Prior Antipsychotic Prescribing in Patients Currently Receiving Clozapine: A Case Note Review

Background: Clozapine is indicated for the treatment of resistant schizophrenia, which is usually defined as failure to respond to adequate trials of 2 antipsychotics. It is thought that only clozapine is likely to be effective in such cases and that other drugs are ineffective. We sought to discover prior patterns of antipsychotic prescribing in schizophrenic patients eventually prescribed clozapine.

Method: Prescribing histories were obtained from prescription charts and case notes for all inpatients prescribed clozapine in 4 hospitals in southeast London during April 2001.

Results: 120 patients were identified, of whom 112 had been diagnosed with schizophrenia or schizoaffective disorder and whose data were analyzed. The mean duration of illness was 15.1 years. Subjects had experienced a mean of 9.2 (range, 2-35) episodes of antipsychotic prescription before clozapine was first used, with 5.7 (range, 0-25) episodes constituting adequate trials (drug used at therapeutic dose for 6 weeks). The mean number of different antipsychotics used was 5.5 (range, 1-13), with a mean of 4.0 (range, 0-12) given an adequate trial. Ninety percent of patients (N=101) had received an atypical antipsychotic before first use of clozapine, and 65% (N=73) had previously received antipsychotic polypharmacy. The mean maximum theoretical delay in using clozapine was 5.0 years (range, 0-11.1 years). Longer delay was significantly (p < .05) associated with being aged over 30 years at the time of the study, being diagnosed with psychotic illness before the introduction of clozapine, and completing adequate trials of 2 different antipsychotics before the introduction of clozapine or risperidone.

Conclusion: Clozapine treatment was quite likely delayed for longer than is clinically desirable. This delay may have important effects on quality of life, clinical outcome, and health resource utilization.