All forms of asbestos are now banned in 52 countries. Safer products have replaced many materials that once were made with it. Nonetheless, many countries still use, import, and export asbestos and asbestos-containing products, and in those that have banned other forms of asbestos, the so-called “controlled use” of chrysotile asbestos is often exempted from the ban. In fact, chrysotile has accounted for > 95% of all the asbestos used globally.We examined and evaluated the literature used to support the exemption of chrysotile asbestos from the ban and how its exemption reflects the political and economic influence of the asbestos mining and manufacturing industry.All forms of asbestos, including chrysotile, are proven human carcinogens. All forms cause malignant mesothelioma and lung and laryngeal cancers, and may cause ovarian, gastrointestinal, and other cancers. No exposure to asbestos is without risk. Illnesses and deaths from asbestos exposure are entirely preventable.All countries of the world have an obligation to their citizens to join in the international endeavor to ban the mining, manufacture, and use of all forms of asbestos. An international ban is urgently needed. There is no medical or scientific basis to exempt chrysotile from the worldwide ban of asbestos. The Collegium Ramazzini first called for a universal ban on the mining, manufacture, and use of asbestos more than a decade ago . All forAll forms of asbestos cause asbestosis, a progressive, debilitating fibrotic disease of the lungs. All forms of asbestos also cause malignant mesothelioma and lung and laryngeal cancers, and may cause ovarian, gastrointestinal, and other cancers . More thAbout 125 million people around the world are exposed to asbestos in their work environments , and manIn 2000, an estimated 43,000 deaths worldwide resulted from malignant mesothelioma, and a much larger number of lung cancer deaths were due to occupational exposures to asbestos . PopulatIn the United Kingdom, at least 3,500 people die from asbestos-related illnesses each year, and this number is expected to increase to 5,000 in future years. Asbestos accounts for more than half of the work-related cancer deaths in Great Britain . The BriNonoccupational, environmental exposure to asbestos from the use of construction materials that contain asbestos is also a serious and often neglected problem throughout the world. In developed countries, large quantities of asbestos remain as a legacy of past construction practices in many thousands of schools, homes, and commercial buildings. In developing countries, where asbestos is used today in large quantities in construction, asbestos-contaminated dust is now accumulating in thousands of communities, with virtually all people burdened with asbestos fibers in their lungs and bodies .Both community-based and industrial exposures to asbestos and asbestiform fibers increase risks for mesothelioma . In a stAsbestos is a general term applied to certain fibrous minerals of two configurations: serpentine and amphibole. The only type of asbestos derived from serpentine minerals, chrysotile , accounts for 100% of the asbestos used in the world today . AmphiboThe asbestos industry has relied on scientific debates over the roles of fiber types, viruses, and genetics in the development of mesothelioma to obfuscate the problem of asbestos-related disease . The risConcern has been raised that mesothelioma deaths might be partly attributable to poliovirus vaccines used during the 1950s and 1960s that were contaminated with simian virus 40 (SV40), a monkey virus that is tumorigenic in rodents . HoweverSome researchers have suggested that susceptibility to asbestos-related diseases is related to genetic differences between individuals within populations. A study of a mesothelioma clustering in Turkey advocated the role of genetic susceptibility and familial inheritance in the etiology of the disease . A genetControversies such as these have helped to make the disease experiences of asbestos-exposed workers and people in asbestos-contaminated communities invisible and uncompensated, allowing the asbestos industry to escape accountability . The proIndustries have the resources to seed the literature with strategic science that is less likely to be subjected to the same scrutiny routinely applied to science that is explicitly case specific . Many arWhen there is consensus in the public health community about the health effects of a compound—particularly one that is as well researched as asbestos—government agencies and other funders are not interested in additional research that will merely demonstrate what is already known. The only people who have an incentive to continue to fund research on the health effects of chrysotile are those with an economic incentive to raise doubt about its harm. Sponsorship by parties involved in litigation leads to an imbalance in the literature . As a reA Conference on Asbestos and Mesothelioma was held in May 2010 and was sponsored by both plaintiff and defense lawyers who paid scientists to come to a resort center to discuss asbestos issues . The conChrysotile represents nearly 100% of the asbestos produced and used worldwide today  and 95% Early suggestions and industry reports that chrysotile might be significantly less dangerous than other forms of asbestos have not been substantiated. Although chrysotile accounts for almost all the asbestos ever used, the asbestos industry continues to claim that asbestos-related cancers are the result of the amphibole varieties . DefendeThe Chrysotile Institute , a registered lobby group for the Quebec asbestos mining industry, takes the position that chrysotile can be handled safely . NumerouThe Some countries have banned forms of asbestos no longer in use anywhere, yet they exempt the use of chrysotile. This exemption reflects the close relationship the asbestos industry has with many governments, the lack of public health information and regulation in these countries, and the lack of compensation for asbestos victims . The tolDespite all that is known about the dangerous and adverse health effects of asbestos, annual world production remains at > 2 million tons . Russia All forms of asbestos are now banned in 52 countries , includiInternational organizations have condemned the continuing use of chrysotile asbestos. In 2006, the WHO called for the elimination of diseases associated with asbestos. The WHO supports individual countries in developing national plans to ban asbestos and eliminate asbestos-related disease, stating that “the most efficient way to eliminate asbestos-related disease is to stop using all types of asbestos” . The IntThe PIC is the core principle of the Rotterdam Convention. This legally binding procedure requires that governments in all countries be provided full information about the risks to health and the environment of each of the hazardous materials regulated by the Convention before importation. Annex III of the Rotterdam Convention lists the chemicals—40 in number—currently covered by the Convention’s PIC requirement: 25 pesticides, 4 severely hazardous pesticide formulations, and 11 industrial chemicals.Repeated efforts to include chrysotile asbestos under the Rotterdam Convention have failed, not because its Chemical Review Committee has not recommended the listing of chrysotile, but because of the Convention’s requirement for unanimity and as a result of the determined opposition of asbestos mining and manufacturing countries. At the 2008 conference of parties on the Convention, Kazakhstan, Kyrgyzstan, Vietnam, Russia, and Zimbabwe opposed listing chrysotile asbestos in Annex III . A few aThe profound tragedy of the asbestos pandemic is that all illnesses and deaths related to asbestos are preventable. Safer substitutes for asbestos exist, and they have been introduced successfully in many nations. Currently, asbestos cement products account for > 85% of world consumption , and in If global use of asbestos were to cease today, a decrease in the incidence of asbestos-related diseases would become evident in approximately 20 years . The asbAn international ban on the mining and use of asbestos is urgently needed. The risks of exposure to asbestos cannot be controlled by technology or by regulation of work practices. Scientists, physicians, and responsible authorities in countries allowing the use of asbestos should have no illusion that “controlled use” of chrysotile asbestos is an effective alternative to a ban on all use of asbestos . Even thTo protect the health of all—now and in future environments—the Collegium Ramazzini again calls on all countries of the world to join in the international endeavor to ban the mining, manufacture, and use of all forms of asbestos.


