Evaluation the validity of Persian version of Quality of life questionnaire in celiac patients

Abstract

Considering the importance of having a celiac disease-specific measure of the quality of life (QOL) in Persian, the present study aimed to translate celiac disease quality of life questionnaire (CDQOL) into Persian and evaluate its psychometric properties. Methods: In this cross-sectional study, the Forward-Backward translation method was used. The content validation ratio (CVR) and the content validity index (CVI) were used for content validity assessment. The construct validity was assessed by exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) on 220 celiac patients who were selected randomly from the celiac disease (CD) registry database. The correlations between the result of the Persian version of CDQOL (PCDQOL), self-rated QOL, and short form-36 (SF36) were analyzed using the Pearson correlation test. The internal consistency and test-retest reliability were measured through Cronbach’s alpha and intraclass correlation coefficient (ICC). Results: In the present study, 220 celiac patients with the mean age of 35.54±10.29 years participated. The mean CVI, CVR, and impact score of PCDQOL were 0.98, 0.96, and 4.82 respectively. Using EFA, four factors have extracted that had a good fit in CFA (Chi-square/DF=1.74, RMSEA: 0.08, and CFI: 0.90, and NFI: 0.90). The results showed that there was a moderate to the high correlation between PCDQOL, SF36 (r: 0.587, P=0.02), and self-rated QOL (r: 0.64, p<0.001). The questionnaire had high internal consistency (Cronbach alpha: 0.93) and test-retest reliability (ICC: 0.96 [0.86-0.99]).