Study Compares Cardiovascular Events, Stroke in Patients Prescribed Beta-Blockers for Hypertension

CHICAGO – A study that compared the incidence of myocardial infarction (MI, heart attack), stroke and heart failure in patients with hypertension who were newly prescribed two β (beta)-blocker drugs suggests there were no significant differences in cardiovascular events between patients who took atenolol or metoprolol tartrate, according to a report published Online First by Archives of Internal Medicine, a JAMA Network publication.

Randomized controlled trials have shown selected β-blockers to be effective for preventing cardiovascular (CV) events in patients after MI or with heart failure (HF), but the effectiveness of the medications for preventing CV events in patients with hypertension has been questioned, although it is unclear whether that applies to the entire β-blocker class. Two large clinical trials have suggested that atenolol-based regimens were less effective than other antihypertensive drugs for preventing CV events in patients with hypertension, according to the study background.

Emily D. Parker, M.P.H., Ph.D., of HealthPartners Institute for Education and Research, Minneapolis, Minn., and colleagues used electronic medical record and health data from the Cardiovascular Research Network Hypertension Registry (which includes patients from three large integrated health care delivery systems in Minnesota, Colorado and California) to compare the occurrence of MI, HF and stroke in patients who were new β-blocker users between 2000 and 2009. A total of 120,978 patients without a history of cardiovascular disease (CVD) events started treatment. Atenolol was used by approximately 10 times more patients than metoprolol tartrate, according to study results.

“In this retrospective cohort study comparing patients initiating β-blocker treatment with either atenolol or metoprolol tartrate, there were no statistically significant differences in rates of incident MI, HF or stroke after adjusting for potential confounders,” the authors comment.

During follow-up (median 5.2 years), there were 3,517 incident MIs, 3,272 HF hospitalizations and 3,664 incident strokes. Hazard ratios for MI, HF and stroke in metoprolol tartrate users were 0.99 for each, respectively, the results indicate.

“In conclusion, we found no differences in CV event rates when comparing patients without a history of CV events who were initiating treatment with either atenolol or metoprolol tartrate,” the authors conclude. “These findings suggest that hypertension trial outcomes with atenolol may not relate to unfavorable characteristics of this particular drug. These results should be interpreted cautiously, since there have been no trials comparing these two β-blockers directly.”

(Arch Intern Med. Published online August 27, 2012. doi:10.1001/archinternmed.2012.4276. Available pre-embargo to the media at http://media.jamanetwork.com.)

Editor’s Note: The project was funded by a grant from the National Heart, Lung and Blood Institute and subcontract to HealthPartners Institute for Education and Research. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Commentary: Observational Comparative Effectiveness Studies of Drug Therapies

In a commentary, James S. Floyd, M.D., M.S., and Bruce M. Psaty, M.D., Ph.D., University of Washington, Seattle, write: “Although low-dose diuretics are the recommended first-line agent for pharmacologic therapy for uncomplicated high blood pressure, several large trials funded by the pharmaceutical industry have used β-blockers as the active-comparison control treatment, and the results of these trials suggest that other therapies are more effective than atenolol in preventing cardiovascular events, particularly stroke.”

“Because no primary prevention trial among hypertensive patients has compared atenolol head to head with other β-blockers, their comparative effectiveness in this setting remains unknown. To address this question, Parker and colleagues conducted an observational study that compared the new use of atenolol and metoprolol tartrate, two widely used β-blockers in theUnited States, for the prevention of MI, stroke and [congestive heart failure] CHF in patients with treated hypertension,” they continue.

“While careful attention to study design is necessary for the results of observational comparative effectiveness studies to be credible, the high-quality answers may not involve the more important clinical questions, and the key clinical questions may not be susceptible to high-quality answers. For many or most comparative effectiveness questions related to drug therapies, double-blinded randomized trials will be required to obtain high-quality evidence,” they conclude.

(Arch Intern Med. Published online August 27, 2012. doi:10.1001/archinternmed.2012.4306. Available pre-embargo to the media at http://media.jamanetwork.com.)

Editor’s Note: Psaty made financial disclosures and both received grant support from the National Heart, Lung and Blood Institute. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

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For more information, contact JAMA Network Media Relations at 312-464-JAMA (5262) or email mediarelations@jamanetwork.org.
 

Media Advisory: To contact Emily D. Parker, M.P.H., Ph.D., call Mary Van Beusekom at 952-967-7361 or email Mary.B.VanBeusekom@HealthPartners.com. To contact corresponding commentary author James S. Floyd, M.D., M.S., call Leila Gray 206-685-0381 or email leilag@uw.edu.

Posted: August 2012

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