The popular smoking-cessation drug Chantix does not increase the risk of heart attacks, strokes and other cardiovascular problems, according to a UCSF study that challenges an earlier, widely circulated report that suggested the medication was dangerous.
The new study, published Thursday in the British Medical Journal, found no significant difference in rates of heart attacks and other serious events between smokers who used Chantix and those who didn’t.
The results reassured many doctors and other health care providers who had worried about the drug’s safety and wondered whether it should be removed from the market, despite the fact that drugs that help people stop smoking are in short supply, and Chantix is among the most successful.
The authors of the earlier study, published in July 2011, said they stand by their results, which found that Chantix users were far more likely to suffer cardiovascular events than those who didn’t use the drug.
But the UCSF researchers said this week that their study – an analysis of 22 clinical trials involving more than 9,000 patients – proves that Chantix is safe and should be promoted to help people stop smoking.
“This study gives us a firm understanding of what’s going on” with Chantix, said Judith Prochaska, lead author of the UCSF study and a researcher with the university’s Center for Tobacco Control Research and Education. “When I looked at the first paper, the numbers seemed really strange. It made me want to look at them further and reanalyze.”
Long-term cigarette smoking causes serious heart problems, and most people who die from smoking have heart attacks or strokes. Quitting offers almost immediate benefits, even for long-term smokers, but smoking is a notoriously difficult habit to break.
Three types of drugs have been approved by the U.S. Food and Drug Administration to help people quit: nicotine replacement drugs, such as the patch and nicotine gum; bupropion, an antidepressant; and varenicline, which is sold as Chantix.
Chantix, made by Pfizer and approved by the FDA in 2006, works by numbing some of the symptoms of nicotine withdrawal, in addition to reducing the pleasurable sensations from smoking. Chantix is considered one of the most effective drugs to help people quit, although its success rates are fairly low, between 19 and 47 percent, according to one recent study.
The new study does not address some of the other concerns around Chantix – notably, its association with psychiatric problems, including reports of people becoming depressed and even suicidal while taking the drug. Chantix prescriptions come with strong warnings, mandated by the FDA, about the possibility of psychiatric problems.
Chantix catches on
The drug has been controversial since it came onto the market, and early research pointed to a possible increased risk of cardiovascular problems for patients who already had heart disease. But even so, it quickly became one of the most popular antismoking medications on the market.
After the 2011 study, the FDA ordered another analysis of cardiac risk. The government’s analysis is being reviewed and is expected to be released later this year.
“It hasn’t really changed whether or not I prescribe the medication that works the best for my patients. But I know that there are a lot of physicians that were alarmed and probably have stopped prescribing it,” said Dr. Sean David, a Stanford clinical associate professor whose research is focused on smoking cessation. “Hopefully this new study will help physicians reconsider.”
Both the new study and the 2011 study are meta-analyses, where researchers gather data from other clinical trials, which bolsters the results by forming a much larger pool of patients. The earlier study involved 14 clinical trials and 8,200 patients, compared with the 22 trials and 9,200 patients in the UCSF study.
The 2011 study found that 1.06 percent of patients taking Chantix had a heart attack or other cardiovascular event, compared with 0.82 percent of patients not using the drug. When the researchers weighted the clinical trials based on a number of factors, the end result was that Chantix users had a 72 percent increased risk of cardiovascular problems, a number that the UCSF authors, who found similar rates of cardiovascular events in their study, argue was inappropriately inflated, Prochaska said.
Regardless, she said, there were very few incidents of serious heart problems in either group of patients.
Prochaska has a grant from Pfizer to study the drug in a hospital setting, although she said no money from the company went toward the report published this week. She said she decided to perform the meta-analysis before starting her hospital study because “I did not want to be taking on any liability with a drug that may be unsafe.”
“I feel confident with our findings and I will use it now,” Prochaska said.
Matter of debate
Dr. Sonal Singh, an assistant professor of medicine at Johns Hopkins University who was lead author of the 2011 study, agreed that the discrepancies between the two studies are mostly a matter of number-crunching. But he believes that his results are the more appropriate, and he has no doubt that Chantix increases the risk of heart problems.
“I commend them for doing their study, but I think they’re wrong,” Singh said.
That doesn’t mean the drug should be taken off the market, he said. But it should be used very cautiously.
“We need to be balanced about this,” he said. “We need to consider the benefits of quitting – and there are substantial benefits – against the risks.”