Aspirin cuts heart attacks, but not deaths or strokes: study

(Reuters Life!) - Small doses of aspirin can lower the risk of heart attacks in people who never had heart disease, but the blood-thinning drug doesn't appear to cut the chances of strokes or dying from the disease, according to a study.

And people should consult their doctors before taking the medication, which increases the risk of bleeding ulcers.

"Aspirin decreased the risk for cardiovascular events and nonfatal myocardial infarction in this large sample," wrote Alfred Bartolucci, from the School of Public Health at the University of Alabama and leader of the study, and colleagues.

"Thus, primary prevention with aspirin decreased the risk for total cardiovascular events and nonfatal myocardial infarction, but there were no significant differences in the incidences of stroke, cardiovascular mortality, all-cause mortality and total coronary heart disease."

The study, published in the American Journal of Cardiology, pooled the results of nine trials that tested aspirin in the prevention of heart disease so far. It was supported by aspirin maker Bayer AG.

The study included three trials that weren't part of the review by the U.S. Preventive Services Task Force that led to 2009 aspirin recommendations.

About 100,000 men and women aged 45 and up took part in the studies. Some were healthy and some had diabetes, but none had chest pain or other symptoms of an ailing heart.

The study found a 19 percent reduction in non-fatal heart attacks among participants who took aspirin compared to those who did not.

It didn't mention how many people actually suffered such a heart attack, but an earlier analysis of six of the trials showed that out of every 1,000 people, 18 people taking aspirin had heart attacks every year, compared to 23 taking placebo pills.

That analysis also found that aspirin increased the rate of bleeding from 0.7 to 1 per 1,000 people every year, making the authors conclude the drug was of "uncertain net value."

The current study also reported small decreases in stroke and death risks with aspirin, but said those changes might have been due to chance.

"It refines our knowledge of how beneficial aspirin is," said Graham Nichol, at the University of Washington in Seattle, who was not involved with the study.

"There is not universal agreement on what is high risk," he told Reuters Health, noting that aspirin is clearly beneficial for people who have already had heart disease.

"In my mind, if you have diabetes or multiple risk factors for heart disease, such as smoking or obesity -- it is reasonable to take aspirin."

But other experts said that patients needed to establish what their overall risk of heart attack was, and that a blanket recommendation to take aspiring was not a good idea.

Meta-Analysis of Multiple Primary Prevention Trials of Cardiovascular Events Using Aspirin

Alfred A. Bartolucci PhDa, Corresponding Author Contact Information, E-mail The Corresponding Author, Michal Tendera MDb and George Howard DrPHa

a Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama

b 3rd Division of Cardiology Medical University of Silesia, Katowice, Poland
Received 14 December 2010;
revised 12 February 2011;
accepted 12 February 2011.
Available online 8 April 2011.

Several meta-analyses have focused on determination of the effectiveness of aspirin (acetylsalicylic acid) in primary prevention of cardiovascular (CV) events. Despite these data, the role of aspirin in primary prevention continues to be investigated. Nine randomized trials have evaluated the benefits of aspirin for the primary prevention of CV events: the British Doctors' Trial (BMD), the Physicians' Health Study (PHS), the Thrombosis Prevention Trial (TPT), the Hypertension Optimal Treatment (HOT) study, the Primary Prevention Project (PPP), the Women's Health Study (WHS), the Aspirin for Asymptomatic Atherosclerosis Trial (AAAT), the Prevention of Progression of Arterial Disease and Diabetes (POPADAD) trial, and the Japanese Primary Prevention of Atherosclerosis With Aspirin for Diabetes (JPAD) trial. The combined sample consists of about 90,000 subjects divided approximately evenly between those taking aspirin and subjects not taking aspirin or taking placebo. A meta-analysis of these 9 trials assessed 6 CV end points: total coronary heart disease, nonfatal myocardial infarction (MI), total CV events, stroke, CV mortality, and all-cause mortality. No covariate adjustment was performed, and appropriate tests for treatment effect, heterogeneity, and study size bias were applied. The meta-analysis suggested superiority of aspirin for total CV events and nonfatal MI, (p <0.05 for each), with nonsignificant results for decreased risk for stroke, CV mortality, and all-cause mortality. There was no evidence of a statistical bias (p >0.05). In conclusion, aspirin decreased the risk for CV events and nonfatal MI in this large sample. Thus, primary prevention with aspirin decreased the risk for total CV events and nonfatal MI, but there were no significant differences in the incidences of stroke, CV mortality, all-cause mortality and total coronary heart disease.