ArticleSchizophrenia bulletin2025
Evaluating Reduced Blood Monitoring Frequency and the Detection of Hematological Abnormalities in Clozapine-Treated Patients With Schizophrenia: A Chart Review Study From the COVID-19 Pandemic.
Article in Schizophrenia bulletin, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
What it found
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Who cites it
2 citing papers in PubMed.
- A Call to Action for Starting Clozapine: Increasing Clozapine Use and Safety in a Post-REMS Era.Focus (American Psychiatric Publishing) · 2025Review
- The Safety of 12-Weekly Monitoring of Neutrophil Count in Long-Term Clozapine Patients.Acta psychiatrica Scandinavica · 2025Observational
Corrections and comments
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Authors and funding
5 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
background and hypothesisIn response to Health Canada's March 2020 directive, patients on clozapine for over 12 months were allowed to extend hematological testing intervals from 4 to 8 weeks during the COVID-19 pandemic. We hypothesized that this change would not affect the timely detection of hematological abnormalities in patients with severe mental illness. STUDY
designA chart review was conducted of patients at the Royal Ottawa who were prescribed clozapine from March 2019 to March 2021. We analyzed clinical and hematological data from electronic health records and Clozaril Support and Assistance Network database to compare occurrences of hematological abnormalities [leukopenia (white blood cell count <3.5 × 109/L) and agranulocytosis (absolute neutrophil count <0.5 × 109/L)] from March 17, 2020 to March 16, 2021, between standard and extended monitoring protocols using binomial logistic and zero-inflated negative binomial regressions. STUDY
resultsOf 621 patients, 196 were on extended blood monitoring, and 425 followed standard blood monitoring. Clozapine dose did not differ between groups (standard: 370 ± 201 mg; extended: 352 ± 172 mg; P = .14, ds = 0.10). Clozapine treatment duration up to March 2021 was 12.6 ± 8.3 years, with the extended group (10 ± 7.9 years) having a significantly (P < .01, ds = 0.50) shorter duration than the standard (14 ± 8.2 years). Extended monitoring did not significantly impact likelihood of detecting hematological abnormalities (OR = 0.83, 95% CI [0.58,1.41], P = .55) after controlling for age, sex, total bloodwork, and other psychotropics associated with neutrophil counts (ie, valproate, olanzapine). No patient on the extended regimen developed agranulocytosis.
conclusionsReducing blood monitoring frequency in patients on clozapine for more than 12 months did not compromise detection of hematological abnormalities.
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