Healthy Skepticism Library item: 10614
Warning: This library includes all items relevant to health product marketing that we are aware of regardless of quality. Often we do not agree with all or part of the contents.
Publication type: news
O'Riordan M.
Pfizer Backtracks on the Benefit of Atorvastatin Over Simvastatin: 'Programming Error' in Flawed Study Cited
Heartwire 2007 Jun 18
http://www.medscape.com/viewarticle/558491?src=mp
Full text:
The availability of simvastatin as a generic drug for patients with high cholesterol levels expectedly put the heat on atorvastatin (Lipitor), Pfizer’s blockbuster statin that is still the world’s best-selling medication. In fending off simvastatin, sold by Merck and Co as Zocor, Pfizer has claimed that its drug prevents more cardiovascular events than the generically available simvastatin.
That was the gist of a press release issued by Pfizer this past March, a release based on a study by Dr Robert Vogel (University of Maryland, Baltimore) and presented at the American Heart Association’s annual conference on Cardiovascular Disease Epidemiology and Prevention. In that study, Pfizer said that among those taking statins for at least three months, the risk of cardiovascular events, after adjustment for dose, was 14% lower in patients who took atorvastatin compared with simvastatin.
Now, however, the company is backing away from those findings, claiming that the benefit observed in the study was just 10%, a between-treatment difference that did not meet statistical significance. Pfizer issued a two-paragraph statement with the Securities Exchange Commission (SEC) stating the previous findings were incorrect, the result of a “programming error” that came to light only after the study was submitted to an unnamed medical journal, according to the Wall Street Journal [1].
Large 80 000-patient database
The erroneous findings emerged from data taken from a large managed-care-organization group of patients who had taken either atorvastatin or simvastatin. Within this cohort of approximately 80 000 patients, investigators compared the rate of cardiovascular events, including MI and stroke, in those taking the different drugs. Trumpeting Lipitor, Pfizer stated that the study is “significant because it calls into question whether statins should be prescribed interchangeably through simple dose adjustments.”
Vogel is quoted in the Pfizer-issued press release as saying the “analysis is important for physicians, employers, and formulary directors at managed-care companies who are making real-world treatment decisions for patients.”
This week’s SEC filing now states that the observed 14% greater reduction with atorvastatin is incorrect and the overall benefit is not statistically significant. A secondary end point, while also corrected, did still meet statistical significance.
Zocor lost patent protection June 23, 2006, and immediately sales of the generic versions of simvastatin increased, with the drug taking market share away from atorvastatin. Dr Christopher Cannon (Brigham and Women’s Hospital, Boston, MA) previously told heartwire that generic statins have become the de facto choice for any patient needing a standard amount of lipid lowering. Dr Steven Nissen (Cleveland Clinic, OH) hailed the availability of generic simvastatin as a giant step forward.
Still, despite the availability of a generic statin, most experts, including Cannon and Nissen, do not believe a “one-size-fits-all approach” should be used and that clinicians shouldn’t be strong-armed by payers to put all patients on a generic, especially high-risk patients in need of a more potent agent.
Goldstein J. Pfizer backtracks on Lipitor’s edge over rival. Wall Street Journal health blog, June 14, 2007. Available at: http://blogs.wsj.com/health.