Sir,Air travel has now become a common mode of transport. A variety of low-cost carriers have made air travel accessible to a larger section of the Indian population. As a result of this, nearly 15 million people travel on domestic airlines each year in India. The exacA 24-year-old male started complaining of shortness of breath and chest discomfort 1 h after the flight took off from the airport. He was immediately given oxygen supplement (4 L/min via a face mask) by the air hostess and she called for help from other crew members. The captain paged for medical assistance on board. The first author being an emergency physician responded to the call. The copassenger, a first-time air traveler, was a known wheezer and not on regular treatment. He had exacerbations during the winter, which subsided with oral bronchodilators. He was suffering from upper respiratory tract infection of 2 days duration. He denied diabetes mellitus, high blood pressure, heart disease and smoking.On examination, he was afebrile, dyspnoeic, tachypnoeic (40/min) tachycardic (123 beats per minute) and cyanosed. His blood pressure was 150/70. On auscultation, the lungs were silent and his heart sounds were audible without murmurs. The abdomen was soft and non-tender. A provisional diagnosis of acute exacerbation of bronchial asthma was made. The patient was shifted from the economy class to closer to the emergency exit for want of space in anticipation of cardiopulmonary resuscitation.Inhaled bronchodilators are one of the most effective therapies for rapid reversal of airway narrowing in acute asthma and, also, have advantages over oral and parenteral routes of delivery. As there was no nebuliser or spacer in the flight, a metered-dose inhaler (MDI) consisting of salbutamol obtained from another copassenger was used. The patient was unable to perform a conventional inhalation maneuver with MDI as he was breathing rapidly.Specific inhalation techniques are necessary for better bronchodilation. An improper inhaler technique can result in decreased drug delivery and potentially reduced efficacy. Also, he was unable to synchronize inspiration with actuation of the MDI or could hold the breath at the end of inspiration, which was routinely recommended for optimum use. As the patient was in impending respiratory failure and in the austere environment, the other best alternative treatment was to use spacer , which allows aerosol delivery better than MDI by circumventing the need for the coordinated actuation of the MDI with inhalation.Moreover, a metaanalysis on bronchodilator delivery in acute airflow obstruction recommends the use of spacer in the treatment of acute airflow obstruction. As thereThe rationale behind addition of a spacer allows aerosol delivery by the MDI to be contained in the spacer for a finite period of time. Trapped aerosol that is inhaled for a few seconds after actuation of the inhaler circumvented the need for the coordinated actuation of the MDI with inhalation and prevented the early landing in the nearest airport.et al. have noted the usefulness of modified plastic bottle as an efficient spacer,[Zar t spacer, which prt spacer,The purpose of this communication is, (a) to emphasize the constraints faced by physicians while providing in-flight assistance to copassengers who become ill on board, (b) to create awareness on physiological adaptation to flight, (c) to reorient our medical education and training to face the clinical challenges of in-flight emergencies and on the availability of the resuscitative drugs and devices in commercial flights and (d) to suggest the need for nebuliser on board if permissible or a spacer with MDI and a pulse oximeter in their emergency kit. Let the survival in sky during medical emergencies not be questionable.


There are many instruments available freely for evaluating obstetric care quality in low-resource settings. However, this profusion can be confusing; moreover, evaluation instruments need to be adapted to local issues. In this article, we present tools we developed to guide the choice of instruments and describe how we used them in Burkina Faso to facilitate the participative development of a locally adapted instrument.Based on a literature review, we developed two tools: a conceptual framework and an analysis grid of existing evaluation instruments. Subsequently, we facilitated several sessions with evaluation stakeholders in Burkina Faso. They used the tools to develop a locally adapted evaluation instrument that was subsequently tested in six healthcare facilities.Three outputs emerged from this process:1) A comprehensive conceptual framework for the quality of obstetric care, each component of which is a potential criterion for evaluation.2) A grid analyzing 37 instruments for evaluating the quality of obstetric care in low-resource settings. We highlight their key characteristics and describe how the grid can be used to prepare a new evaluation.3) An evaluation instrument adapted to Burkina Faso. We describe the experience of the Burkinabé stakeholders in developing this instrument using the conceptual framework and the analysis grid, while taking into account local realities.This experience demonstrates how drawing upon existing instruments can inspire and rationalize the process of developing a new, tailor-made instrument. Two tools that came out of this experience can be useful to other teams: a conceptual framework for the quality of obstetric care and an analysis grid of existing evaluation instruments. These provide an easily accessible synthesis of the literature and are useful in integrating it with the context-specific knowledge of local actors, resulting in evaluation instruments that have both scientific and local legitimacy. Nearly all of the 500 000 maternal deaths worldwide every year occur in low- and middle-income countries (LMICs). Efforts to achieve the 5th Millennium Development Goal have been largely ineffective in regions with the highest maternal mortality, notably sub-Saharan Africa . One strThe first step in improving OC quality is evaluation, to identify problems. There are many freely available instruments for evaluating OC quality in LMICs. However, it is easy to lose one's way among these many instruments, whose evaluation approaches are quite diverse. Also, while healthcare may appear to be a well-defined field, there is nevertheless a certain amount of subjectivity in what is considered important in producing "quality" . There iThis article presents the process we followed to prepare a national evaluation of OC quality in Burkina Faso. We began with a review of existing evaluation instruments, which we then used to develop with stakeholders a locally appropriate evaluation instrument.Burkina Faso is ranked next-to-last on the Human Development Index. Forty-six percent of its population lives under the poverty threshold, 75% of adults are illiterate, and life expectancy is only 51 years . The matIn 2006 the Ministry of Health decided to subsidize OC and emergency neonatal services at 80% to encourage their utilization. Patients now pay only 20% of what they were previously required to pay, which had by far exceeded households' average health expenditures, to the point of being prohibitive for procedures such as caesareans -15. ThisThere appear to be numerous problems in this area. Several studies ,18 have To document OC quality problems precisely and to support informed decision-making, the Burkinabé Public Health Association, working closely with the Ministry of Health, decided to evaluate OC availability and quality in the district health facilities (CMAs and CSPSs). They approached the University of Montreal/CRCHUM  to help develop a context-adapted evaluation instrument.We carried out this study in five stages. First, we reviewed the literature to identify frameworks and evaluation instruments referring to OC quality in LMICs. This was not meant to be a systematic review; nevertheless, we conducted a broad search of both the scientific and the grey literature, as we expected most evaluation instruments to be found in the latter. We began in January 2007 by searching in Ovid MEDLINE for articles published since 1996. Using the combination of MeSH terms "*obstetrics" and "*quality of health care", we identified 32 articles. After reviewing their abstracts, we selected five of them; the remainder were excluded either because they were not about LMICs, dealt with other topics , were in languages other than English or French, or were not accessible. At that stage, we added some well-known seminal documents on OC in LMICs -25 as weSecond, from the literature collected, we inventoried the different components of OC quality and organized them into an exhaustive conceptual framework, as a tool to guide evaluation. "OC quality" is a broad and multifaceted concept. Evaluating it in practical terms requires very precise criteria focused on specific components; hence the value of a conceptual framework that details all the components of OC quality, each of which can serve as an evaluation criterion.Third, we studied the 37 OC quality evaluation instruments using the descriptive-analytical method: we applied the same analytical framework to all the instruments to collect standardized information and to facilitate comparisons . We presFourth, in February and March 2007, we led a deliberative process with stakeholders in Burkina Faso to develop a locally relevant evaluation instrument. Deliberative processes are participative mechanisms for eliciting and combining "scientific" evidence from the literature with "colloquial" evidence from local stakeholders' experience to increase the probability of taking sound and acceptable decisions in a given context . SpecifiFifth, the evaluation instrument was finalized after being tested in two CMAs and four CSPSs, which allowed health professionals in the field to participate in the development process.The results consist of three outputs: 1) a conceptual framework for OC quality; 2) an analysis grid of instruments for evaluating OC quality in LMICs; and 3) an evaluation instrument for OC quality in Burkina Faso.certain aspects of OC quality that are considered the most important in a given context, this choice should be explained in relation