A case report on the effects of COVID-19 on ANC monitoring in a patient on long-term clozapine treatment.

BACKGROUND

Clozapine carries a US boxed warning for severe neutropenia, and strict monitoring is required through the FDA's Risk Evaluation and Mitigation Strategy (REMS) program. Patients with confirmed diagnosis of COVID-19 are also at risk for neutropenia. For patients on clozapine, the diagnosis of this novel virus may require an increase in the frequency of scheduled ANC monitoring. A case report of moderate neutropenia following COVID-19 diagnosis that required an increase in the frequency of ANC monitoring in a patient on long-term clozapine treatment is discussed.

CASE REPORT

A 33-year-old white man with schizophrenia had been on clozapine for more than 2 years, with an ANC monitoring schedule once every 4 weeks. The patient was admitted to the hospital for worsening aggressive behavior. On day 11 of hospital admission, he tested positive for COVID-19. Five days following this diagnosis, the patient's ANC dropped from 2.2/L to 0.8/L. This decrease led to daily ANC labs and the clozapine regimen being held for 1 day. Throughout the patient's admission adjustments were made to the frequency of lab monitoring based on fluctuations in his ANC levels.

DISCUSSION

There have been limited case reports on patients receiving clozapine experiencing neutropenia following the diagnosis of COVID-19. To the authors knowledge, this is the first case report from the United States that specifically discusses the required changes to ANC monitoring.

CONCLUSIONS

Patients on clozapine who test positive for COVID-19 may be at an even greater risk for neutropenia, compared with clozapine patients without COVID-19. Increasing the frequency of ANC monitoring should be considered in the weeks following the diagnosis to ensure that clozapine treatment can be safely adjusted, or even discontinued.