Clozapine Treatment and Risk of COVID-19

Abstract

Background: COVID-19 is a novel infection that leads to pneumonia in severe cases. Clozapine, an antipsychotic with unique efficacy in treatment resistant psychosis, is known to be associated with increasing risk of pneumonia. Aims: To investigate possible associations between clozapine treatment and increased risk of COVID-19 in patients with schizophrenia-spectrum disorders who are receiving antipsychotic medications, using electronic health records data, in a geographically defined population in London. Method: We identified 6304 individuals who had an ICD-10 diagnosis of schizophrenia-spectrum disorders and were taking antipsychotic during the 3 months prior the follow-up period. People who were on clozapine treatment were designated as the exposed group. Those on any type or combination of antipsychotic treatment that did not include clozapine were designated unexposed. We tested associations between clozapine treatment and COVID-19, adjusting for potential confounders. Results: 70 patients developed COVID-19. Individuals who were on clozapine had a nearly threefold increased risk of COVID-19 compared with those who were on other antipsychotic medication (hazard ratio HR=2.70, 95% CI 1.62 - 4.51). This association was attenuated but remained after adjustment for potential confounders. Conclusion: These findings provide support for the hypothesis that clozapine treatment is associated with increased risk of COVID-19. Further research will be needed in other samples to confirm this association. Potential clinical implications are discussed. Funding Statement: This work was supported by the Clinical Records Interactive Search (CRIS) system funded and developed by the National Institute for Health Research (NIHR) Mental Health Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London and a joint infrastructure grant from Guy’s and St Thomas’ Charity and the Maudsley Charity (grant number BRC-2011-10035). RDH DF and JHM receive salary support from the National Institute for Health Research (NIHR) Maudsley Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London. Declaration of Interests: RDH, received research funding from Roche, Pfizer, Janssen and Lundbeck, DF has received research funding from Janssen and Lundbeck. JHM has received research funding from Lundbeck. All other authors have no conflict of interest. Ethics Approval Statement: The research was conducted under ethical approval reference 18/SC/0372 from Oxfordshire Research Ethics Committee C.