to the entire set of possible evaluation criteria. This transparency is even more necessary when evaluation choices are negotiated between different stakeholders. In these circumstances, it is important to use a conceptual framework that is sufficiently exhaustive and operational to guide the selection of evaluation criteria. There is considerable variability in the evaluation instruments and in the literature on OC quality. In the absence of any consensus-supported conceptual framework on OC quality, we refined Donabedian's classical model [structure ; process ; and outcome (the consequences of these services on patients). These levels follow a logical sequence: available resources, put into action, lead to activities that produce results. We inventoried the components of OC quality from the literature and organized them into these three categories, producing a comprehensive conceptual framework in which every item is a potential criterion for evaluating OC quality. Figure Even if the decision is taken to evaluate only al model ,35, whicThis conceptual framework does not judge the components' relative importance, which will, in any case, vary according to stakeholders' perspectives. Rather, it is a tool to support deliberation and the selection of the components to be evaluated in a given context.only mortality or morbidity and nothing else, since they are not, strictly speaking, instruments for measuring OC quality. In short, if we use evaluation criteria from only one level, we cannot infer that the quality thus measured applies to the entire "chain of production" of OC.The causal links between structure, process, and outcome are theoretical and not always verified in reality . A good-Given the large number of OC quality evaluation instruments freely available in English, and often also in French, the problem is not a lack of material, but rather, navigating through it. Thus, we developed an analysis grid to record each instrument's content and evaluation strategy and applied it to the 37 instruments. Additional File The analysis grid can be used to prepare a new evaluation. For instance, if we want to assess quality at the level of OC process, we can easily locate in Table Table The instrument developed to evaluate OC quality in Burkina Faso is presented in its entirety, in French, in Additional File The group used the analysis grid to identify instruments that dealt with each evaluation criterion retained. They consulted these instruments to see how they measured these criteria  and to assess whether they were replicable in Burkina Faso, taking into consideration how OC is organized in this country and the uncertain availability and reliability of data. They recognized that the Burkina Faso instrument could not be as detailed as others because its purpose was to produce a first status report of OC quality in many facilities. The group was rarely able to reuse the questions exactly as they were in the existing instruments. Still, consulting them helped inspire and rationalize the process of developing the new instrument because the group was compelled to consider how to adapt the questions for Burkina Faso. It was also through this consultation that they adopted the "room-by-room walk-through" strategy , in whicFinally, the questionnaire was tested in two CMAs and four CSPSs. Some questions were then rewritten to incorporate service providers' suggestions, to compensate for gaps in information sources, or to control for possible biases in staff responses. Field testing allowed us to identify the most reliable source of information for each question. Certain realities led us to adjust the "room-by-room walk-through" approach. In the CSPSs, where teams and infrastructure are limited, following the patients' route provided no additional information and interrupted the flow of the interview. So there we favoured "classic" staff interviews followed by visits to the maternity ward. In CMAs, the walk-through remains relevant; however, it is not possible to respect the patients' route strictly, because of social sensitivities: starting the evaluation visit with the ambulance drivers, even if they are the patients' first contact with the CMA, is not acceptable to the health workers.Our experience highlights the fact that, even with the abundance of OC quality evaluation instruments specially designed for LMICs, it is rare that an existing instrument will work perfectly, as is, for a new evaluation project.- Evaluation criteria: Our conceptual framework and our analysis grid highlight the multiplicity of possible criteria combinations. Chances are slim that an existing instrument's criteria set perfectly matches the issues under evaluation in a new context.- Evaluation perspective and resource constraints: Many instruments were developed for case studies such as facility supervision or case management review and are therefore very detailed. In Burkina Faso, the evaluation must cover many facilities, but with a restrained budget that limits the time and human resources available for data collection and analysis. The evaluation questions therefore had to be simplified.- Information sources: Documentary sources  are less subject to desirability or memory biases than staff interviews. However, their availability and reliability vary from country to country, and an evaluation instrument that uses them may not be replicable elsewhere.- Organizational and sociocultural realities: The logical reasoning underlying some evaluation instruments occasionally collides with local realities .Still, our experience also demonstrates that the literature , if appropriately presented, can inspire and rationalize the development of a new instrument.The conceptual framework and the analysis grid of evaluation instruments proved useful as syntheses of the OC quality literature. The conceptual framework's components are not new; they come from the literature, where they are amply discussed. What is new, and what helps in rationalizing choices, as we saw with the Burkina Faso working group, is the framework's thoroughness and its structure based on Donabedian's three levels of evaluation of quality of care. Selecting criteria from a defined list involves justifying why the others are not retained.Also, the visual representation of the relationships among the criteria and the levels  is a reminder that evaluation provides information on quality at the level evaluated, but not necessarily at the other levels. As for the analysis grid, our experience with the working group confirmed its ease of use for exploring the broad universe of existing instruments.A key benefit of the conceptual framework and the analysis grid lies in their ability to present, in a synthesized, visual, and easily accessible way, the main elements from the scientific literature. This is especially important because the literature is still not readily available in many LMICs due to problems with Internet connections, cost of subscriptions to scientific journals , and lanWe had two objectives in using a working group: to promote stakeholders' ownership of the evaluation instrument by involving them in its design, and to combine their informal knowledge of the evaluation context with scientific knowledge from the literature. The involvement of the Burkinabé Public Health Association, which launched the initiative, was a given. The Ministry of Health participated as the key decision-maker in matters of quality of care. Other stakeholders, notably funding agencies, also participate in these decisions, but to include them would have been cumbersome: an overly large working group is less effective , and devThe literature and the stakeholders' context-specific knowledge were easily integrated. Members of the working group appreciated the process and understood well and appropriated the lessons from the literature, such as the implications of evaluating OC quality at different levels, i.e., structure, process or outcome. The type of literature used--evaluation instruments and literature on OC--remained concrete and close to the health professionals' experience, and it was presented concisely and visually in a way that supported its direct, practical application, all of which facilitated its positive reception by the group.There were no major disagreements around the development of the instrument, probably due to affinities between the institutions represented; some Association members have worked or are currently working for the Ministry. Minor disagreements were resolved pragmatically in the field testing, based on the feasibility of the evaluation options. The only difficulty was related to the availability of the group's members--busy professionals and decision-makers--for this process that involved several meetings and field visits outside the capital. We overcame this by dividing the group into working subgroups and providing continuous feedback on activities to the whole group.This experience of developing an instrument to evaluate OC quality and availability in Burkina Faso not only underscores the importance of tailoring instruments to the evaluation context, but also shows that existing instruments can inspire and rationalize the process. Two methodological tools produced during this experience could be useful to other evaluation teams: a conceptual framework for OC quality and an analysis grid of existing evaluation instruments. These tools synthesize the literature in a user-friendly format that supports integrating local stakeholders' informal knowledge with the literature to produce evaluation instruments that have both scientific and local legitimacy. In this case, using a deliberative process to integrate these two types of knowledge worked well. It will be important to follow the evaluation currently under way and how its results are used, to see how well this process fulfills its promise of promoting ownership by the local stakeholders.Centre de Santé et de Promotion Sociale ; CMA: Centre Médical avec Antenne chirurgicale ; CRCHUM: Centre de recherche du Centre hospitalier de l'Université de Montréal .OC: obstetric care; LMICs: low- and middle-income countries; CSPS: The authors declare that they have no competing interests.FM, PF, and AB designed the study. FM reviewed the literature on quality of obstetric care, developed the conceptual framework and analyzed the existing evaluation instruments. PF then reviewed the conceptual framework and analysis grid of the evaluation instruments. FM, with assistance from AB, facilitated the process of developing a new evaluation instrument in Burkina Faso, including the pre-test. JdDS played an important role in the development and pre-testing of the instrument. FM wrote the first draft of the manuscript which was then critically revised by PF, AB, and JdDS. All authors read and approved the final manuscript.The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1472-6963/10/20/prepubLiterature review: Components of obstetric care quality. Detailed description of the components of obstetric care quality inventoried from the literature.Click here for fileAnalysis grid of instruments to evaluate the quality of obstetric care in low- and middle-income countries. A grid recording the respective content and evaluation strategy of 37 instruments.Click here for fileInstrument to evaluate the availability and quality of obstetric care in Burkina Faso. The instrument developed to evaluate OC quality in Burkina Faso presented in its entirety, in French.Click here for file


