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Smoking Cessation Drug Varenicline Does Not Increase Psychiatric Risk
A new analysis of the Evaluating Adverse Events in a Global Smoking Cessation Study (EAGLES) found moderate to strong evidence that the smoking cessation drug varenicline does not increase the risk of neuropsychiatric adverse events in people without pre-existing psychiatric conditions. The study, which used Bayesian analysis, was published online ahead of print in Addiction.
“The shadow of psychiatric problems has arguably cost thousands of lives by putting people off using varenicline to help them stop [smoking], and doctors off prescribing it,” said lead author Emma Beard, PhD, of University College London in the United Kingdom. “This analysis should provide further reassurance to smokers and clinicians that this is a safe, life-saving drug.”
Results from EAGLES, a randomized controlled trial that looked at neuropsychiatric adverse events attributable to varenicline, bupropion, the nicotine patch, and placebo in 4116 smokers with psychiatric disorders and 4028 smokers without psychiatric disorders, were originally published in 2016. Using classical frequentist hypothesis testing with alpha set to 0.05, researchers at the time did not find adequate evidence to reject the hypothesis that there was no difference in psychiatric adverse events across the treatments.
“This might be because the null hypothesis was true or because the data were insensitive,” wrote Dr. Beard and colleagues in the latest analysis. “The present study aimed to test the hypothesis more directly using Bayes factors.”
According to findings from the secondary analysis, evidence was moderate to strong that varenicline did not increase the risk of psychiatric adverse events relative to placebo in people without a history of psychiatric disorders.
In people with preexisting psychiatric disorders, evidence also pointed to no increased risk, although with less certainty, researchers reported. However, there was very strong evidence that varenicline did not increase the risk of severe psychiatric adverse events in the population.
“In my view, this kind of Bayesian analysis should be standard for assessing all drug side effects, including for example COVID-19 vaccines,” said senior author Robert West, University College London. “It directly answers the question we want answered: what is the strength of evidence that the drug has side effects? I’d like to see all studies of side effects use this approach in future.”
—Jolynn Tumolo
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