Substantial delays to clozapine initiation remain and antipsychotic polypharmacy and high doses are commonly used prior to clozapine, despite treatment guidelines.

Professionals identified the dominant barriers to prescribing as being patient focussed - refusal of blood test monitoring or concerns about tolerability. Clinician fears about compliance or medical complications were also important. The development of out-patient services specifically tasked with initiating clozapine may help to increase the frequency of prescribing of clozapine earlier in treatment than is currently seen.

Augmentation with a second antipsychotic is modestly beneficial in patients not responding fully to clozapine. Tolerability seems not to be adversely affected, at least in the short term. Longer studies do not appear to increase the probability of showing positive effects for augmentation.