The Impacts of Clozapine Use on the Risk and Outcomes of COVID-19 Disease in Patients with Schizophrenia.

Introduction: Clozapine may affect the outcome of severe COVID-19 infection due to its anti-inflammatory and immunosuppressant effects. This study aimed to investigate whether the risk of COVID-19 changed in schizophrenic patients using clozapine and to compare patients using clozapine with other antipsychotics in terms of COVID-19 severity. Methods: A total of 732 patients who were registered and followed up with a diagnosis of schizophrenia were included in the study. These patients' sociodemographic data, smoking status, medications, comorbidities, COVID-19 PCR results, and COVID-19 outcomes (inpatient care admission, intensive care unit admission, death) were retrospectively analyzed. Results: Of the 732 patients included in our study, 177 were using clozapine. Ninety-six of 732 patients were diagnosed with COVID-19, and 34 of these were being treated with clozapine. We found that clozapine use was an independent risk factor for COVID-19 positivity (OR=1.81 95% CI=1.13-2.90), inpatient care admission (OR=3.01, 95% CI=1.12-8.06). Conclusion: In our study, clozapine use was associated with an increased risk of COVID-19 positivity and inpatient care admission; however, it was not associated with ICU admission or death. Due to the frequent follow-up of patients using clozapine and the effects of clozapine on immunity, the frequency and/or identification of COVID-19 may be increased in these patients. Clozapine toxicity, granulocytopenia or agranulocytosis during the COVID-19 infection may have increased these patients' hospitalisation frequency.