Psychometric Properties and Hidden Dimensionality of the Sinhala Version of End Stage Renal Disease Adherence Questionnaire (SINESRD-AQ) Among Patients Receiving Haemodialysis in a Selected Hospital in Sri Lanka

BackgroundAdherence to a complex therapeutic regimen is crucial to maintain the quality of life of patients receiving haemodialysis. End Stage Renal Disease Adherence Questionnaire (ESRD-AQ) is a valid and most widely used instrument to assess all dimensions of treatment adherence among patients receiving in-center haemodialysis. Though the precise evaluation is fundamental, availability of valid and reliable instruments to evaluate treatment adherence is limited in Sri Lanka. Therefore, the purpose of this study was to evaluate the psychometric properties of Sinhala translated version of ESRD-AQ.MethodsThe translation and cultural adaptation of ESRD-AQ underwent forward and back translation, expert committee consolidation and pretesting among patients (n=10). Face and content validity were evaluated with a panel of experts (n=6) and group of patients (n=10). Confirmatory Factor Analysis (CFA) was performed to evaluate construct validity of two subscales of SINESRD-AQ. Subsequent Categorical Principal Component Analysis (CATPCA) was performed to identify a more parsimonious dimensionality to assess treatment adherence behaviors among patients. Ethical approval was obtained from the Ethics Review Committee, Faculty of Medical Sciences, University of Sri Jayewardenepura and Teaching Hospital, Kurunegala, Sri Lanka. ResultsA total of 150 patients with mean age of 54.08±10.78 (±SD) years were included. Majority were males (72.7%). Excellent face and content validity of SINESRD-AQ was reported. The CFA of two subscales of ESRD-AQ demonstrated barely acceptable model fit (SRMR=0.120, CFI=0.913, GFI=0.997, AGFI=0.996, NNFI=0.896). Subsequent CATPCA revealed new dimensionality with five components explaining 74% of the total variance. Convergent validity of new dimensionality was confirmed with Composite Reliability (CR) and Average Variance Extracted (AVE) with the values greater than 0.7 and 0.5 respectively. According to the Fornell Larcker criterion (1971), the square root of AVEs of components were greater than the inter component correlations and heterotrait-monotrait values were less than the threshold of 0.85 demonstrated the discriminant validity of new dimensionality.ConclusionSINESRD-AQ is a valid and a reliable instrument to assess treatment adherence behaviors among Sinhala speaking patients receiving haemodialysis in Sri Lanka. A follow-up CFA is to be performed to confirm the revised dimensionality of SINESRD-AQ.