The Transition cost accounting system integrates clinical, resource utilization, and financial information and is currently being used by several hospitals in Canada and the United States to calculate the costs of patient care. Our objectives were to review the use of hospital-based cost accounting systems to measure costs of treatment and discuss potential use of the Transition cost accounting system in health services research. Such systems provide internal reports to administrators for formulating major policies and strategic plans for future activities. Our review suggests that the Transition cost accounting information system may useful for estimating in-hospital costs of treatment. Recent technological innovations and the increasing complexity of medical care in Canada and the United States (US.) have emphasized the need for a cost-effective approach to the care of patients admitted to health care institutions. National-level data indicate that between 1960 and 2002 the proportion of gross domestic product spent on health care increased from 5.5% to 9.9% in Canada and from 5.3% to 14.6% in the US. [Generic per diem costs are daily dollar rates that represent the average cost of one hospitalization day irrespective of the patient's medical condition. Specialty per diem costs are daily dollar rates established for specific hospital departments and represent the average cost of hospitalization in specific departments. Costs per weighted case capture the cost of hospitalization of a patient in a specific condition and are usually classified according to clinical diagnoses. In spite of the availability of such estimates in many hospitals, these rates represent measurements that may be inaccurate for research purposes. Costs per weighted case assume that each patient consumes the same mix of services, and inter-patient variability is not captured [Traditionally, sources of information for estimating costs of treatment in Canadian and US. hospitals included generic per diem costs, specialty per diem costs, and costs per weighted case . Genericcaptured . When uscaptured . The coscaptured .A more accurate method for assessing the costs of health care services is that of "top-down" costing. This method is largely used by US. hospitals and involves breaking down department expenditures to obtain procedure-level costs . The mosAnother method for estimating costs of in-hospital treatment is that of "bottom-up" costing. Bottom-up costing is used partially in Australia and as a standard in Germany . This coA practical and potentially accurate method that hospitals have started to adopt to estimate costs is that of hospital cost accounting systems. Hospital cost accounting systems are software systems that integrate resource utilization and financial data already recorded in other hospital information system databases. These databases include the hospital Billing System, Payroll System, General Ledger System, and from individual departments' resource utilization databases . The useThe Transition system framework views hospital activity as a three-stage process . In the Using the Transition system software, detailed patient-level demographic, clinical, resource utilization, and cost data are integrated into a single database. For each patient, demographic and clinical data are extracted from the hospital Medical Records system and transferred into the Transition system data warehouse. These data include information from the patient's discharge summary such as the length of hospital stay, primary and secondary clinical diagnoses, and principal and secondary procedures. Unit costs are then associated with individual products and services used in the treatment of a patient, and the aggregate of these costs represents the patient's total costs of treatment within the hospital.An understanding of the Transition System methodology is important in order to assess the accuracy of the cost estimates provided by the system. In addition, understanding the methodology is important in order to recognize how the system can be used to undertake cost studies in health services research. The following is a detailed description of the 6-step Transition system methodology used to estimate total unit costs of products and services used in in-hospital patient care .Direct cost centers are patient care departments  that directly provide services to patients, and the costs incurred by these departments are called direct costs. Indirect cost centers are hospital overhead departments , and the costs incurred by these departments are called indirect costs.In the first step of the Transition system methodology, hospital departments are categorized as either direct or indirect cost centers Figure . Each deIntermediate products are department specific and may represent either a product  or a service  or a combination of products and services used in patient care. One example of an intermediate product that is a product includes the medications provided by the pharmacy or a hospital gown from central supplier. Intermediate products that are services include a cardiopulmonary resuscitation in the emergency department or nursing care in the intensive care unit. Examples of intermediate products that combine products and services include a coronary angioplasty in the cardiac catheterization laboratory or a chest x-ray in the department of radiology.In the second step, intermediate products are formed by grouping the services and procedures provided in the patient care departments Figure . IntermeHospital and department managers have complete discretion in the definition of intermediate products since intermediate products defined in the Transition system must directly mirror the activities that are recorded on patient records. Hospitals use the definitions of the intermediate products defined in their patient care systems  and can therefore identify the specific patient for whom each intermediate product was recorded. Typically, US. hospitals use the definitions from their billing system for intermediate product identification.Direct labor costs are costs related to the actual labor of individual employees within the department . Direct materials costs are all department-level non-labor costs that become part of the patient care process . Direct costs may be classified as fixed or variable costs depending on their responsiveness to fluctuations in volume.In the third step, estimations of the relative direct costs of each department's intermediate products are derived Figure . Direct In order to estimate an intermediate product's direct costs, the weighted procedure method is employed. With this method, every intermediate product is assigned a number of relative value units (RVUs). The RVU represents the intermediate product's estimated consumption of equipment, supplies, and personnel time. In other words, RVUs are an expression of the relative direct costs of one intermediate product to another within a given patient care department .RVUs can be calculated based on nationally available standards or based on actual cost data. In Canada, for example, labour RVUs are nationally or provincially engineered time values which are mandated by the Ministry of Health. Alternatively, labor RVUs are also obtained based on actual minutes of time as recorded during the performance of the procedure. Supplies use an RVU calculated based on the average actual cost for the supplies normally used to perform the activity. RVUs for prescribed medications are based on the actual costs to the department.The fixed and variable direct costs of a single RVU can be calculated once RVUs have been allocated to every intermediate product within a department. Costs are calculated by dividing the department's total fixed and variable costs, respectively, by the department's total number of RVUs used throughout a period. The variable and fixed direct cost of each intermediate product can subsequently be estimated by multiplying the intermediate product's assigned variable and fixed RVUs by the cost of a single RVU. For example, a department with 100 RVUs and total direct and indirect costs of $20,000 and $10,000, respectively, will allocate $200 of direct costs and $100 of indirect costs for each RVU. An intermediate product to which the department assigned 3 RVUs will therefore represent a total cost of $900, or $600 in direct costs and $300 in indirect costs.cost pool is any grouping of costs to be allocated, and a base, or cost driver, is a criterion upon which the allocation is to be made [application rate is determined to allocate the total costs of an indirect cost center to a number of direct cost centers. For example, the total costs of a hospital's housekeeping services are usually assigned according to square footage. An application rate would then be determined by dividing total hospital housekeeping costs by total hospital square footage. A rate of $0.50/square foot, for example, indicates that each department will be allocated $0.50 per square foot for housekeeping services