Transient drop in the neutrophil count during COVID-19 regardless of clozapine treatment in patients with mental illness

Vallecillo, Gabriel; Marti-Bonany, Josep; José Robles, Maria; Fortuny, Joan Ramón; Lana, Fernando; Pérez, Victor

Background: Some case series have reported severe neutropenia in patients on clozapine treatment resulting inwithdrawal and raising the concern of clozapine toxicity in the setting of COVID-19. The aims of the study was to compare the neutrophil dynamics between patients with mental illness according to the clozapine treatment. Methods: This observational study included patients with COVID-19 admitted in a psychiatric center from March 2020 to March 2021. Median change of neutrophil count between baseline and the first week of infection was the main outcome. Results: a total of 31 patients were included and 16(51.6%) were on clozapine treatment. Median change of neutrophil count at COVID-19 was -560 cells/ mcL (IQR:-1510,-1160). There was not differences in median neutrophil change according to clozapine treatment: -680(IQR:-1502,-145) cells/mcL vs. -550(IQR:-1805,-405) cells/mcL for the non-clozapine group (p 0.51). After COVID-19 neutrophil counts returned to baseline levels. Neutropenia was observed in 3(9.6%) patients and related to the introduction of medications for the COVID-19 treatment.Median clozapine plasma concentrations increased during COVID-19: 450 (IQR:370-490) ng/mL at baseline vs. 604(400-870) ng/mL at CoVID-19(p 0.04). Five patients had clozapine levels> 600 ng/mL requiring dose reduction. Limitations: the observational design and the small number of patients included. Conclusion: a comprehensive clinical assessment of suspected COVID-19 infection in patients with mental illness, including evaluation for features of pneumonia, full blood count and risk of side effects of newly introduced treatments is essential. In addition, clozapine treatment should be continued, however, consideration should be given to dose reduction.