Beta-Blockers Don't Reduce Deaths Among Low-Risk Surgical Patients
By Neil Osterweil , MedPage Today Staff Writer - Reviewed by Robert Jasmer, MD; Assistant Professor of Medicine, University of California, San Francisco
Source News Article: Atlanta Journal-Constitution (Registration Req.), MSNBC, Washington Post (Registration Req.)
MedPage Today Action Points •
Advise patients that beta-blockers are effective and safe, and appear to lower the risk of myocardial infarction following major non-cardiac surgery in patients with a high-risk of coronary artery disease, but may not be appropriate in low-risk patients undergoing similar procedures. •
Inform patients that this was a retrospective observational study and is subject to statistical variations and errors. Randomized clinical trials currently underway may produce clearer answers about the role of beta-blockers in reducing in-hospital mortality following non-cardiac surgery.
SPRINGFIELD, Mass., July 27-The value of beta-blockers in reducing mortality after high-risk heart surgery doesn't extend to patients who have low risk non-cardiac procedures, researchers reported today.
Giving the same drugs to patients at low or medium surgical risk doesn't help, and could harm, according to University of Massachusetts and Tufts Medical School researchers in a report in the July 28 issue of the New England Journal of Medicine.
Their retrospective observational study compared outcomes among nearly 120,000 patients scheduled for non-cardiac surgeries who received beta-blockers, and more than 216,000 similar patients who didn't get the drugs at or near the time of surgery.
They found that although beta-blockers appeared to reduce in-hospital deaths among highest cardiac risk patients by about 42%, the use of the drugs was associated with no benefit or possible harm among patients in the lowest cardiac-risk categories, wrote Peter K. Lindenauer, M.D., and colleagues.
Both the American Heart Association and American College of Cardiology recommend the use of beta-blockers in patients with either proven coronary artery disease or coronary risk factors who are scheduled for any type of high-risk procedures. The recommendations are based in part on two studies published in the late 1990s, which indicated that beta-blockers can reduce the incidence of myocardial infarction and death following non-cardiac operations.
In an editorial accompanying the study, Don Poldermans, M.D., and Eric Boersma, Ph.D., of Erasmus Medical Center in Rotterdam, The Netherlands, spelled out the rationale for perioperative beta-blocker use among at-risk patients.
"In patients with clinically significant coronary-artery stenosis, myocardial ischemia is induced either by a prolonged mismatch between oxygen demand and supply owing to the stress of surgery or as the result of a sudden rupture of a vulnerable plaque followed by thrombus formation and occlusion. Beta-blockers are commonly used to correct the imbalance between myocardial oxygen demand and supply," the editorialists wrote. They were the lead authors on earlier studies indicating a benefit of beta-blockers among patients undergoing surgery.
Beta-blockers appear to be effective and safe and are relatively cheap, and the National Quality Forum, a non-profit group dedicated to monitoring healthcare quality, has put them on its list of "30 Safe Practices for Better Healthcare," Dr. Lindenauer and colleagues noted.
"Yet, two recent randomized trials reported no benefit from perioperative beta-blocker therapy and raised questions about the generalizability of earlier studies," they wrote.
To evaluate the use and effectiveness of perioperative beta-blocker therapy in routine clinical practice, they conducted a retrospective cohort study based on data drawn from 329 hospitals across the United States. The cohort included patients 18-years-old and up who underwent major non-cardiac surgery in 2000 or 2001.
They used propensity-score matching to account for differences between patients who received perioperative beta-blockers and those who did not, and they used multivariate logistic modeling to compare in-hospital mortality rates. Cardiac risks were determined by scores on the Revised Cardiac Risk Index (RCRI), in which a score of 0 equals no risk, and a score of 4 or higher equals high risk.
Patients were considered to have received beta-blockers perioperatively if they received them within the first two hospital days. In all, 119,632 patients out of a total cohort of 782,969 received perioperative beta-blockers and could be matched with at least one patient who either didn't get a beta-blocker or received it after the second hospital day.
The investigators found that for patients with an RCRI score of 2 or greater, beta-blocker treatment was associated with a reduced risk of death, with patients in highest risk category (RCRI = 4) having an odds ratio of 0.57 (95% CI, 0.42-0.76). In contrast, patients with an RCRI of 0 had an increased risk of in-hospital death, as indicated by an OR of 1.43 (95% CI, 1.29-1.58).
Odds ratios for the other categories fell in between the two extremes in a stepwise fashion.
"Our results extend the findings from these earlier studies and provide support for the perioperative use of beta-blockers in high-risk patients, while we await the results of a large, ongoing, randomized trial," Dr. Lindenauer and colleagues wrote. "Yet the lack of benefit of this approach in moderate-risk patients and the potential harm of this approach in the lowest- risk groups suggest that careful patient selection remains necessary."
The role of beta-blockers in low-to-intermediate risk patients is currently being studied in two large randomized clinical trials, Drs. Poldermans and Boersma noted.
"Pending the availability of data from these trials (expected within four years), we believe it is appropriate to continue beta-blocker therapy in patients at low or intermediate risk, given the potential cardiac risks associated with the sudden interruption of beta-blocker therapy," they wrote. "Further information is needed before the perioperative use of beta-blockers should be considered routinely in other patients at low or intermediate risk."
Primary source: New England Journal of Medicine - Source reference: N Engl J Med 2005;353:349-61
Additional source: New England Journal of Medicine - Source reference: N Engl J Med 2005;353:412-13
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