New research published in Schizophrenia Bulletin has reported that oral clozapine and olanzapine long-acting injection (LAI) emerged as the most effective treatments for preventing hospitalization among patients with chronic and first-episode schizophrenia in a large, long-term comparative effectiveness study.

As part of their ongoing work in this area, the researchers investigated the risk of all-cause and psychiatric hospitalization associated with novel antipsychotic drugs in a national Finnish registry of individuals with schizophrenia.  A total of 62,250 people were included in the prevalent cohort and 8,719 in the incident cohort. Follow-up for antipsychotic use started for the prevalent cohort and at the first discharge from inpatient care for the incident cases.

To eliminate selection bias, risk models for psychiatric and all-cause hospitalization were constructed to compare risk during antipsychotic use and no use. Around 59% of people in the prevalent cohort were readmitted to psychiatric hospitals during a median 20 years of follow-up. Overall, LAI use was associated with lower risk of psychiatric rehospitalization, especially among the incident cohort, which also had a lower risk with LAIs compared to oral antipsychotics.

In the prevalent cohort, differences between the two classes of drugs were less pronounced. With respect to specific antipsychotics used in monotherapy in the prevalent cohort, olanzapine LAI, oral clozapine, and paliperidone LAI were associated with the lowest risk of psychiatric rehospitalization compared to no antipsychotic use, with adjusted hazard ratios of 0.46, 0.51 and 0.51, respectively.

Among first-episode patients, the lowest risks were observed for flupentixol LAI, olanzapine LAI, and perphenazine LAI – with aHRs of 0.24, 0.26 and 0.39, respectively. The authors report that the same antipsychotics were associated with the lowest psychiatric rehospitalization risks when compared to oral olanzapine and to no use of antipsychotics.

LAIs were associated with a lower risk of psychiatric and all-cause hospitalization than oral antipsychotics. This was seen both in the prevalent and the incident cohorts. Of specific antipsychotics, olanzapine LAI and clozapine were associated with the lowest risk of hospitalization in all analyses.

The results of the study can be used to tier formularies and structure therapeutic algorithms to enhance the cost effectiveness of mental health care. This report is a valuable contribution to our knowledge of the effectiveness of antipsychotic drugs in the treatment of schizophrenia, the researchers concluded.