Clozapine and long-acting injectable antipsychotic medications were the pharmacologic treatments with the highest rates of prevention of relapse in schizophrenia. The risk of rehospitalization is about 20% to 30% lower during long-acting injectable treatments compared with equivalent oral formulations.

Key Points Question Are there specific antipsychotic combinations that are superior to monotherapies in the maintenance treatment of schizophrenia? Findings This cohort study on 62 250 individuals with schizophrenia with up to 20-year follow-up used within-individual analysis to minimize selection bias and showed that antipsychotic polypharmacy in general was associated with slightly lower risk of psychiatric rehospitalization than monotherapy. Clozapine plus aripiprazole combination was associated with the best outcome, having 14% to 23% lower risk of rehospitalization than clozapine alone, which was the monotherapy associated with the best outcomes. Meaning The findings of this study suggest that certain types of polypharmacy may be associated with fewer rehospitalizations than monotherapies.

Antipsychotics are effective in preventing relapses of schizophrenia, but it is generally believed that their long‐term use is harmful for patients’ physical well‐being. However, there are no long‐term studies which have verified this view. This nationwide, register‐based cohort study aimed to assess the risk of hospitalization due to physical health problems, as a marker for severe physical morbidity, and the risk of all‐cause mortality, as well as of cardiovascular and suicidal death, associated with antipsychotic use in all patients treated for schizophrenia in inpatient care between 1972 and 2014 in Finland (N=62,250), with up to 20 years of follow‐up (median: 14.1 years). The use of antipsychotic drugs (i.e., use of any antipsychotic compared with non‐use) and the use of specific antipsychotics were investigated, and outcomes were somatic and cardiovascular hospitalization, and all‐cause, cardiovascular and suicide death. Hospitalization‐based outcomes were analyzed by a within‐individual design to eliminate selection bias, comparing use and non‐use periods in the same individual by stratified Cox model. Mortality outcomes were assessed by traditional between‐individual Cox multivariate models. The adjusted hazard ratios (aHRs) for any somatic hospitalization and cardiovascular hospitalization were 1.00 (95% CI: 0.98‐1.03) and 1.00 (95% CI: 0.92‐1.07) during use of any antipsychotic compared to non‐exposure periods within the same individual. The aHRs were 0.48 (95% CI: 0.46‐0.51) for all‐cause mortality, 0.62 (95% CI: 0.57‐0.67) for cardiovascular mortality, and 0.52 (95% CI: 0.43‐0.62) for suicide mortality during use vs. non‐use of any antipsychotic. The most beneficial mortality outcome was associated with use of clozapine in terms of all‐cause (aHR=0.39, 95% CI: 0.36‐0.43), cardiovascular (aHR=0.55, 95% CI: 0.47‐0.64) and suicide mortality (aHR=0.21, 95% CI: 0.15‐0.29). The cumulative mortality rates during maximum follow‐up of 20 years were 46.2% for no antipsychotic use, 25.7% for any antipsychotic use, and 15.6% for clozapine use. These data suggest that long‐term antipsychotic use does not increase severe physical morbidity leading to hospitalization, and is associated with substantially decreased mortality, especially among patients treated with clozapine.

Among patients with schizophrenia, LAI use is associated with an approximately 30% lower risk of death compared with oral agents. SG LAIs and oral aripiprazole are associated with the lowest mortality.

Very little is known about the comparative long-term effectiveness of novel antipsychotics in relapse prevention, especially in first-episode schizophrenia. Nationwide data from Finnish health care registers were gathered prospectively for all persons with periods of inpatient care due to schizophrenia in Finland during 1972–2014. Altogether 62250 persons were included in the prevalent cohort, and 8719 in the incident (first-episode schizophrenia) cohort. The follow-up for antipsychotic use started at 1996 for the prevalent cohort, and at the first discharge from inpatient care for the incident cases. Within-individual Cox regression models for risk of psychiatric and all-cause hospitalization were constructed to compare risk during antipsychotic use and no use using individual as his/her own control to eliminate selection bias. With follow-up time up to 20 years (median = 14.1, interquartile range = 6.9–20.0), 59% of the prevalent cohort were readmitted to psychiatric inpatient care. Olanzapine long-acting injection (LAI; adjusted hazard ratio = 0.46, 95% confidence interval = 0.36–0.61), clozapine (0.51, 0.49–0.53), and paliperidone LAI (0.51, 0.40–0.66) were associated with the lowest risk of psychiatric rehospitalization in the prevalent cohort. Among first-episode patients, the lowest risks were observed for flupentixol LAI (0.24, 0.12–0.49), olanzapine LAI (0.26, 0.16–0.44), and perphenazine LAI (0.39, 0.31–0.50). Clozapine and LAIs were associated with the lowest risk of all-cause hospitalization in both cohorts. Clozapine and LAIs are the most effective treatments in preventing psychiatric and all-cause hospitalization among chronic and first-episode patients with schizophrenia.