British Find Less Support for Aspirin : Say Study Uncovered No Proof Usage Cuts Risk of Heart Attack

A six-year study of more than 5,000 British doctors finds no evidence that aspirin can cut heart attack risk but does not directly contradict an American study that found aspirin could cut heart attack risk in half, researchers said today.

The reason, said the director of the American study, is that the British study included too few participants.

“You don’t have enough heart attacks in the group to distinguish with great assurance whether nothing is going on or whether there’s a small to moderate effect,” said Dr. Charles H. Hennekens of Harvard University in Cambridge, Mass.

The British study was published today in the British Medical Journal.

The American study, published Thursday in the New England Journal of Medicine, included 22,000 U.S. doctors. It found that an aspirin taken every other day can cut the risk of heart attack by 47%.

Calls Findings Consistent

Sir Richard Doll, professor emeritus of medicine at Oxford University, who took part in the British research, said that despite the different results, his findings were consistent with those of the American team.

Hennekens, who collaborated with the British on their study and sought their help on his, explained why the two studies were consistent.

The British study, he said, does not show that aspirin offers no protection. It concluded that aspirin could produce, at most, a one-third drop in heart attack risk.

The U.S. study estimated a 47% drop in heart attack risk, but allowed that the reduction in risk might be as low as 30%. Thus there is overlap between the findings of the two studies, Hennekens said.

That is what the researchers mean by saying the studies are consistent, he added.

Doll said he is certain aspirin can help prevent heart attacks, although acknowledging that his research did not produce supporting evidence.

The British study involved 5,139 doctors over a six-year period from 1978. Among the 3,429 who took aspirin daily, 148 died from heart attack or stroke. Among the 1,710 who did not take aspirin, 79 died of heart attack or stroke.

Favors Positive Findings

The British researchers pointed out that the U.S. study found about three times as many non-fatal heart attacks as the British study. “So the positive result from the United States carries more weight than the null result from the United Kingdom,” they wrote.

For that reason, the collective results indicate the benefit to middle-aged men of taking aspirin daily might be to reduce the risk of non-fatal heart attacks by about one-third, the Oxford team said.

The British researchers said their study does not provide a final balance of the exact benefits and hazards of aspirin use by apparently healthy people.