown, and this could also involve peripheral nerves or the central processing of sensory information. Diagnostically, there is overlap between CFS, functional dyspepsia and fibromyalgia and all may be related to abnormal sensory processing [ 10 , 12 , 13 ]. Altered gastric emptying has been shown in association with irritable bowel syndrome [ 14 ].
Discussion
G-I symptoms are common in patients with CFS. Abdominal pain is distressing [ 10 ], often requiring analgesia for relief. A previously unrecorded symptom in CFS patients is nocturnal diarrhoea, which disrupts an already disturbed sleep pattern. The most common upper GI symptom is fullness and bloating after a small meal. The usual medical explanation for the gut symptoms is 'irritable bowel'. Unless specific G-I questions are put to the CFS patient they will not spontaneously discuss these symptoms.An abnormality in solid or liquid emptying or combinations of these study parameters was more common in the more symptomatic patients, and liquid was more frequently affected. This is the opposite of the abnormality seen in diabetic subjects [ 8 ], where the major abnormality, delay in the solid phase of gastric emptying has been ascribed to autonomic dysfunction or hyperglycaemia. A group of elderly subjects with a number of neurological defects showed a delay in the liquid rather than the solid emptying [ 11 ].Symptoms and delayed gastric emptying in diabetic gastroparesis studies have not correlated well. In this study there is a good correlation with symptoms. The commonest of these was early satiety, fullness and bloating after eating. There was though a poor correlation with oesophageal symptoms and a disorder of oesophageal emptying.GI motility is complex, with central, local neuromuscular and humoral influences. Non-specific endocrine disturbances have been demonstrated in CFS, but the relevance of these is unknown with regard to GI disturbances. Skeletal muscle fatigue appears to be of central rather than peripheral origin, but again it is not known whether this may be extrapolated to visceral muscle.Inconclusive central changes have been documented. The impact of disturbed sensory function is unknown, and this could also involve peripheral nerves or the central processing of sensory information.Diagnostically, there is overlap between CFS, functional dyspepsia and fibromyalgia and all may be related to abnormal sensory processing [ 10 , 12 , 13 ]. Altered gastric emptying has been shown in association with irritable bowel syndrome [ 14 ].Conclusions These observations indicate that there is measurable disturbance in upper gut motility corresponding with symptoms in CFS. Although the cause for these findings is not apparent in this study, the more prominent delay in liquid rather than solid emptying may point to a central rather than a peripheral aetiology. The gastro-intestinal tract and function should be properly investigated and the symptoms not necessarily be ascribed to irritable bowel syndrome.
Conclusions
These observations indicate that there is measurable disturbance in upper gut motility corresponding with symptoms in CFS. Although the cause for these findings is not apparent in this study, the more prominent delay in liquid rather than solid emptying may point to a central rather than a peripheral aetiology. The gastro-intestinal tract and function should be properly investigated and the symptoms not necessarily be ascribed to irritable bowel syndrome.Competing interests The author(s) declare that they have no competing interests.
Competing interests
The author(s) declare that they have no competing interests.Authors contribution RB examined the patients and analysed the clinical data, BC performed the Nuclear Medicine studies, drafted the manuscript and performed the statistics. Both read and approved the final manuscript.
Authors contribution
RB examined the patients and analysed the clinical data, BC performed the Nuclear Medicine studies, drafted the manuscript and performed the statistics. Both read and approved the final manuscript.Pre-publication history The pre-publication history for this paper can be accessed here:
Pre-publication history
The pre-publication history for this paper can be accessed here: