Daily Aspirin Doing More Harm Than Good in Women

In healthy women, the cons of taking daily low-dose aspirin to prevent heart disease, cancer, and other serious illness outweigh the pros.

In healthy women, the cons of taking daily low-dose aspirin to prevent heart disease, cancer, and other serious illness outweigh the pros, according to research published online in Heart.

Researchers from the University Medical Centre Utrecht in the Netherlands examined nearly 30,000 healthy women aged at least 45 years who participated in the Women’s Health Study. In the study, subjects were assigned to receive either 100 mg of aspirin or placebo every other day to test whether aspirin curbed the risk of heart disease, stroke, and/or cancer.

The participants were observed for 10 years, and during that time, the following disorders were diagnosed:

- 604 cases of cardiovascular disease

- 168 cases of bowel cancer

- 1832 cases of other cancers

- 302 major gastrointestinal bleeding incidents requiring hospital admission

After 7 more years of observation, 107 additional cases of bowel cancer and 1388 further cancer cases were diagnosed.

Nevertheless, the researchers concluded that regular low-dose aspirin use was linked to a reduced risk of heart disease, stroke, and bowel cancer compared with placebo, especially in women aged older than 65 years. However, about two-thirds of those taking the non-steroidal anti-inflammatory drug experienced internal gastrointestinal bleeding, and among women aged 65 years and older, the risk for gastrointestinal bleeding, bowel cancer, and cardiovascular disease increased with age.

Additionally, the researchers calculated that over 15 years, 29 women aged older than 65 years would require an aspirin regimen in order to prevent a single case of cancer or heart disease and/or stroke.

“Recent findings that both daily and alternate day aspirin can reduce cancer risk, particularly for colorectal cancer, have reignited the debate on aspirin in primary prevention,” wrote the authors, who added that blanket aspirin treatment is “ineffective or harmful in the majority of women with regard to the combined risk of cardiovascular disease, cancer, and major gastrointestinal bleeding.”

The current literature suggests that daily and alternate day aspirin regimens can reduce the risk of colorectal cancer and other cancers, and many studies agree that aspirin regimens modestly lower cardiovascular risks, yet increase the risk of major gastrointestinal bleeding episodes.

“Age is the most important determinant of aspirin treatment effect, and the protective effects of aspirin with regard to cardiovascular disease increased with age,” the investigators concluded. “Although the excess risk of major gastrointestinal bleeding by aspirin is higher in women ≥65 years of age, selective treatment of this group may improve net benefit.”