Melbourne, Australia—The use of daily low-dose aspirin is of concern because it is known to increase the risk of major bleeding. But what about the effect on iron deficiency and anemia?

A review conducted by researchers in Australia and New Zealand but partly funded by the U.S. National Institutes of Health sought to investigate the effect of low-dose aspirin on incident anemia, hemoglobin, and serum ferritin concentrations.

The study was a post hoc analysis of the ASPREE (ASPirin in Reducing Events in the Elderly) randomized, controlled trial. That trial looked at primary/community care in Australia and the United States and involved adults aged 70 years and older—or aged older than 65 years for those who were black or Hispanic—who lived in the community. The results were published in Annals of Internal Medicine.

After more than 19,000 participants took either 100 mg of aspirin or placebo daily, hemoglobin concentration was measured annually. Ferritin was measured at baseline and 3 years after random assignment in a large subset.

The results indicated that anemia incidence in the aspirin and placebo groups was 51.2 events and 42.9 events per 1,000 person-years, respectively (hazard ratio, 1.20 [95% CI, 1.12-1.29]). Hemoglobin concentrations declined by 3.6 g/L per 5 years in the placebo group and the aspirin group experienced a steeper decline by 0.6 g/L per 5 years (CI, 0.3-1.0 g/L).

“In 7139 participants with ferritin measures at baseline and year 3, the aspirin group had greater prevalence than placebo of ferritin levels less than 45 µg/L at year 3 (465 [13%] vs. 350 [9.8%]) and greater overall decline in ferritin by 11.5% (CI, 9.3% to 13.7%) compared with placebo,” the researchers wrote. “A sensitivity analysis quantifying the effect of aspirin in the absence of major bleeding produced similar results.”

A limitation of the study was that hemoglobin was measured annually, and no data were available on the direct causes of anemia.

“Low-dose aspirin increased incident anemia and decline in ferritin in otherwise healthy older adults, independent of major bleeding,” the authors concluded. “Periodic monitoring of hemoglobin should be considered in older persons on aspirin.”

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