Hematological Changes in Clozapine Users: A Study in a Brazilian Community Sample.

Introduction: Clozapine is the only antipsychotic with proven superior efficacy for treatment-resistant schizophrenia. However, global utilization rates remain suboptimal due to concerns about hematological side effects. This study aimed to investigate hematological abnormalities among clozapine users at a large community center in the Brazilian countryside.

Methods: This study adopts a real-world approach and was conducted based on a retrospectively analyzed complete blood counts from clozapine users in Goiás, Brazil. We describe the total number and percentage of participants presenting blood dyscrasias. Logistic regression models, using Stata v.18, were employed to evaluate whether sex or age were associated with the presentation of neutropenia.

Results: Data from 6,160 complete blood counts from 486 patients taken between 2011 and 2018 were analyzed. Blood dyscrasias were observed in 37.4% of patients, with anemia being the most common (23.6%), followed by thrombocytopenia (9.46%) and eosinophilia (13.7%). Neutropenia occurred in 4.52% of patients, primarily mild (3.9%) and moderate (0.62%), with no cases of agranulocytosis identified.

Discussion: Clozapine users showed a higher prevalence of blood dyscrasias compared to the overall Brazilian population. Most cases of neutropenia were mild and transient. Our results suggest a lower risk of severe neutropenia and emphasize the need to investigate other blood dyscrasias.