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.