The Italian version of the Keratoconus Outcomes Research Questionnaire (KORQ): Translation and validation of psychometric properties.
PURPOSE
To develop and validate the Italian version of the Keratoconus Outcomes Research Questionnaire (KORQ).


METHODS
Cross-sectional validation study. Keratoconus patients with routine appointments at the outpatient clinic were consecutively enrolled in conjunction with a sample of non-keratoconus controls for comparison. The Italian translation from the original English version of the KORQ was administered to the patients together with the Italian version of the 25-item version of the National Eye Institute Visual Function Questionnaire (NEI VFQ-25). The reliability and validity of the Italian KORQ were assessed using standardized internationally accepted methods for cultural adaptation and validation of health-related quality of life measures.


RESULTS
One hundred patients were deemed eligible and completed the questionnaires. The Cronbach's alpha coefficient for internal consistency ranged from 0.71 to 0.956 across the subscales. Spearman correlation coefficient and intraclass correlation coefficient of 0.98 showed excellent test-retest reliability. The control group had better scores on every subscale. Statistically significant correlations were found between the KORQ and analogous domain of the NEI VFQ-25 and with disease severity indicators, such as visual acuity, maximum keratometry, and steepest keratometry, thus demonstrating good construct and concurrent validity.


CONCLUSION
The Italian version of the KORQ exhibited excellent internal consistency, test-retest reliability, validity, discriminatory power, and psychometric properties comparable with those of the original English version, and thus may be adopted as a powerful vision-targeted quality of life assessment tool for Italian keratoconus patients.
['Ferrini|Erica|E|https://orcid.org/0000-0002-8569-7331', 'Aleo|Davide|D|', 'Posarelli|Chiara|C|https://orcid.org/0000-0003-0222-5177', 'Albert|Timothy|T|', 'Miccoli|Mario|M|', 'Orrù|Graziella|G|', 'Figus|Michele|M|https://orcid.org/0000-0003-2243-9033']
D003430:Cross-Sectional Studies D006801:Humans D007558:Italy D007640:Keratoconus D017063:Outcome Assessment, Health Care D011594:Psychometrics D011788:Quality of Life D015203:Reproducibility of Results D011795:Surveys and Questionnaires
Keratoconus keratoconus outcomes research questionnaire quality of life vision-related quality of life