Psychometric properties of End Stage Renal Disease-Adherence Questionnaire-Sinhalese version among patients receiving haemodialysis

The chronic kidney disease is a leading public health concern, particularly in low-to middle-income countries, while the number of patients receiving haemodialysis is rapidly increasing. Adherence to a complex treatment regimen is vital for those patients on maintenance haemodialysis though the precise evaluation is reported inadequately. This study aimed to evaluate the psychometric properties of Sinhalese version of End Stage Renal Disease-Adherence Questionnaire (SINESRD-AQ) to assess treatment adherence behaviour among patients receiving haemodialysis in a Sri Lankan hospital. The cultural adaptation of ESRD-AQ involved forward and back translation, expert committee consolidation and pretesting among patients (n = 10). Face and content validity of the questionnaire was evaluated using a modified Delphi technique. Construct validity of the subscales of SINESRD-AQ was evaluated using confirmatory factor analysis (CFA). A descriptive cross-sectional study among a consecutive sample of 150 patients receiving haemodialysis in a selected Teaching hospital, Sri Lanka was involved in performing CFA. Reliability was confirmed with test-retest reliability. Excellent face and content validity were reported with Item level content validity index (0.83-1.0), Average Item level content validity index for whole scale (0.93), Item level content validity ratio (0.67-1.0) and modified kappa statistic coefficient (0.81-1.0). CFA of two subscales demonstrated better indices closure to the model fit with five- item two factor model for direct adherence behaviour subscale and eight-item two factor model for attitude/perception subscale. The intra class correlation coefficient of 0.837 (p<0.001) and 0.752 (p<0.001) indicated acceptable test-retest reliability of direct adherence behaviour and attitude/perception subscale respectively. The study confirmed SINESRD-AQ as a valid and reliable measure which enables periodic assessment of treatment adherence behaviour of the patients receiving haemodialysis in a Sri Lankan hospital.