Clozapine as a first‐ or second‐line treatment in schizophrenia: a systematic review and meta‐analysis

OBJECTIVE: No consensus exists on whether clozapine should be prescribed in early stages of psychosis. This systematic review and meta‐analysis therefore focus on the use of clozapine as first‐line or second‐line treatment in non‐treatment‐resistant patients. METHODS: Articles were eligible if they investigated clozapine compared to another antipsychotic as a first‐ or second‐line treatment in non‐treatment‐resistant schizophrenia spectrum disorders (SCZ) patients and provided data on treatment response. We performed random‐effects meta‐analyses. RESULTS: Fifteen articles were eligible for the systematic review (N = 314 subjects on clozapine and N = 800 on other antipsychotics). Our meta‐analysis comparing clozapine to a miscellaneous group of antipsychotics revealed a significant benefit of clozapine (Hedges’ g = 0.220, P = 0.026, 95% CI = 0.026–0.414), with no evidence of heterogeneity. In addition, a sensitivity analysis revealed a significant benefit of clozapine over risperidone (Hedges’ g = 0.274, P = 0.030, 95% CI = 0.027–0.521). CONCLUSION: The few eligible trials on this topic suggest that clozapine may be more effective than other antipsychotics when used as first‐ or second‐line treatment. Only large clinical trials may comprehensively probe disease stage‐dependent superiority of clozapine and investigate overall tolerability.