Validation of Brunei’s Malay EQ-5D Questionnaire in Patients with Type 2 Diabetes

BACKGROUND The Malay spoken in Brunei a South East Asian country where Malay is the national language is distinctive and different from Malay spoken in Malaysia, Singapore and Indonesia. This study aimed to develop a Brunei Malay version of the 5-level EQ-5D questionnaire (EQ-5D-5L) and to assess its psychometric properties among patients with type 2 diabetes mellitus (T2DM). METHODS The Brunei Malay EQ-5D-5L was developed by culturally adapting two existing Malay versions. A total of 154 Bruneians with T2DM completed the questionnaire in two different points of time with one week apart. Known-groups validity of the utility-based EQ-5D-5L index and visual analogue scale (EQ-VAS) was evaluated by comparing subgroups of patients known to differ in health status. Test-retest reliability was assessed using the intraclass correlation coefficient (ICC) or Cohen's kappa. RESULTS As hypothesized, patients known to have 'better' health had higher EQ-5D-5L index scores than those having 'worse' health in all 7 known-groups comparisons. The hypothesized difference in the EQ-VAS scores was observed in only 4 of the 7 known-groups comparisons. Kappa values ranged from 0.206 to 0.446 for the EQ-5D-5L items; the ICC value for the EQ-5D-5L index and EQ-VAS was 0.626 and 0.521, respectively. CONCLUSIONS The utility-based EQ-5D-5L index appears to be valid and reliable for measuring the health of Brunei patients with T2DM. The validity of the EQ-VAS in Brunei requires further investigation.