Adherence and rehospitalizations in patients with schizophrenia: evidence from Japanese claims data

BACKGROUND The aim of this study is to analyze if there is a relationship between adherence to antipsychotic medication and rehospitalization for patients diagnosed with schizophrenia in Japan. METHODS Based on Japanese claims data, we constructed three patient groups based on their medication possession ratio (MPR). Controlling for potential confounders, a Cox proportional hazard model was employed to assess if medication adherence affects the risk of rehospitalization. RESULTS Patients with good adherence (MPRs from 0.8-1.1) had the lowest rates of admission. Both poor adherence (MPRs <0.8) and overadherence (MPRs >1.1) were associated with a significant higher risk of rehospitalization with hazard ratios of 4.7 and 2.0, respectively. CONCLUSION The results of this study support the notion that good adherence to antipsychotic medication reduces the risk of rehospitalization of schizophrenia patients. Appropriate measures should be taken to improve adherence of schizophrenia patients.