provided. While for some indirect cost pools, such as housekeeping, a fairly accurate and plausible allocation basis can be found , many other indirect costs are much more difficult to allocate in a plausible way. The costs of central administration are one example of indirect costs that are difficult to distribute.In the fourth step of the Transition methodology, application rates are identified in order to assign indirect costs to direct cost centers Figure . A base  be made . Using tIn the fifth step, indirect cost centers are allocated using an allocation algorithm Figure . The steIn the sixth step, the indirect costs that were previously assigned to patient care departments are allocated, within each department, to intermediate products Figure . The RVUUsing the Transition system methodology, there are several potential sources of measurement error when estimating the unit costs of products and services. Bias may occur when intermediate products are identified and when direct and indirect dollar values are assigned to each intermediate product. In the second step of the Transition system methodology, procedures and services provided in patient care departments are selected and grouped into discrete intermediate products. The identification of the intermediate products at each department is generally based on the assumption that a relatively small number of procedures and services make up a high percentage of the department's costs. Department managers generally follow the "80/20 rule" thereby identifying the 20% of a department's products and services that account for 80% of its costs . NonetheMeasurement bias may also arise due to misclassification of fixed and variable costs. In the third step of the Transition system methodology, the RVUs of individual intermediate products are estimated based on the total resources consumed when the product or service is used in patient care. The potential for measurement bias arises because a portion of the product's consumption of fixed costs may be considered as variable costs and, conversely, variable costs related to the product may be considered as fixed costs. Depending on the circumstances, the variable and fixed costs of a given intermediate product may be either overestimated or underestimated.Another potential source of measurement bias arise from the incorrect allocation of cost. For example, in the fourth step of the Transition system methodology, application rates are identified in order to allocate indirect costs to direct cost centers. Ideally, indirect costs should be allocated based on cost drivers that cause the minimum amount of distortion in cost allocation. Cost drivers used for allocating indirect costs typically include square footage, pounds of laundry, patient days, or total direct costs incurred by the department. The potential for measurement bias arises here because financial managers may allocate indirect costs to direct cost centers based on imperfect cost drivers. For example, indirect costs may be allocated to direct cost centers based on the total direct costs incurred by the patient care departments. In such cases, a given patient care department may be allocated a bigger or smaller portion of indirect costs than is truly appropriate. Consequently, indirect costs of individual intermediate products will be overestimated or underestimated depending on the circumstances.Incorrect allocation of algorithms is another potential source of measurement bias in costing accounting systems. In the fifth step of the Transition system's analysis, an allocation algorithm is used in order to allocate indirect costs to direct and indirect cost centers. A common algorithm for allocating indirect costs to direct cost centers is the step-down method. Using this method, indirect cost centers are ranked in terms of decreasing amounts of service offered to other centers, and their costs are allocated one at a time in descending order. The order of allocation can have a significant impact on which department ultimately bears the costs of the organization . The potThere are also numerous situations in which service departments service or interact with each other simultaneously . For exaInter-observer variation results from inconsistencies between different individuals recording the data, and intra-observer variations results from inconsistencies by the same observer on different occasions [Transition's various applications access the same central, single database, or Transition data warehouse. The system thus offers a comprehensive clinical and financial database for both hospital inpatients and outpatients. Raw data are transferred into Transition from "feeder systems" such as the hospital's General Ledger (resource utilization data), Medical Records , and Billing systems . The assessment of the accuracy of Transition's financial, clinical, and resource utilization information must therefore consider two major sources of measurement error. The first concerns the accuracy of the original data, i.e. the extent to which the data in the feeder systems are recorded precisely and without bias. ccasions . The secTo examine the accuracy of the data transferred from the feeder systems, we examined the results of an audit performed at one US. hospital. Our previous study suggests that the Transition data warehouse is likely to contain information that is as accurate as that recorded in its feeder systems. This analysis sought to assess the magnitude of discrepancies between information available in the Transition data warehouse and its feeder systems. At this US. hospital, utilization and financial data were compared between the Transition system and its three major feeder systems: the Medical Records system, the Billing System, and the General Ledger system. Documentation from the auditing of the feeder systems at this US. hospital suggests that the accuracy of data is not likely to be compromised when information is transferred from one system to another.The standardized use of clinical information systems in Canadian and US. hospitals suggests that their Medical Records systems are also likely to contain data that are accurate . Using tDifferences in the classification of direct and indirect cost centers may arise if hospitals outsource patient care services to independent contractors. Consider two hospitals, for example, where one hospital provides on-site computed tomographic scans while the other hospital purchases these services from an outside supplier. For the first hospital, the costs related to the scans  will be incurred by the radiology department, a direct cost center and will be assigned to individual patients as direct costs. For the second hospital, however, the costs of the scans will be assigned to an indirect cost center and subsequently allocated to direct cost centers. In such cases, costs defined as direct in one organization may be categorized as indirect in another . MisclasIn addition, variations in RVU estimates can also lead to information bias. The weighted procedure method for estimating the RVUs is one method for correcting problem, however, it is a costly and time-consuming endeavor. In fact, this procedure is so costly that most department managers use industry standards rather than computing the RVUs themselves . The useDifferences in the allocation of indirect cost are another source from which information bias may occur. A careful examination of hospital cost centers may disclose the presence of unusual indirect costs at a particular hospital. Costs related to research activities, affiliated medical schools, bad debts, interest expense, or bond interest, for example, may be present in one hospital's indirect cost pool but not in another. The potential for bias may arise if such expenses are not removed from the cost analysis. In such cases, the misclassification is likely to be differential, and the overall difference in costs between the two hospitals will be overestimated. Other potential sources of differential cost misclassification arise when hospitals use different application rates and allocation algorithms to allocate indirect costs to direct cost centers.Once there is an understanding of the Transition System's methodology, the system can be applied in multi-center studies. For example, the Transition system has been used to examine the cost of treatment of abdominal aortic aneurysm (AAA) repair in Canada and the US. . This saSeveral published studies have previously used the Transition cost accounting system to estimate the costs of health care services at individual hospitals ,25-30. IDespite its limitations the Transition cost accounting system may be an important tool for health services research for several reasons. First, patient-level resource utilization information can be used to examine and compare patient management techniques between different physicians, hospitals, and health care systems. Second, unit costs of products and services estimated by the Transition software can be used in the economic evaluation of hospital-based health care interventions. This information may be especially useful for cost of illness studies and for the evaluation of alternative treatment programs through the undertaking of cost effectiveness, cost benefit, and cost utility analyses . Third, The potential use of the Transition system in health services research largely depends on the accuracy of the cost estimates provided by the software. Due to the possibility for error in measuring costs, it is crucial to understand the Transition system methodology for estimating unit costs of products and services. The Transition system has the potential to provide internal reports to administrators for use in formulating major policies and strategic plans for future activities. Although the primary use of hospital cost accounting systems is for internal management purposes, data extracted from these systems may be useful for conducting cost of illness studies and health services research.AA conceived of the manuscript, contributed to the study design and coordination, and drafted and revised the manuscript. NMD, KBF, and JC revised the manuscript. LP and MJE contributed to the study design and manuscript revisions. All authors read and approved the final manuscript.


