Related Experiment Video

Updated: Jul 12, 2026

Handwriting Analysis Indicates Spontaneous Dyskinesias in Neuroleptic Naïve Adolescents at High Risk for Psychosis
05:52

Handwriting Analysis Indicates Spontaneous Dyskinesias in Neuroleptic Naïve Adolescents at High Risk for Psychosis

Published on: November 21, 2013

Prevalence and frequency of haematological testing in patients initiating clozapine in the USA

Katsiaryna Bykov1, Mufaddal Mahesri2, Krista F Huybrechts2

  • 1Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA kbykov@bwh.harvard.edu.

BMJ Mental Health
|July 10, 2026
PubMed

Insights

Hematological testing for clozapine initiation was underutilized before treatment and in the first six months. Testing rates improved after six months, aligning with recommendations.

Area of Science:

  • Pharmacovigilance
  • Clinical Pharmacy
  • Health Services Research

Background:

  • Clozapine initiation in the USA previously mandated the Clozapine Risk Evaluation and Mitigation Strategy (REMS) for haematological testing.
  • Despite REMS elimination in June 2025, clinical guidelines for clozapine testing persist.
  • Adherence to clozapine testing protocols in real-world practice remains under-examined.

Purpose of the Study:

  • To determine the prevalence and frequency of haematological testing in patients prescribed clozapine.
  • To evaluate testing rates before clozapine initiation and during the initial 24 months of therapy.

Main Methods:

  • A retrospective cohort study analyzed data from three US health insurance claims databases (2000-2022).
  • Assessed the proportion of patients with pre-initiation testing (within 60 days) and testing frequency (tests per 30 days) during the first 24 months of clozapine treatment.
  • Identified tests using billing codes; assumed hospitalized patients received testing.

Main Results:

  • Out of 62,003 clozapine initiations, 71% had pre-initiation testing.
  • Mean testing rates were 2.2 tests/30 days (months 0-6), 2.0 tests/30 days (months 7-12), and 1.5 tests/30 days (months 13-24).
  • Testing rates were lower than expected before initiation and during the first six months of therapy.

Conclusions:

  • Haematological testing adherence before clozapine initiation and in early treatment phases was suboptimal.
  • Testing frequency met recommendations in later treatment stages (after 6 months).
  • Further investigation is needed to understand the reasons for underutilization of recommended clozapine testing, particularly in the initial treatment period.
Abstract

Keywords:
PsychotherapySchizophrenia

Related Concept Videos

Psychosis: Goals of Pharmacotherapy01:26

Psychosis: Goals of Pharmacotherapy

Antipsychotic drugs are a crucial treatment method for acute and chronic psychoses, bipolar illness, and behavioral disorders. The selection of these drugs depends on several factors, including the state of the disease, clinical judgment, possible drug interactions, and the patient's sensitivity to adverse effects. In immediate scenarios, such as delirium and dementia, short-term treatment with low doses of high-potency typical or atypical agents can effectively manage symptom exacerbation. For...
Psychosis and Antipsychotic Drugs: Overview01:28

Psychosis and Antipsychotic Drugs: Overview

The term "psychosis" refers to a spectrum of mental disorders characterized by abnormal thoughts, perceptions, and behaviors. It can manifest as mood disorders, dementia, delirium with psychotic features, substance-induced psychosis with psychotic features, brief psychotic disorder, delusional disorder, schizoaffective disorder, and schizophrenia. Among all these disorders, schizophrenia is the most common psychotic disorder, affecting 1% of the worldwide population. Psychotic symptoms in all...
Prevalence and Incidence01:08

Prevalence and Incidence

In statistical epidemiology and health sciences, two essential metrics—prevalence and incidence—are fundamental for understanding disease dynamics within a population. These measures enable public health officials, epidemiologists, and researchers to assess the burden of diseases, allocate resources effectively, and design impactful public health policies and interventions.
Prevalence indicates the proportion of individuals in a population who have a specific disease or health condition at a...
Drug Therapy01:28

Drug Therapy

The advent of drug therapy has profoundly shaped modern mental health care, providing targeted treatments for a range of psychological disorders. Psychotherapeutic drugs, classified into antianxiety, antidepressant, and antipsychotic medications, address symptoms across anxiety disorders, mood disorders, and schizophrenia. While these medications have transformed patient outcomes, they require careful management due to their potential side effects and limitations.
Antianxiety Medications