Patients taking Chantix had a heightened risk for hospitalizations and ED visits due to adverse cardiovascular events, according to findings published in the American Journal of Respiratory and Critical Care Medicine.
“[Chantix (varenicline, Pfizer)] has been shown to improve smoking cessation rates more effectively than bupropion, single forms of nicotine replacement, nonpharmacological methods and placebo in randomized clinical trials, but evidence regarding its real world cardiovascular and neuropsychiatric safety has been inconsistent,” Andrea Gershon MD, MSc, FRCP, associate professor of medicine, University of Toronto, told Healio Internal Medicine.
Gershon and colleagues performed a population-based, self-controlled risk interval study to assess the association between varenicline and risk for cardiovascular and neuropsychiatric events among a diverse, multicultural population.
The researchers identified 56,851 new users of varenicline from a Canadian-based cohort between Sept. 1, 2011, and Feb. 15, 2014. The users were observed for 1 year before starting varenicline and 1 year after starting varenicline. Researchers compared the relative incidences of cardiovascular and neuropsychiatric hospitalizations and ED visits in the 12-week treatment period of varenicline and the remaining observation period.
Data indicated that from year before to year following varenicline receipt, there were 6,317 cardiovascular and 10,041 neuropsychiatric hospitalizations and ED visits.
Cardiovascular events, including heart attack, stroke, arrhythmias, unstable angina and peripheral vascular disease, occurred 34% more often during the risk interval than the control interval (relative incidence = 1.34; 95% CI, 1.25-1.44). The likelihood of experiencing a cardiovascular event was only 12% in participants who had not experienced one before taking varenicline. Varenicline contributed to 3.95 adverse cardiovascular events per 1,000 users. Sensitivity analyses confirmed these findings.
The incidence of neuropsychiatric events, including depression, anxiety, psychosis, hallucinations, insomnia and self-harm, was slightly increased with varenicline use (relative incidence = 1.06; 95% CI, 1-1.13). However, that these findings are not robust.
The researchers note that previous studies have revealed that varenicline increases the likelihood of an individual quitting smoking by three times and such long-term benefits should be considered when deliberating the potential risks.
“Increased awareness of neuropsychiatric adverse events due to [FDA] warnings during the time of this study may have led physicians and patients to increase monitoring for these complications thus preventing them from progressing to adverse events,” Gershon said in the interview. “This might mean our findings are only generalizable to people who receive such monitoring and the risk of varenicline is greater in those who do not.”
She added that primary care physicians should not see the findings as an across-the-board assumption to discontinue discussing varenicline with patients.
“We hope that primary care physicians will inform patients of possible cardiovascular risks so that they can make informed decisions as to whether or not they should use it,” she said. “We do not think primary care physicians should say categorically that varenicline should not be taken. Its risks should be considered in the context of the potential benefit of quitting smoking, which is considerable.”
The FDA had approved Pfizer’s removing of the boxed warning regarding serious neuropsychiatric events from Chantix in December 2016. Gershon told Healio Internal Medicine her and her colleagues’ research was not tied to the FDA decision. – by Alaina Tedesco and Janel Miller
Gershon reports being supported by a Fellowship for Translational Health Research from the Physicians’ Services Incorporated Foundation, Toronto, Ontario and a Canadian Institutes for Health Research New Investigator Award. Please see the study for the other authors’ relevant financial disclosures.