It was showed that stomatognathic functions correlate with alterations in locomotion, that are detectable through the analysis of loading during walking. For example, subjects with symptoms of Temporomandibular disorders (TMDs) showed a significant higher load pressure on the two feet, respect to health subjects, when cotton rolls were inserted. This previous study appeared to suggest that the alteration of postural loads associated to a particular alteration of stomatognathic condition  is detectable only in TMD's subjects, while it resulted not detectable in health subjects, because in that study, health subjects did not show any significant alteration of postural loads related to the different stomatognathic tested conditions. In other words, in that previous study, in the group of health subjects, no significant difference in postural loads was observed among the different test conditions; while TMD subjects showed a significant higher load pressure on the two feet when cotton rolls were inserted, respect to all the other tested conditions. Thus, the aim of this study was to better investigate these correlations in health subjects without TMD's symptoms, testing other different intra-oral conditions, and to verifywhether an experimentally induced imbalance of occlusion, obtained putting an unilateral cotton roll, could cause an alteration of postural loading on feet during walking.In a sample of thirty Caucasian adult females (mean age 28.5 ± 4.5), asymptomatic for TMDs, when a cotton roll was positioned on the left or the right sides of dental arches, so causing a lateral shift of the mandible, the percentage of loading and the loading surface of the ipsi-lateral foot, left or right, were found to be significantly lower than in habitual occlusion (p < 0.05). Males were not included because of their different postural attitude respect to females. Further studies in a sample of males will be presented.This study showed that in health subjects without TMD's symptoms, an experimentally induced imbalance of the occlusion, obtained through an unilateral cotton roll, is associated to detectable alterations in the distribution of loading on feet surface, during walking. This study adds new data on a previous investigation, recently published,  in whichNow, we are able to add new data to these previous findings, about the changes in the loading on feet, during walking, in health subjects without TMD's symptoms.In this study, an imbalance of the occlusion was experimentally induced in agroup of health subjects without TMD's symptoms, through an unilateral cotton rollinterposed between the upper and the lower teeth, thus generating an asymmetric imbalance of the occlusion. The postural loading on feet during walking was then investigated.This protocol was performed after the first study  from theThe background of this present protocol is that other researchers in literature found some correlations between walking and occlusion in health subjects without TMD's symptoms.For example, Flavel et al. 2003) [003 [2] oEvidence (in cats) was also presented that the electromyographic activity of the jaw closing muscles increases during upwards movements of the head during walking and decreases as the head falls .Fujimoto et al.  also sugFinally, it was also demonstrated that a change in the postural stability of the subject, given for example, by a knee pathology, can generate changes in the function of trunk, neck and masticatory muscles, suggesting an interrelationship between masticatory function and body posture .On the base of this background, the aim of this study was to verify whether, in health subjects without TMD's symptoms, an experimentally induced imbalance of occlusion, obtained putting an unilateral cotton roll, can be associated to an alteration of postural loading on feet during walking.On 1996, it was introduced the Electronic Baropodometer    , the loading pressure (expressed in gr/cm2) and the loading (expressed in percentage for the two sides) on the feet during locomotion in habitual occlusion and with an unilateral cotton roll interposed between dental arches in the right or in the left sides.The variables investigated in this study were: the load surface  cotton roll between the dental arches only in the left side; ii) cotton roll between the dental arches only in the right side; iii) habitual occlusion.The experimentally induced imbalance of occlusion was performed with an unilateral cotton roll midly crushed between the dental arches in one side; in this condition the subject was asked to swallow . The con2) on the theoretical barycentre, the percentage of loading on the left and the right feet and the loading surface (mm2) on the right and the left feet, were recorded as posturographic parameters. The theoretical barycentre was considered as the point whose projection on the ground falls in the middle of the connecting segment between the barycentre of the right and left limbs [For each condition, the mean pressure during walking  was used to perform the data analysis. Each data set was tested for normality using the Skewness test and the Kurtosis test. Through these analyses, parametric methods were used for the hypothesis testing. For each variable, a one way ANOVA was performed to evaluate the existence of significant differences among the three different experimental conditions. Subsequently, and when appropriate, pairwise comparisons, between the experimental conditions were performed by a Tukey HSD and a Bonferroni test. A p value less than 0.05 was accepted for rejection of the null hypothesis.The Statistical Package for Social Sciences programme  resulted associated to a change in the loads on feet during walking Tables , 4 and 5In this study, only females were included in the sample; this was done because of the different postural attitude and walking attitude observed between genders in several studies. On comparing the genders, males and females  showed aThese studies might explain the inclusion of only females in our investigation. The differences in postural loadings between genders will be studies through further investigation, but this topic is beyond the scope of this study.In this study, the cotton rolls were inserted between the dental arches not to distribute the occlusal load over several teeth and minimize the impact of incongruous dental contacts,  but to cIn a previous study , we founIn this study, no condition was tested with deprivation of any interference from visual sensory functionand this could have limited the evaluation of the postural control; this limitation of the study was due to the fact that during walking, the visual sensory function tends to be necessary for the explication of movements . Thus, tIn an adult caucasian sample of females without TMD's symptoms, the percentage of loading and the loading surface on the right and the left feet resulted to be influenced by an experimentally induced imbalance of occlusion given by a single cotton roll positioned in the right or the left dental arches, respectively. Specifically, when a single cotton roll was positioned in the right dental arch, the percentage of loading and the loading surface on the right foot resulted significantly lower than in habitual occlusion.In addition, when a single cotton roll was positioned in the left dental arch, the percentage of loading and the loading surface on the left foot resulted significantly lower than in habitual occlusion (p < 0.001).The present findings provided some insights about the association of stomatognathic inputs and locomotion, evidencing that also in health subjects without TMD's symptoms, there are detectable interrelationships between occlusion and locomotion, that were not found in a previous study from the same researchers .Antonella Polimeni is a Full Professor at University La Sapienza and Matteo Saccucci is a Staff member at the Unit of Orthodontics at University La Sapienza.The authors declare that they have no competing interests.ST (first author) conceived the study, carried out the analysis of posturographic data, participated in the selection of subjects and performed the statistical analysis; she drafted the manuscript. FF revised the final manuscript. All authors read and approved the final manuscript.


