Prevalence of obsessive-compulsive symptoms in patients with schizophrenia treated with clozapine: a scoping review

Background: Schizophrenia is a complex psychiatric disorder, and in patients treated with clozapine, it may induce or exacerbate obsessive-compulsive symptoms (OCS), which negatively affect patients’ quality of life, functionality and treatment adherence. Despite its clinical relevance, the reported prevalence and characteristics of clozapine associated OCS vary widely, limiting effective management. Objective: This scoping review synthesizes evidence on the prevalence of OCS in patients with schizophrenia treated with clozapine and explores treatment characteristics (types, severity, dose, and time to onset/exacerbation). Methods: The PRISMA-ScR methodology guided the search in PubMed, LILACS, Embase, and Scielo. Observational studies in Spanish, English, Portuguese, and French reporting prevalence, incidence, or frequency of OCS in patients over 18 years with schizophrenia treated with clozapine were included. Clinical, qualitative studies, and those with access restrictions were excluded. Risk of bias was assessed using JBI tools. Results: Fourteen studies were included, reporting OCS prevalence between 20% and 76%, and de novo OCS between 4.8% and 46.4%. Clozapine dose ranged from 196 to 525 mg/day, and treatment duration from 5 to 210 months. The most common obsessions were aggression and checking, with severity ranging from mild to moderate. Conclusions: The prevalence of OCS in patients treated with clozapine varies widely. Further research is needed to clarify the relationship between dose, treatment duration, and the onset/exacerbation of OCS.