Impact of low-dose aspirin on the prevalence of anemia in elderly patients: a systematic review and meta-analysis

Aspirin is largely used for cardiovascular prevention. While its adverse effect on bleeding is well-documented, the prevalence of anemia remains uncertain. We conducted a meta-analysis on how low-dose aspirin affects hemoglobin and other hematologic parameters in the elderly. We systematically searched PubMed, Embase, and Cochrane for studies comparing the hematological parameters and the prevalence of anemia between low-dose aspirin (≤325 mg) and non-aspirin users in individuals aged older than 60 years. We pooled mean differences (MD) for continuous outcomes and odds ratio (OR) for binary outcomes, with 95% confidence intervals (CI), under a random-effects model for both. Seven studies were included, including three randomized controlled trials (RCTs), totaling 19,792 participants. Among them, 9,771 (49.3%) were treated with aspirin; 55.4% were women and 44% had a history of smoking. There was no significant difference in anemia prevalence (OR 0.85; 95% CI 0.52–1.38; p = 0.50). Mean Corpuscular Hemoglobin (MD 0.06 pg; 95% CI −0.37 to 0.49; p = 0.79), Mean Corpuscular Volume (MD −0.31 fl; 95% CI −1.17 to 0.56; p = 0.49), and hemoglobin concentration (MD −0.02 g/dL; 95% CI −0.26 to 0.21; p = 0.85) between the two groups. However, hemoglobin decline from baseline was higher in aspirin users (MD −0.11 g/dL; 95% CI −0.17 to −0.05; p = 0.0002; I2 = 0%). Our study employs rigorous methodology and a substantial patient cohort, marking the first quantitative meta-analysis in the past decade. Limitations include diverse study designs, short follow-up durations, gender-specific anemia criteria, and insufficient ferritin and iron levels data. Nonetheless, our findings suggest that while low-dose aspirin does not increase anemia prevalence, it is associated with declining hemoglobin levels over time.