Clozapine and Neutropenia in Patients with Schizophrenia and SARS-CoV-2 Infection

Background: Clozapine (CLZ) is used for treatment-resistant schizophrenia (TRS). Adverse reactions to clozapine include neutropenia. In March 2020, WHO declared the COVID-19 pandemic and after, psychiatrists raised concerns regarding continuation of clozapine, due to multiple restrictions. We aimed to provide a study on the association between neutropenia and clozapine in patients with schizophrenia and COVID-19. Aim: To assess the neutrophil count in patients with schizophrenia treated with clozapine and infected with COVID-19. Methods: The study patients with schizophrenia, according to DSM-5, admitted to the Clinical Hospital of Psychiatry and Neurology Brasov, Romania, between April 2020 and October 2021. The inclusion criteria included positive RT-PCR (real-time PCR) test for COVID-19 and treatment with clozapine. We assessed three values of ANC (absolute neutrophil count): before COVID-19 infection (last ANC obtained at mandatory check), during infection and 1 month after resolution (first negative PCR test). Results: Of the 105 cases, 95 did not have neutropenia. Fifty-nine patients were males (62.1%), mean age was 43.5 years (SD = 12.1) with an average of clozapine treatment of 52.4 months (SD = 11.9). At baseline, they had a small reduction in the ANC mean value (4.41 x 109/1; SD = 2.22) which did not constitute a statistically significant decline from the prior to COVID-19 mean value of 4.66 x 109/1 (SD = 2.34; p = 0.45). Values were also normal in the first month after negative PCR testing (4.45 x 109/1; SD = 2.35; p = 0.91). A total of 10 patients (9.5%) had neutropenia. The age, dose of clozapine and duration of treatment were not statistically different compared to the group without neutropenia. Conclusion: Psychiatrists and other health professionals should keep in mind that neutrophil count may decrease during COVID-19 infection in patients taking clozapine and in some cases, neutropenia may even occur. We assumed that neutropenia could be caused by COVID-19 and clozapine interaction.

Automated summary

This study aimed to assess the neutrophil count in patients with schizophrenia treated with clozapine and infected with COVID-19. The results showed that the majority of patients did not experience a significant decline in neutrophil count before COVID-19 infection and one month after resolution. However, a small percentage of patients exhibited neutropenia. The study suggests that neutropenia may be a result of the interaction between COVID-19 and clozapine.