"Long before it's in the papers"
October 18, 2007

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Aspirin against heart disease: just for men?

Oct. 18, 2007
Courtesy BioMed Central
and World Science staff

First it was an ap­ple; now it’s a small as­pi­rin a day that may keep the doc­tor away. As­pi­rin has be­come stand­ard for heart at­tack pre­ven­tion. 

But new re­search sug­gests it may really be a man’s drug.

Sci­en­tists have long puz­zled over why as­pi­rin’s pro­tec­tive ef­fects vary widely among clin­i­cal tri­als. Some stud­ies find it has no spe­cial ef­fect; oth­ers, that it cuts heart at­tack risk by over 50 per­cent.
A new study from re­search­ers at St. Paul’s Hos­pi­tal in Van­cou­ver, Can­a­da, high­lights the in­flu­ence of gen­der. In­ves­ti­ga­tors ex­am­ined 23 pre­vi­ously pub­lished clin­i­cal tri­als, in­volv­ing more than 113,000 pa­tients, and an­a­lysed how the pro­por­tion of men to wom­en af­fect­ed the the out­comes.

“Tri­als that re­cruited pre­dom­i­nantly men dem­on­strat­ed the larg­est risk re­duc­tion in non-fatal heart at­tacks,” said Don Sin, one of the au­thors. 

“The tri­als that con­tained pre­dom­i­nately wom­en failed to dem­on­strate a sig­nif­i­cant risk re­duc­tion in these non-fatal events. We found that a lot of the vari­abil­ity in these tri­als seems to be due to the gen­der ra­tios, sup­port­ing the the­o­ry that wom­en may be less re­spon­sive to as­pi­rin than men for heart pro­tec­tion.”

The rea­sons why are un­clear, he said, though re­cent stud­ies have shown that men and wom­en have ma­jor dif­fer­ences in the heart’s blood ves­sels.

“We would cau­tion clin­i­cians on pre­scrib­ing as­pi­rin to wom­en, es­pe­cially for pri­ma­ry pre­ven­tion of heart at­tacks,” said Sin. “Whether or not oth­er phar­ma­ceu­ti­cal prod­ucts would be more ef­fec­tive for wom­en is un­clear; more sex-specific stud­ies should now be con­duct­ed.” The find­ings ap­peared Oct. 18 in the on­line re­search jour­nal BMC Med­i­cine.

A study pub­lished in the Jour­nal of the Amer­i­can Med­i­cal As­socia­t­ion last May re­com­mended 75 to 81 mil­ligrams of as­pi­rin dai­ly, tak­en in con­sulta­t­ion with a phy­si­cian, for long-term heart dis­ease and stroke pre­ven­tion.

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First it was an apple; now it’s a small aspirin a day that may keep the doctor away. Aspirin has become standard for heart attack prevention. But new research suggests it may really be a man’s drug. Scientists have long puzzled over why aspirin’s protective effects vary widely between clinical trials. Some studies show show aspirin is no better than a placebo; others, that it cuts heart attack risk by over 50%. A new study from researchers at St. Paul’s Hospital in Vancouver, Canada, highlights the influence of gender. Investigators examined 23 previously published clinical trials, involving more than 113,000 patients, and analysed how the ratio of men to women affected the the various outcomes. “Trials that recruited predominantly men demonstrated the largest risk reduction in non-fatal heart attacks,” said Don Sin, one of the authors. “The trials that contained predominately women failed to demonstrate a significant risk reduction in these non-fatal events. We found that a lot of the variability in these trials seems to be due to the gender ratios, supporting the theory that women may be less responsive to aspirin than men for heart protection.” The reasons why are unclear, he said, though recent studies have shown that men and women have major differences in the heart’s blood vessels. “We would caution clinicians on the prescribing aspirin to women, especially for primary prevention of heart attacks,” said Sin. “Whether or not other pharmaceutical products would be more effective for women is unclear; more sex-specific studies should now be conducted.” The findings appeared Oct. 18 in the online research journal BMC Medicine. A study published in the Journal of the American Medical Association last May recommended 75 to 81 milligrams of aspirin daily, taken in consultation with a physician, for long-term heart disease and stroke prevention.