Validity and internal consistency of EQ-5D-3L quality of life tool among pre-dialysis patients with chronic kidney disease in Sri Lanka, a lower middle-income country

Objective EQ-5D-3L is a generic QOL tool used mainly in economic evaluations. Burden of Chronic Kidney Disease (CKD) is rising in Sri Lanka. Assessing the validity of generic QOL tools creates new opportunities of their utilization among patients with CKD. Methods A cross-sectional study was conducted among 1036 CKD patients, selected using the simple random sampling technique. The validity was tested with six a-priori hypotheses. These included construct validity assessments, evaluating convergent validity and performing known group comparisons. EQ-5D-3L, Short Form-36 (SF-36), Center for Epidemiological Studies Depression Scale (CES-D-20) and General Health Questionnaire-12 (GHQ-12) were used to assess QOL, presence of depression and psychological distress respectively. Internal consistency of the whole tool and when each item is removed was assessed by Cronbach alpha. Results The response rate was 99.2%. Majority of participants were males (n=646,62.4%) in the age category of 41-60 (n=530; 51.2%). Most were in either stage 4 or 5 of CKD (n=646,75.1%). The summary measures of SF-36, positively and significantly correlated with the EQ-5D-3L index and VAS scores (p<0.001). EQ-5D-3L QOL scores were significantly different between the group with depression and without as measured by CES-D-20 (p<0.001). Assessed using GHQ-12, similar significance was detected between the group with psychological distress and without (p<0.001). The Cronbach alpha was 0.834 and when each item was removed, ranged from 0.782 to 0.832. Conclusion EQ-5D-3L is a valid generic QOL tool with satisfactory internal consistency to be used among CKD patients in the pre-dialysis stage.