Reduction in Absolute Neutrophil Counts in Patient on Clozapine Infected with COVID-19

Abstract

Despite its severe adverse effects, such as agranulocytosis, clozapine is the primary treatment for treatment-resistant schizophrenia. The established clozapine monitoring system has contributed to reducing agranulocytosis incidence and mortality rates. However, the pandemic coronavirus disease 2019 (COVID-19) has caused changes in the monitoring system. This review aimed to assess the current evidence on the neutrophil changes in the patient on clozapine treatment and infected with COVID-19. Individual cases reported various absolute neutrophil count (ANC) levels, normal, reduced, or elevated. No agranulocytosis case was reported. One case had a borderline moderate-severe ANC level, but the patient was in the 18-week period of clozapine treatment. A cumulative analysis of case the series initially reported inconclusive results. However, a more recent study with a larger sample size reported a significant reduction in the ANC during COVID-19 infection. Nevertheless, this effect is transient as no significant difference was found between the baseline and the post-infection period in ANC levels. In conclusion, COVID-19 is associated with a temporary reduction in ANC levels. The results supported the recommendation to reduce the frequency of clozapine monitoring in the eligible candidates. However, more data are required to confirm the current findings given the limitations, including study design, sample size, and statistical analysis.

Neutropenia in Patients With Clozapine-Treated Schizophrenia: An Effect of Clozapine or a Consequence of SARS-CoV-2 Infection? A Systematic Review

“…Blood cell count and clozapine plasma concentration should be measured before and after the vaccination. 40…”

Change in absolute neutrophil count after COVID-19 infection in patients using clozapine versus other antipsychotics

“…Previously, Gee and Taylor (2021) demonstrated that COVID-19 infection leads to a temporary ANC reduction in patients treated with clozapine. Subsequent case reports corroborated this finding (Bonaccorso et al ., 2021; Hata et al ., 2021; Ramli et al ., 2021; Moga et al ., 2022b). Nevertheless, as there were no comparison groups in these studies, it was difficult to ascertain whether the changes were non-specific findings in patients with SMIs (De Hert et al ., 2021) or the outcome of a unique interaction of clozapine with COVID-19.…”

“…However, an unexpected drop in the neutrophil count is frequently observed in clozapine-treated COVID-19 patients (Gee and Taylor, 2020, 2021). Clinicians worry that this response signifies a decompensating hematological system (Bonaccorso et al ., 2021; Ramli et al ., 2021; Moga et al ., 2022b).…”

First onset of persistent neutropenia in patient undergoing long-term clozapine treatment after vaccination against COVID-19 and SARS-CoV-2 infection in short interval – a case report

“…Sama dawka nie wpływała na ryzyko ciężkiej neutropenii [27,28]. Innym czynnikiem ryzyka był krótki czas leczenia, ponieważ spadek ANC był większy u pacjentów na początku leczenia [29] niż u pacjentów długotrwale stosujących klozapinę. Jednakże odnotowano również pewne wyjątki -jeden przypadek ciężkiej agranulocytozy wystąpił u pacjenta, który rozpoczął leczenie klozapiną w 2007 roku [30].…”