ArticleSchizophrenia bulletin2026
Clozapine-Associated Neutropenia among People on Clozapine in Japan: A Nationally Representative Retrospective Cohort Study.
Article in Schizophrenia bulletin, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
1 citing paper in PubMed.
- Clozapine-induced inflammation: a case report.Frontiers in psychiatry · 2026Article
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Authors and funding
6 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
background and hypothesisClozapine is the most effective antipsychotic for treatment-resistant schizophrenia, but use is constrained by potentially life-threatening neutropenia and mandatory hematological monitoring. Evidence from Western cohorts suggests risk is concentrated early in treatment, yet data from Japan where monitoring is stringent, remain limited. STUDY
designRetrospective study including all patients prescribed clozapine from July 2009-January 2020 in Japan. Mild neutropenia was defined as absolute neutrophil count (ANC) 1.0-1.5 × 109/L, and serious neutropenia as ANC <1.0 × 109/L. Cumulative incidence of first mild and serious neutropenia was estimated using competing-risks methods. Associations with serious neutropenia were examined using Fine-Gray regression, including 2-week titration rate. STUDY
resultsThe cohort comprised 8263 individuals contributing 764 180 blood tests, with a median follow-up of 102 weeks. Overall, 3.0% patients experienced mild neutropenia and 2.2% had serious neutropenia. Among clozapine-naïve patients, cumulative incidence was 1.8% for mild and 1.6% for serious neutropenia at 18 weeks, rising to 3.1% and 2.5% at 104 weeks, respectively. Faster clozapine titration rate was associated with higher incidence of serious neutropenia (sub-distribution hazard ratio [sHR] 1.22, 95% CI, 1.02-1.45 per 50 mg dosage increase at 2-weeks), as was older age (sHR 1.05, 95% CI, 1.04-1.06), while prior clozapine exposure was associated with lower incidence (sHR 0.27, 95% CI, 0.09-0.86).
conclusionsIn Japan, neutropenia among clozapine-treated patients accrued predominantly within the first 1-2 years, with faster titration in the first 2-weeks being associated with a 22% increase in serious neutropenia risk per 50 mg. These findings support risk-stratified, less intensive monitoring approaches beyond the first 2 years.
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