Although clozapine is often discontinued, there is a paucity of guidelines and evidence on treatment options after clozapine discontinuation. Moreover, it is currently unknown whether reinstating clozapine in patients formerly using clozapine should be avoided.

To compare the real-world effectiveness of antipsychotics after clozapine cessation.

From Finnish registry data (1995–2017), we identified 2250 patients with schizophrenia who had been using clozapine for ≥1 year before treatment cessation. The primary analysis consisted of adjusted within-individual analyses of psychiatric ward readmission owing to psychosis and treatment failure. Secondary analyses concerned between-individual mortality differences.

Compared with no use of antipsychotics, risk of psychiatric ward readmission was lowest for reinitiation of clozapine (adjusted hazard ratio (aHR) 0.49; 95% CI 0.40–0.61; P < 0.0001), oral olanzapine (aHR 0.58; 95% CI 0.48–0.71; P < 0.0001) and antipsychotic polypharmacy (aHR 0.62; 95% CI 0.53–0.72; P < 0.0001). Risk of treatment failure was lowest for aripiprazole long acting injectable (aHR 0.42; 95% CI 0.27–0.65; P < 0.0001), reinitiation of clozapine (aHR 0.49; 95% CI 0.43–0.57; P < 0.0001) and oral olanzapine (aHR 0.69; 95% CI 0.61–0.77; P < 0.0001). Mortality risk was lowest for reinitiation of clozapine (aHR 0.18; 95% CI 0.09–0.36; P < 0.0001) and oral olanzapine (aHR 0.26; 95% CI 0.17–0.40; P < 0.0001).

Clozapine and olanzapine are the most effective and safest treatment options in those discontinuing clozapine for undefined reasons. Clozapine should therefore be reconsidered in patients with schizophrenia who previously discontinued this compound.