Validity of the Malay EQ-5D-3L in the Malaysian Transfusion-Dependent Thalassemia Population

Objective: The objective of this study was to examine the cross-sectional convergent and known-group validity of the Malaylanguage EQ-5D-3L instrument in children and adults with transfusion-dependent thalassemia (TDT). Methods: A cross-sectional health-related quality of life survey involving TDT patients from 12 different treatment centers across Malaysia was conducted using the Malay PedsQL 4.0 Generic Core Scales and the Malay EQ-5D-3L questionnaire. Patients with non-TDT and other hemoglobinopathies were excluded. Convergent, discriminant, and known-group validity of the EQ-5D-3L was assessed against the PedsQL 4.0 Generic Core Scales in children. In the adult population, known-group validity of the EQ-5D-3L was assessed using an a priori hypothesis between patients' demographic characteristics and health outcomes obtained from literature. Results: A total of 370 children and 225 adults were sampled. The mean (standard deviation) EQ-5D-3L scores of the children were 0.892 (0.082) and the adults were 0.887 (0.085). Convergent and discriminant validity was identified when correlated with the PedsQL domain in children. In both groups, known-group validity was evident when comparing groups of patients with reported problems to the group of patients with no reported problems on the EQ-5D-3L domains based on the a priori hypothesis derived from literature. Conclusion: This study found convergent, discriminant, and known-group validity of the Malay EQ-5D-3L in a populationbased sample of patients with TDT. Hence, the instrument is valid for the assessment of health-related quality of life in children and adults with TDT in Malaysia.