To investigate the long-term real-world effectiveness of antipsychotics and other psychopharmacotherapies in the treatment of schizoaffective disorder (SCHAFF).


Two nationwide cohorts of SCHAFF patients were identified from Finnish and Swedish registers. Within-individual design was used with stratified Cox regression. The main exposure was use of antipsychotics. Adjunctive pharmacotherapies included mood stabilizers, antidepressants, and benzodiazepines and benzodiazepine-related drugs. The main outcome was hospitalization due to psychosis.


The Finnish cohort included 7655 and the Swedish cohort 7525 patients. Median follow-up time was 11.2 years (IQR 5.6–11.5) in the Finnish and 7.6 years (IQR 3.8–10.3) in the Swedish cohort. Clozapine and long-acting injectable (LAI) antipsychotics were consistently associated with a decreased risk of psychosis hospitalization and treatment failure (psychiatric hospitalization, any change in medication, death) in both cohorts. Quetiapine was not associated with a decreased risk of psychosis hospitalization. Mood stabilizers used in combination with antipsychotics were associated with a decreased risk of psychosis hospitalization (Finnish cohort HR 0.76, 95% CI 0.71–0.81; Swedish cohort HR 0.84, 0.78–0.90) when compared with antipsychotic monotherapy. Combination of antidepressants and antipsychotics was associated with a decreased risk of psychosis hospitalization in the Swedish cohort (HR 0.90, 0.83–0.97) but not in the Finnish cohort (1.00, 0.94–1.07), and benzodiazepine use was associated with an increased risk (Finnish cohort HR 1.07, 1.01–1.14; Swedish cohort 1.21, 1.13–1.30).


Clozapine, LAIs, and combination therapy with mood stabilizers were associated with the best outcome and use of quetiapine and benzodiazepines with the worst outcome in the treatment of SCHAFF.

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