Monday, July 02, 2012

New Population-Based Study Shows that Effectiveness of Chantix and NRT is Much Lower than in Clinical Trials; Failure Rate is At Least 92%

A study published in this month's issue of the European Journal of Internal Medicine reports on the effectiveness of varenicline (Chantix) and nicotine replacement therapy (NRT) in a real-life setting: as prescribed for smoking cessation at two urban academic medicine centers.

See: Dhelaria RK, Friderici J, Wu K, Gupta E, Khan C, Rothberg MB. Effectiveness of varenicline for smoking cessation at 2 urban academic health centers. European Journal of Internal Medicine 2012; 23(5):461-4.

The article presents the results of a retrospective cohort study in which 371 patients who were prescribed either Chantix or NRT for smoking cessation were followed up to determine smoking status at one year.

The results were as follows: "Within one year, 247 (67%) had follow-up, and 26 (10.5%) maintained abstinence through week 52, 10.2% with varenicline and 10.8% with NRT (p=1.0). Loss to follow-up was 37% for varenicline, 31% for NRT (p=0.20). Including lost patients as smokers, the adjusted quit rates for varenicline and NRT were similar (6.5% vs. 7.6%, p=0.69)."

The study concludes: "In an inner city clinic, abstinence rates were lower than those in clinical trials and did not differ between varenicline and NRT."

The Rest of the Story

The results of this study stand in sharp contrast to a clinical trial which compared Chantix and NRT head-to-head over a one-year follow-up period. In that study, the one-year cessation rate was 26% for Chantix and 20% for NRT. In this study, outside of the clinical trial setting, the one-year cessation rate was just 6.5% for Chantix and 7.6% for NRT.

There are a number of reasons why the success of Chantix and NRT appear to be much lower in real-life settings than in clinical trials. The most important reason is that the subjects in clinical trials tend to be highly motivated to quit smoking. You have to go through a number of hoops, including making phone calls, reporting for clinic visits, undergoing screening, and reading and signing informed consent forms in order to be successfully recruited for a clinical trial. In no way do clinical trials take "all comers." In contrast, this (and other) population-based studies examine the experiences of "all comers." They examine everyone who attempts to quit using these methods, rather than just the most highly motivated.

Of course, it is the effectiveness in real-life settings that is most appropriate to use in assessing the true efficacy of these products and in making practice and policy decisions.

On its web site, Pfizer boasts that: "In studies, 44% of CHANTIX users were quit during weeks 9 to 12 of treatment (compared to 18% on sugar pill)."

While technically true, this is a misleading statistic to highlight for potential users. The site makes no mention of the fact that despite the 44% quit-rate over 3 months in the clinical trial setting, the actual long-term (one year) success rate for Chantix in real-life settings appears to be only about 6 or 7%. While the web site statistic might not be inappropriate in a consent form for a clinical trial, it does not seem appropriate for a general web site that one would infer is making generalizations about the use of Chantix in real-life settings outside of clinical trials.

While it is understandable that Pfizer is making misleading claims - after all, it is a pharmaceutical company and its mission is to sell its products - it not understandable why anti-smoking researchers, advocates, and groups are repeating the same misleading claims.

One explanation, of course, is the funding that Pfizer and other pharmaceutical companies have provided to tobacco control researchers and organizations. For example, as I have noted, the National Conference on Tobacco or Health, to be held next month in Kansas City, is sponsored by Pfizer. Another example is the American Legacy Foundation, which is a recipient of Pfizer money.

And the list goes on. The American Cancer Society and Action on Smoking and Health are recipients of Pfizer funding for tobacco control programs. The American Cancer Society also has this financial relationship with Pfizer. Pfizer reports a large number of grants in 2010 to the American Cancer Society, American Heart Association, American Lung Association, American Academy of Pediatrics, and Campaign for Tobacco-Free Kids here.

Additionally, Pfizer reports grants in 2009 to the American Legacy Foundation, along with the American Cancer Society, American Heart Association, American Lung Association, Campaign for Tobacco-Free Kids, Action on Smoking and Health, and American Academy of Pediatrics here

In addition, many individual anti-smoking researchers who have disseminated the misleading statistics about the effectiveness of Chantix and NRT have personal financial conflicts of interest with Big Pharma.

Also troubling, and even less understandable, is the failure of government agencies, such as the Department of Health and Human Services and its Centers for Disease Control and Prevention (CDC) to accurately convey the critical information to the public.

For example, CDC informs smokers that using drugs to quit can "double" their chances of success. This is only true in the clinical trial setting, and is not borne out in population-based studies or in real-life settings. Thus it is very misleading. It also fails to provide the absolute rates of success, which are dismal even though they may be "doubled" by the use of NRT. Going from a 4% chance of success to an 8% chance of success is hardly what a reader of this web site is going to envision as the truth based on the information presented by CDC.

The CDC web site, while recommending that every smoker use drugs to quit, fails to mention the potentially deadly side effects of Chantix. It also fails to discourage pregnant smokers from using NRT, merely advising them to talk to their doctors.

It turns out that even the CDC has a financial conflict of interest with Big Pharma in general, and Pfizer in particular. Who can ever forget this famous quote from the CDC Foundation: "We deeply appreciate our ongoing partnership with Pfizer to support CDC’s work to protect us all from dangerous and expensive health threats. Each public-partnership forged through the CDC Foundation helps CDC put science into action to save lives. We believe this innovative partnership, which was made possible by Pfizer, could substantially improve health for many individuals and communities."

It is also possible, I dare to say, that this innovative partnership (and similar ones throughout the anti-smoking movement) could substantially worsen health for many individuals and communities by leading to biased and misleading advice to smokers, misplaced policy priorities and approaches, and heavily biased, rather than objective, science-based communications, policies, and programs.

(Thanks to John Polito for the tip and for critical insights that I have incorporated into the piece.)

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