Mapping the PHQ-8 to EQ-5D, HUI3 and SF6D in patients with depression

Abstract

\n Background There is limited evidence of mapping the clinical instrument to a generic preference based instrument in an Asian patient population. The current study aims to map the eight-item Patient Health Questionnaire depression scale (PHQ) onto the EuroQol fivedimensional (EQ-5D), the Health Utilities Index Mark 3 (HUI3) and the Short Form-6D (SF-6D) which helps to inform future in cost-utility analyses for treatment in depression sample. Methods A total of 249 participants who have completed PHQ-8, EQ5D, SF-6D and HUI3 questionnaires were included in the analyses. A beta regression mixture model was used to map the utility scores. Results The results were compared against two common regression methods including Ordinary Least Square (OLS) and Tobit regression models. The mean age of the sample was 36.2 years (SD=11.1). The mean EQ-5D-3L,EQ-5D-5L, HUI3 and SF-6D utility scores were 0.615, 0.709, 0.461 and 0.607,respectively. The EQ-5D-3L, EQ-5D-5L and SF-6D utility scores were best predicted by the beta mixture regression model consisting of PHQ total sores, PHQ-squared, and covariates including age and gender. The HUI3 was best predicted by the OLS model. Conclusions The current study provides important evidence to clinicians and researchers about the mapping algorithms that can be used in economics evaluation among patients with depression.