Effectiveness of clozapine use in delaying hospitalization in routine clinical practice: a 2 year observational study

Previous naturalistic observational studies have produced mixed results concerning the effectiveness of clozapine on hospitalization, partly because the decision to place a patient on clozapine versus another antipsychotic has been confounded with the known efficacy of clozapine over other antipsychotics.

To examine the effectiveness of clozapine compared to other antipsychotic drugs in delaying hospitalization in routine clinical practice.

Consecutive patients with schizophrenia or schizoaffective disorders registered to start on clozapine in one English mental health service over a six-year period were followed up for 2 years from the time of discharge (index admission). Time to hospitalization was used to compare patients started and discharged on clozapine (CG = 126) and those registered to start on clozapine but subsequently discharged on other antipsychotics (OAG = 34) using Kaplan-Meier survival analysis.

There were more hospitalizations with OAG 13 [38%] than CG = 27 [21%]. Time to hospitalization (25th centile) was 299 days in CG and 136 days in OAG among patients who were successfully discharged from hospital (x2 = 4.80, df = 1, p = 0.043). The time to hospitalization was delayed in CG versus other OAG when baseline differences in age, gender, marital status, previous forensic mental health service, case management and site of initiation were controlled [odds ratio (95% confidence intervals) = 1.87 (1.01, 4.33), p = 0.048].

Clozapine delays hospitalization in patients with treatment resistant schizophrenia if they are started on clozapine in the community or successfully discharged from hospital following their index admission.