Psychometric properties evaluation of the Persian version of the self-report outcome scale for lupus disease Lupus_PRO version 1.7.

Purpose: Systemic Lupus Erythematosus (SLE) significantly affects both the quality of life related to health and non-health aspects. This study aims to evaluate the psychometric properties of the Persian version of the Lupus_PRO questionnaire, version 1.7. The questionnaire serves as a specific self-report outcome scale for assessing the treatment outcomes of Lupus disease.

Methods: The Lupus_PRO questionnaire, version 1.7, was translated into Persian using the standard forward-backward method. After being completed by 218 patients with Lupus, the psychometric properties of the instrument were examined. The Convergent and Discriminant Validity of the scale were assessed using Average Variance Extracted and Cross Loadings, respectively. The construct validity of the questionnaire was also evaluated through Confirmatory Factor Analysis (CFA). Cronbach's alpha was calculated to assess the reliability of the questionnaire dimensions.

Findings: Out of the 218 patients with lupus who participated in the current study, 13 (6%) were male, and 205 (94%) were female. The mean (SD) age of participants was 40.29 (10.94) years. The Average Variance Extracted (AVE) for HRQOL and Non-HRQOL constructs, except for the Coping and Cognition dimension, was greater than 0.50, indicating satisfactory convergent validity. The interdimensional correlation coefficient (Discriminant Validity) for each dimension with other questionnaire dimensions was less than 0.10, indicating that the questionnaire has good convergent and discriminant validity. Additionally, the results of the Confirmatory Factor Analysis (CFA) indicated that the questionnaire was a suitable fit. In terms of reliability, Cronbach's alpha for the various questionnaire dimensions ranged from 0.51 to 0.91, indicating good internal consistency.

Conclusion: The Persian version of the Lupus_PRO questionnaire, version 1.7, demonstrates acceptable validity and reliability in the Iranian population. This instrument can effectively measure various aspects of the quality of life in patients with lupus.