Health-related quality of life (HRQL) and continuous antipsychotic treatment: 3-year results from the schizophrenia health outcomes (SOHO) study

Abstract

Objectives: We investigated the association between continuous antipsychotic use and health-related quality of life (HRQL) 3-year change in the European Schizophrenia Outpatients Health Outcomes (EU-SOHO) study. Methods: EU-SOHO is an observational study of outcomes associated with antipsychotic treatment for schizophrenia in an outpatient setting. HRQL was assessed at study entry and at 6, 12, 18, 24, 30, and 36 months using the EuroQol-5D (EQ-5D). UK population time trade-off (TTO) tariffs were applied to the self-rated EQ-5D health states to calculate HRQL ratings (0 = death, 1 = best). An epoch analysis approach was used as a conceptual framework to analyze the longitudinal data. Follow-up was divided into epochs or periods of continuous treatment. When a patient changed antipsychotic treatment, he or she was considered to have a new observation. Multilevel models were employed to evaluate the association of HRQL with medication and other clinical and sociodemographic variables for each epoch. A total of 9340 patients were analyzed (42.1% women; mean age 40 years). Results: Mean EQ-5D scores increased over time; the largest improvement occurred in the first 6 months (mean increase of 0.19). Longer duration of illness and older age at first treatment were associated with worse baseline EQ-5D scores. Improvements in EQ-5D scores were greater for more socially active patients or those in paid employment. Few significant differences were found between antipsychotic medications. Olanzapine and clozapine were associated with higher HRQL increases. Conclusions: Continuous antipsychotic treatment is associated with important HRQL benefits at 3 years, most of which occurs during the first 6 months. Although some medications are associated with better HRQL outcomes, differences are small. © 2008, International Society for Pharmacoeconomics and Outcomes Research (ISPOR).