Low-Dose Aspirin Linked to Lower Risk for All-Cause Mortality in Women

March 30, 2007 — Use of low-dose aspirin is linked to lower risk for all-cause mortality in women, especially older women and those with cardiac risk factors, according to the results of a study reported in the March 26 issue of the Archives of Internal Medicine.

"The influence of long-term use of aspirin on total mortality in women remains uncertain," write Andrew T. Chan, MD, MPH, from Massachusetts General Hospital and Harvard Medical School in Boston, and colleagues. "Although considerable evidence suggests that aspirin therapy improves survival in men and women with established cardiovascular disease, data for women without cardiovascular disease are limited and conflicting. Recently, a randomized trial of almost 40,000 apparently healthy women did not find a significant benefit of low-dose aspirin therapy on mortality."

In this prospective, nested, case-control study, 79,439 women enrolled in the Nurses' Health Study who had no history of cardiovascular disease or cancer provided data on medication use biennially since 1980. Relative risk (RR) of death according to aspirin use was determined before diagnosis of incident cardiovascular disease or cancer and during the corresponding period for each control subject.

During 24 years, there were 9477 deaths documented from all causes. Compared with women who never used aspirin regularly, women who reported current aspirin use had a multivariate RR of death from all causes of 0.75 (95% confidence interval [CI], 0.71 - 0.81). Risk reduction was more evident for death from cardiovascular disease (RR, 0.62; 95% CI, 0.55 - 0.71) than for death from cancer (RR, 0.88; 95% CI, 0.81 - 0.96).

Aspirin use for 1 to 5 years was associated with a significant reduction in cardiovascular mortality (RR, 0.75; 95% CI, 0.61 - 0.92), whereas a significant reduction in risk for cancer deaths was not observed until after 10 years of aspirin use (P for linear trend = .005). The benefit associated with aspirin was confined to low and moderate doses, and it was greater in older women (P for interaction < .001) and in women with more cardiac risk factors (P for interaction = .02).

"In women, low to moderate doses of aspirin are associated with significantly lower risk of all-cause mortality, particularly in older women and those with cardiac risk factors," the authors write. "A significant benefit is evident within 5 years for cardiovascular disease, whereas a modest benefit for cancer is not apparent until after 10 years of use."

Study limitations include observational design, self-selected aspirin use, possible residual confounding, inability to determine causality, and ability to assess the effect of aspirin only on fatal outcomes.

"Although aspirin therapy seemed to have a benefit against death from cancer, the effect was relatively modest, requiring prolonged use," the authors conclude. "Because our study was observational, these results should be interpreted cautiously and are insufficient evidence to alter current clinical recommendations. Nevertheless, these data support a need for continued investigation of the use of aspirin for chronic disease prevention."

The National Institutes of Health, the National Cancer Institute, an American Gastroenterological Association/Foundation for Digestive Health and Nutrition Research Scholar Award, and a GlaxoSmithKline Institute for Digestive Health Research Award supported this study. The authors have disclosed no relevant financial relationships.

Arch Intern Med. 2007;167:562-572.

Source: http://www.medscape.com/viewarticle/554356?src=mp