Aim: To assess the relationship between mental health and health-related quality of life (HRQL) in the general population, and to map GHQ-12 as a screening test for population psychological distress to a generic health state measure (EQ-5D) in order to estimate health state values and allow deriving quality-adjusted life years.
Methods: Relationship between mental health and HRQL was examined from the 2004 Canary Islands' Health Survey. Participants were classified as probable psychiatric cases according to GHQ-12. HRQL was measured by the EQ-5D index. Multivariate lineal regression analysis was used to examine the association between mental health and HRQL adjusting by socio-demographic variables and comorbidities. A multivariate regression model was built from EQ-5D to estimate health states values using GHQ-12 as exposure.
Results: EQ-5D index scores decreased as the GHQ-12 scores increased. Clinical and socio-demographic factors influenced HRQL without changing the overall trend for this negative relationship. The regression equation explained 43% of the variance. For estimation of utility scores, the model showed a high predictive capacity, with a mean forecast errors of 16%.
Conclusions: HRQL progressively decreased when the probability of being a psychiatric case increased. Findings enable health state values to be derived from GHQ-12 scores for populations where utilities has not or cannot be measured directly.