Effect of Low-Dose Aspirin Versus Placebo on Incidence of Anemia in the Elderly

Background: Daily low-dose aspirin increases major bleeding; however, few studies have investigated its effect on iron deficiency and anemia. Objective: To investigate the effect of low-dose aspirin on incident anemia, hemoglobin, and serum ferritin concentrations. Design: Post hoc analysis of the ASPREE (ASPirin in Reducing Events in the Elderly) randomized controlled trial. (ClinicalTrials. gov: NCT01038583) Setting: Primary/community care in Australia and the United States. Participants: Community-dwelling persons aged 70 years or older (≥65 years for Black persons and Hispanic persons). Intervention: 100 mg of aspirin daily or placebo. Measurements: Hemoglobin concentration was measured annually in all participants. Ferritin was measured at baseline and 3 years after random assignment in a large subset. Results: 19 114 persons were randomly assigned. Anemia incidence in the aspirin and placebo groups was 51.2 events and 42.9 events per 1000 person-years, respectively (hazard ratio, 1.20 [95% CI, 1.12 to 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 to 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 mg/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. A sensitivity analysis quantifying the effect of aspirin in the absence of major bleeding produced similar results. Limitations: Hemoglobin was measured annually. No data were available on causes of anemia. Conclusion: Low-dose aspirin increased incident anemia and decline in ferritin in otherwise healthy older adults, independent of major bleeding. Periodic monitoring of hemoglobin should be considered in older persons on aspirin.