Psychometric analysis and validation of the Persian translation of the systemic sclerosis questionnaire (SySQ)

Scleroderma is a complex multisystem disorder that could have effects on the quality of patients' lives. This study was conducted by determining the psychometric properties of the Persian version of the systemic sclerosis questionnaire (SySQ) that specifically assesses indications and functional limitations of scleroderma patients.

In the present cross-sectional study, the method included: translation and back translation. Psychometric properties of the questionnaire including its content and face validity were assessed. Internal consistency with the SySQ (Cronbach's alpha) and reproducibility was by test-retest method. The factor structure of the questionnaire was evaluated using exploratory factor analysis. The convergent validity of the SySQ was assessed using the General Health Assessment Scale (HAQ).

Altogether 32 SySQ items, the internal consistency coefficient (Cronbach's alpha) of the whole tool was 0.906. The content validity index was 0.98 and the content validity ratio was 0.796, there was a significant relationship between the questions and the relevant factors in the factor analysis. The correlation coefficient = 0.953 for the instrument. The correlation of SySQ dimensions with HAQ questionnaire dimensions in convergent validity showed that musculoskeletal dimensions, general condition, and cardiorespiratory of the questionnaire are correlated with all dimensions of the HAQ questionnaire.

The Persian version of the questionnaire SySQ with competency is valid and reliable and is suitable for measuring specific changes in Persian systemic sclerosis patients.