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Cardiac arrest and ventricular arrhythmia in patients taking antipsychotic drugs: cohort study using administrative
Sean Hennessy1, Warren B Bilker, Jill S Knauss
1Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. shenness@cceb.med.upenn.edu
Insights
Patients with treated schizophrenia face higher risks of cardiac arrest and ventricular arrhythmia compared to controls. While thioridazine generally showed no increased risk, high doses may elevate cardiac events.
Area of Science:
- Cardiology
- Psychiatry
- Pharmacology
Background:
- Schizophrenia treatment is associated with potential cardiovascular risks.
- Understanding these risks is crucial for patient safety and effective treatment.
Purpose of the Study:
- To compare cardiac arrest and ventricular arrhythmia rates in treated schizophrenia patients versus controls.
- To evaluate the cardiac risks associated with specific antipsychotic medications, including thioridazine.
Main Methods:
- A cohort study utilizing administrative data from 3 US Medicaid programs.
- Inclusion of patients with treated schizophrenia (on clozapine, haloperidol, risperidone, or thioridazine) and control groups (glaucoma, psoriasis).
- Primary outcome measure was the diagnosis of cardiac arrest or ventricular arrhythmia.
Main Results:
- Patients with treated schizophrenia exhibited significantly higher rates of cardiac arrest and ventricular arrhythmia (rate ratios 1.7-3.2).
- Overall, thioridazine did not increase risk compared to haloperidol (rate ratio 0.9).
- However, thioridazine at doses ≥600 mg was linked to increased events (rate ratio 2.6) with a dose-response relationship (P=0.038).
Conclusions:
- The elevated cardiac risk in treated schizophrenia patients may stem from the disease itself or its pharmacotherapy.
- Thioridazine's overall cardiac risk was comparable to haloperidol, but high doses warrant caution.
- Prescribing thioridazine at the lowest effective dose is recommended to mitigate potential cardiac risks.
Objective:
To examine the rates of cardiac arrest and ventricular arrhythmia in patients with treated schizophrenia and in non-schizophrenic controls.
Design:
Cohort study of outpatients using administrative data.
Setting:
3 US Medicaid programmes.
Participants:
Patients with schizophrenia treated with clozapine, haloperidol, risperidone, or thioridazine; a control group of patients with glaucoma; and a control group of patients with psoriasis.
Main Outcome Measure:
Diagnosis of cardiac arrest or ventricular arrhythmia.
Results:
Patients with treated schizophrenia had higher rates of cardiac arrest and ventricular arrhythmia than controls, with rate ratios ranging from 1.7 to 3.2. Overall, thioridazine was not associated with an increased risk compared with haloperidol (rate ratio 0.9, 95% confidence interval 0.7 to 1.2). However, thioridazine showed an increased risk of events at doses > or =600 mg (2.6, 1.0 to 6.6; P=0.049) and a linear dose-response relation (P=0.038).
Conclusions:
The increased risk of cardiac arrest and ventricular arrhythmia in patients with treated schizophrenia could be due to the disease or its treatment. Overall, the risk with thioridazine was no worse than that with haloperidol. Thioridazine may, however, have a higher risk at high doses, although this finding could be due to chance. To reduce cardiac risk, thioridazine should be prescribed at the lowest dose needed to obtain an optimal therapeutic effect.