Baseline neutrophil count, benign ethnic neutropenia risk, and clozapine haematological monitoring: A multi-ethnic retrospective cohort study from the United Arab Emirates.

Authors

Syed Ali Bokhari, Muhanad Elnoor, Mohamed Sabri, Mohammed Bardi, Faisal A Nawaz, Syed Fahad Javaid

Published in

Schizophrenia research. Volume 297. Pages 76-88. Aug 03, 2026. Epub Aug 03, 2026.

Abstract

Concerns about haematological toxicity and absolute neutrophil count (ANC) monitoring may limit clozapine use, particularly in multi-ethnic populations where benign ethnic neutropenia (BEN) and lower baseline ANC are common. We characterised baseline ANC distribution, nationality-derived BEN-risk, post-initiation ANC outcomes, and haematological monitoring patterns in a multi-ethnic United Arab Emirates clozapine cohort.
We conducted a retrospective cohort study at a tertiary psychiatric hospital in the United Arab Emirates. Adults with documented clozapine administration and at least one post-initiation ANC between 1 January 2018 and 31 July 2024 were included. Nationality-derived BEN-risk, baseline ANC, post-initiation ANC outcomes within a five-band hierarchy, monitoring intensity, and pre-specified sensitivity and exploratory analyses were examined.
Among 239 patients, 179 formed the final study cohort, contributing 284.7 on-clozapine person-years. Overall, 158 patients (88.3%) had no post-initiation ANC <2.0 × 10⁹/L, 16 (8.9%) entered the 1.5-2.0 × 10⁹/L low-ANC monitoring range, 2 (1.1%) reached conventional-threshold neutropenia, 3 (1.7%) reached severe neutropenia, and none reached agranulocytosis range. Five patients (2.8%) met the clinically meaningful ANC <1.5 × 10⁹/L threshold; all were BEN-risk, all had concomitant valproate exposure, and four had concomitant lithium exposure. Baseline ANC was lower in BEN-risk patients and statistically accounted for much of the BEN-risk-to-outcome association in an exploratory analysis.
Low ANC during clozapine treatment was uncommon and strongly shaped by baseline ANC and BEN-risk context. Baseline ANC-informed and BEN-aware interpretation may reduce unnecessary treatment interruption while preserving haematological safety. BEN-risk was inferred from nationality, not confirmed genetically; all five low-ANC cases received concomitant valproate; associations are observational.

PMID:
42546354
Bibliographic data and abstract were imported from PubMed on 04 Aug 2026.

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