Survival analysis of the use of first and second generation antipsychotics among patients suffering schizophrenia: A nationwide population-based cohort study

Background: Few studies have investigated the relationship between the use of different generations of antipsychotics and mortality with contradictory results. The aim of this study is to compare mortality among patients suffering schizophrenia taking different generations of antipsychotics in a nationwide population-based cohort study in Taiwan. Methods: A total of 812 patients suffering newly diagnosed schizophrenia under monotherapy of second generation antipsychotics (SGAs) comprised the group of cases. The matched controls were under monotherapy of first generation antipsychotics (FGAs). Each case was matched individually with their initial antipsychotics prescription calendar year and month, gender, and age. Cox regression analyses were applied to estimate survival time, adjusting for gender, age, residence, insurance premium, Charlson comorbidity index, hospital admission days, and hospital admission times. An analysis including the number of antipsychotic prescriptions, a proxy indicator of adherence, into the fully adjusted model to reveal the effect of adherence on survival of patients served as a sensitivity analysis. Results: Subjects receiving SGAs had lower admission times and inpatient days, more antipsychotic prescriptions, and longer follow-up time than FGAs. Compared with the FGAs group, the adjusted hazard ratio of mortality was 0.58 (95% confidence interval =0.34-0.96, p=034) for SGAs group. After controlling for the number of antipsychotic prescriptions, the difference in mortality between antipsychotic generations was non-significant. Conclusions: The results of this study suggest that SGAs were better than FGAs in mortality among patients suffering schizophrenia. The difference in mortality can be explained by the better medication adherence of SGAs.