A number of previous studies have investigated various predictors for being granted a disability pension. The aim of this study was to test the efficacy of sick-leave track record as a predictor of being granted a disability pension in a large dataset based on subjects sampled from the general population and followed for a long time.Data from five ongoing population-based Swedish studies was used, supplemented with data on all compensated sick leave periods, disability pensions granted, and vital status, obtained from official registers. The data set included 8,218 men and women followed for 16 years, generated 109,369 person years of observation and 97,160 sickness spells. Various measures of days of sick leave during follow up were used as independent variables and disability pension grant was used as outcome.There was a strong relationship between individual sickness spell duration and annual cumulative days of sick leave on the one hand and being granted a disability pension on the other, among both men and women, after adjustment for the effects of marital status, education, household size, smoking habits, geographical area and calendar time period, a proxy for position in the business cycle. The interval between sickness spells showed a corresponding inverse relationship. Of all the variables studied, the number of days of sick leave per year was the most powerful predictor of a disability pension. For both men and women 245 annual sick leave days were needed to reach a 50% probability of transition to disability. The independent variables, taken together, explained 96% of the variation in disability pension grantings.The sick-leave track record was the most important predictor of the probability of being granted a disability pension in this study, even when the influences of other variables affecting the outcome were taken into account. In Sweden, all residents are covered by National Social Insurance, managed by the National Social Insurance Agency, a government agency. The insurance has several components. One of these is the right to compensation for loss of income owing to sick leave from age 18 until retirement, in the majority of cases at age 65. For sick-leave periods longer than one week a sick leave certificate issued by a physician is required. The purpose of this component of the national social insurance is to provide a close to full income replacement.Unlike the situation in most other industrialised countries, during the period studied, there was no statutory limit on how long a person could be on sick leave with compensation. As the length of the spell increases a decision will sooner or later be taken regarding rehabilitation potential. If this potential is deemed small or non-existent the sick-leave compensation is transformed to a disability pension.From a public health point of view a disability pension as opposed to returning to work is problematic. Several studies have shown that disability pensioners have a lower quality of life ,2, more One of the problems involved in cases of long-term sick leave is to assess the potential for return to work. Potential prognostic factors, such as age, sex, socio-economic factors, time on sick leave, and others have been investigated in several studies -25. CompThe hypothesis of this study was that the sick-leave track record is a strong predictor of being granted a disability pension, possibly modified by other factors. A consequence of the hypothesis would be that subjects who eventually receive a disability pension initially have short-term sickness spells not very different from those of other subjects, but their spells become successively longer, and the intervals between spells successively shorter. Ultimately, the sickness spell intervals disappear and the sick leave benefit is sooner or later converted into a disability pension.Data from five ongoing population studies in Sweden, with baseline investigations between 1980 and 1993, were used. Detailed information about the studies have been presented elsewhere . BrieflyPostal questionnaires were sent to some of these subpopulations, while others answered questionnaires on location in connection with a medical examination. Data from some of the questionnaires, identical in all five subpopulations, was used for this study. The information obtained included age at the baseline examination, sex, and marital status, number of persons in the household unit, education, and smoking habits. For this report, marital status was classified as married/cohabiting or not. Education was classified on a 5-point scale ranging from mandatory education only (= 1) to college or university education (= 5). Smoking habits were classified as currently smoking or not smoking. In addition, for four of the subpopulations, a 5-degree scale was available .Information on all compensated days of sick leave for each individual in the study population from 1 January 1986 until 31 December 2002 was obtained from the National Social Insurance Agency. The data included the first and last day of each sickness spell, irrespective of type and extent of sick-leave benefit. Sick-leave duration was defined as the number of days with compensation regardless of sick-leave extent and type of benefit. Time to the next sickness spell  was defined as the number of non-compensated days from the conclusion of one spell to the start of the next. The annual cumulative number of days with sick leave compensation was defined as cumulative number of days from 1 January to 31 December each year. The two-year cumulative number of days with sick-leave compensation was defined correspondingly, covering any two consecutive years.Information on whether the subjects in the study population had been granted a disability pension from 1 January 1971 until 31 December 2001 was obtained from the National Social Insurance Agency. The data obtained included the decision date, diagnoses, compensation percentage  and type (temporary or permanent) of disability pension. From 1 January 1986 until 31 December 2001 745 men and 753 women received a disability pension (first decision).A detailed distribution of disability pension diagnoses in this cohort has been presented elsewhere . BrieflyData on cause-specific mortality from January 1 of the baseline year until December 31, 2002 was obtained from the National Cause of Death Registry. The reasons for granting the disability pension and causes of death were classified according to the International Classification of Diseases (ICD), versions 8–10 .Informed consent on participation in the study was obtained from all participants, oral in the early part of the study and written later on, as required first by the Research Ethics Committees at Uppsala and Gothenburg Universities and later by the National Research Ethics Board. The Committees and Board approved the study on several occasions during the data collection process.Data was analysed with the SAS statistical programme package . In the The strategy of this study was to analyse the data according to a cohort design using logistic regression. However, a prerequisite for such analysis is a progressive growth of, in this case, sick-leave track data across the follow-up time. Therefore, a guiding pilot study was performed based on a nested case-referent design by which track record data growth could be assessed more easily than in a cohort design. Cases were defined as individuals who were granted a disability pension during follow up (n = 1498). For individuals who did not have a disability pension at baseline and had not received one during follow up and who survived until disability was granted for the pensioners, two sets of referents were matched to the cases, one by age, sex, and geographical area , and the second by age and sex only . The time at which the cases received their disability pension was defined as time 0 for both cases and their referents. Mean and median sick-leave duration for each month from time 0 and backwards until baseline was then calculated in the two groups. The longest follow-up periods covered 192 months. To avoid problems owing to right truncation of unfinished sick leave at time 0, and bias due to the effects of cases waiting for their disability pension decision and being on unlimited sick leave during this time, the follow-up time was ended two years before time 0.As shown in Figure In the main study design, the study population was treated as a cohort followed from 1 January 1986 until 31 December 2001. First, the monthly proportion of individuals on sick leave in relation to individuals open to the possibility of sick leave certification  was calculated and thus successively adjusted for non-exposure. As shown in Figure The analyses of the influence of length of sick leave and other potential predictors on the probability of receiving a disability pension during follow up were performed using logistic regression, providing odds ratios, chi-square measures and degree of explanation based on receiver operating curves. Four analytical models were used, in which being granted a disability pension was used as outcome variable in all models. One of the exposure measures – sickness spell duration, sickness spell interval, annual sick leave days, or two-year sick leave days – was used in each model. In addition, age at baseline, marital status, educational level, household size, smoking habits, calendar time period, and geographical area were entered as explanatory variables in all models. The analyses were stratified for sex. Follow-up time was defined as number of days from baseline prior to disability pension, death, or the end of follow up, whichever came first. The latter two were thus censoring events. To account for the possibility that the results depended on a long sick leave period towards the end of follow up, the analyses were repeated with right truncation of follow-up time of one to ten years. The results were consistently the same.The analyses were performed in two types of dataset. In the analyses using sickness spell duration and interval between sickness spells as exposure measures the observations consisted of single sickness spells updated with outcome, follow-up time and explanatory variables. In the analyses of annual sick leave days and two-year sick leave days the observations consisted of cumulative annual sick leave days or two-year sick leave days, respectively, updated with outcome, follow-up time and explanatory variables. A multilevel analysis indicated no evidence of dependence between observations within the same individual.Only two-tailed tests were used. To account for the many analyses performed, p-values < 0.005 were regarded as statistically significant. Accordingly, 99.5% confidence intervals were used.The characteristics of the study population are presented in Table Sickness spell duration and the cumulative number of sick leave days increased by age. The mean and median sickness spell durations were 16.4 and 3 days among those aged 34 or less, 24.5 and 4 days among those aged 35–44 years, 34.0 and 4 days among those age 45–54, and 33.3 and 4 days among those aged 55–64 years. The corresponding means and medians for cumulative annual sick leave days were 15.7 and 0 days, 17.5 and 0 days, 26.0 and 0 days, and 30.3 and 1 day.The interval means showed a corresponding difference between disability pensioners-to-be and referents as the duration, but in the reverse direction. The cumulative annual sick leave days showed similar variation between pensioners and referents as the sick leave duration data, and so did cumulative two-year sick leave days (data not shown). All four sick leave measures showed