Clozapine and hematologic adverse reactions: Impact of the Risk Evaluation and Mitigation Strategy program

In October 2015, the Food and Drug Administration (FDA) instituted an update to the mandatory Risk Evaluation and Mitigation Strategy (REMS) program for clozapine to improve safety monitoring of hematologic events. However, the impact of the clozapine REMS program on reporting of hematologic adverse events has not been quantified.

We assessed adverse event reports for agranulocytosis, granulocytopenia, leukopenia, and neutropenia from the FDA Adverse Event Reporting System (FAERS) for a 1-year time period before (October 2014 to September 2015, pre-REMS) and after (October 2015 to September 2016, post-REMS) the implementation of the clozapine REMS program. The AERSMine platform was used to capture historical effect estimates (October 2004 to September 2014). Reporting odds ratios (ROR), proportional reporting ratios (PRR), and corresponding Taylor series 95% confidence intervals (CIs) were calculated for hematologic events with clozapine compared with all other medications using OpenEpi.

Reporting rates for agranulocytosis, granulocytopenia, leukopenia, and neutropenia with clozapine all increased from the pre-REMS to post-REMS time frames, ranging from a 2-fold increase with leukopenia to a 40-fold increase with neutropenia; the composite measure of all hematologic reports had a 12-fold increase. During the post-REMS time frame, the ROR increased by 1691% (111.4, 95% CI 100.6-123.4) compared with the pre-REMS time frame (7.1, 95% CI 5.2-9.6), and the PRR increased by 1280% (83.1, 95% CI 76.8-90.0 vs 6.9, 95% CI 5.1-9.4) for the composite outcome.

We observed significant increases in reports of hematologic adverse events with clozapine after the introduction of the clozapine REMS program. Future research should explore the impact of the less stringent exclusionary and discontinuation criteria on utilization (eg, expanded access) and clinical outcomes (eg, treatment effectiveness and adverse events).