significant differences between pensioners and referents, and between the two sexes.Those who became disability pensioners were less often married, had less education, and were smokers to a larger extent than referents. There were no significant differences between the groups regarding household size.After adjustment for the influence of age, men had lower odds than women for disability pension . After adjustment for age, marital status, education, household size, smoking habits and calendar time period there were no significant differences in disability pension rate between women and men. However, since the effects of the adjustment variables were somewhat different among women and men all further analyses were stratified by sex.In the upper half of Table The effects of the model involving cumulative annual sick leave days are shown in the lower part of Table There were no significant differences between the various disability pension diagnoses regarding the sick leave track record as tested in the cohort design. None had a significantly faster or slower progression towards disability pension, as shown in Figure The crude influence of various levels of sick leave duration, annual sick leave days and two-year sick leave days on the cumulative disability pension distribution is presented in Figure The probability of receiving a disability pension described by annual sick leave days, age and sex, adjusted for the influence of marital status, educational level, household size, smoking habit and calendar time period is presented in Figure The study hypothesis was confirmed. Compared with the other significant predictors of a disability pension, i.e., age, educational level, calendar time (business cycle), and geographical area, the various measures of compensated sick leave days had the highest predictive power, and among these annual days of sick leave had the best prognostic precision. Altogether, the exposure variables entered into the model explained 94–97% of the variation in disability pensions, which is extremely high.The study was performed in five large random samples from the general population. The participation rate was satisfactory. We had access to survey data from all the studies, and the survey data used in this study was collected using the same validated instruments in all the underlying studies. The data loss due to missing data among respondents was negligible. Sick leave, disability pensions and mortality data were all obtained from official national registers. Therefore we have no reason to believe that our results are affected by selection or other bias to such an extent that our conclusions would be affected.Several variants of the outcome measures were tested, such as duration and annual sick leave days, accumulated durations and annual sick leave days so far (in relation to date of current sickness spell or year), and mean accumulated duration or annual sick leave days. Duration and annual sick leave days yielded the best predictions. The increase in sickness spell duration and annual sick leave data over time indicated that logistic regression and proportional hazards regression might be appropriate analytical methods. Both were used in models involving sickness spell duration, and gave similar results. In models involving annual sick leave days, hazards regression could not be used since there was no natural time variable. For this reason logistic regression was used throughout.The advantages of the present study include a large study population derived from the general population in three areas of Sweden, access to complete sick leave, disability pension and mortality data, sufficient socio-economic data for adjustment of confounding and variance reducing variables, and a longitudinal design with long-term follow up. Most studies in this area are fairly short-term and therefore seldom cover a whole business cycle. As shown in this study such cycles may have a profound influence on the utilisation of sick leave compensation. The utilisation level in a short-term study may therefore vary with the part of the cycle studied. The scope of the effects of predictors will therefore vary with the cycle. In this study we covered about one and a half cycles, which means that our effect sizes are close to the average across a business cycle.One of the limitations of this study is that the three geographical areas used in this study did not cover northern Sweden, which might be different from the rest of the country. However, the part of the country covered by the study has approximately 75% of the national population.It is well known that there are large differences between countries in the regulation of sick-leave compensation and the granting of disability pension. In spite of these differences, the study of predictors of utilisation of sick leave and disability pensions is an underlying research issue for the scientific community, irrespective of nationality. From a scientific point of view Swedish social insurance has the advantage of being unlimited in terms of days and population covered during the period studied. In countries with limitations, people on sick leave have to find other means of subsistence when the statutory maximum period of compensation ends, eg, go back to work, go on to unemployment support, or social assistance. When they do, their exposure to sick leave ends, the person leaves the tracking system and may be lost to follow up. In the Swedish system a person, who has limited work capacity because of illness, can be followed through the sickness insurance system until full recovery or grant of a disability pension, i.e., there is no data loss due to right truncation of exposure and outcome data.The employer-paid compensation for the first 14 days of sick leave from 1992 on might be a source of bias, since from that time the first day of coverage by national insurance for employees was day 15. The problem cannot be solved by disregarding the first 14 days, since the unemployed and self-employed, receive all their compensation through National Social Insurance. This means that the precision of the first 1–14 days irrespective of sickness spell duration is lower than that of 15 days or more. However, the effect of this source of bias is probably small, since the probability of being granted a disability pension is practically nil at this stage of sick leave, and the first 14 days only make up a small part of the total number of days normally needed for a disability pension.Another source of bias might be that some individuals were granted a disability pension for labour market reasons, and consequently did not have to be on sick leave for very long. Moreover, in 1990–1991 and 1995 the regulations were changed, so that the possibilities of receiving a disability pension for labour market reasons gradually disappeared, which affects the probability of disability pension among subjects 58.5 years or older from 1991 and onwards. However, this was too small a number of subjects to cause any large bias, and most of the possible effect was taken into account by our proxy for the business cycle.A third possible source of bias might be that the National Social Insurance Agency after shorter sick leave periods than normally required during some periods granted disability pension ("drives"). However, even these beneficiaries had fairly long sick leave records, and our observation period was long enough to even out the effects of these periods of deviation from the "norm". It is therefore unlikely that the prognosis function in this report was distorted owing to this potential source of bias.A fourth possible bias is the fact that sick-leave track record data age, and calendar year were updated successively during the follow up, whereas other predictors were measured at baseline only. On the other hand, sex, and education would not have changed if updated, whereas marital status, smoking habits and household size might have changed. The effect of updating would have been a less dominant effect for the track record and a more powerful effect for other predictors. However, firstly, as shown by the chi-square value, the predictive power increase of updating the other predictors would have to be tremendous to even come near that of the track record data, and secondly, the purpose of introducing the other predictors was mainly to make the study population more homogeneous and avoid confounding problems.A number of studies have assessed the effects of sick leave on the probability of being granted a disability pension. Gjesdal and Bratberg in a three-year follow-up study, found that sickness spell durations of 270 days were associated with a 40% probability of disability pension, fairly close to our 285 days for women . A numbeNumerous studies have analysed the effects of other disability pension predictors ,15,34-37It may appear that we found a stronger effect of track record measures and a weaker effect of other variables than in most other studies. This may be due to two circumstances. First, the long-term follow up with growing sick leave measures but constants socio-economic variables, such as educational level, to some extent favoured the sick leave measures. However, the most important explanation is probably that we used Wald's chi-square to grade the importance. Others seem to have used the odds or hazard ratios, where the size depends not only on the effect but also on the grading of the variables. If we had used the odds ratios the sick leave measures had, erroneously, been in the mid-range of the rank order of importance. Our results do not differ very much from others from a qualitative point of view, but the measurement and interpretation of predictor impact differs.We found no differences between the various causes of disability pension regarding the effects of the measures of sick-leave days, indicating that the track record effect is approximately the same whatever the underlying disease. This issue was analysed by Gjesdal and Bratberg  (who useThe main implication of this study is that it is important to avoid granting a disability pension too early in the sick-leave history. In the Swedish setting, with 180 annual sick-leave days there is still 85% probability or more of return to work, and with 365 annual sick-leave days more than 50% return to work probability among persons 50 years or younger, and a 25% probability among those 60 years or younger.In this study the sick-leave track record was the far most important predictor of the probability of being granted a disability pension. Of the possible predictors analysed in this study, cumulative annual sick-leave days had the highest precision. Among other predictors, age, educational level, and the sick-leave spell's position in the business cycle were the strongest, but far weaker than sick-leave track record. We also found support for the underlying hypothesis that the course of sick leave prior to a disability pension begins with short-term sick-leave periods followed by spells increasing in length and with shorter and shorter intervals between them, ending finally with a disability pension.The authors declare that they have no competing interests.All authors designed the study and collected the data in their subpopulations or provided register data. EP, TW and KS obtained additional register data. TW, HW and KS performed the analyses and drafted the manuscript. All authors participated in the discussions of the draft outline and contributed later to revision of texts, tables and figures. All authors have seen and approved the final version of the manuscript.The pre-publication history for this paper can be accessed here: