Effects of Aspirin per Bodyweight and Dose

Study Questions:

What are the clinical effects of aspirin therapy according to body weight and dose?


The authors used an individual patient data analysis from 10 randomized trials to assess the modifying effects of bodyweight and height on the effects of low doses (≤100 mg) and higher doses (300-325 mg or ≥500 mg) of aspirin for primary prevention of cardiovascular events. They also analyzed the effects of weight or height on aspirin dose for prevention of colorectal cancer.


The 10 eligible trials included 117,279 patients. Bodyweight varied from median 60-81.2 kg (132-179 lbs). The ability for 75-100 mg of aspirin to reduce cardiovascular events decreased with increasing weight (p interaction = 0.0072). Benefit was seen in patients weighing 50-69 kg (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.65-0.85), but not in patients weighing 70 kg or more (HR, 0.95; 95% CI, 0.86-1.04). Higher doses of aspirin (≥325 mg) reduced cardiovascular events only at higher weight (pinteraction = 0.017). Aspirin-mediated reduction in long-term risk of colorectal cancer was weight-dependent (pinteraction = 0.038).


The benefits of aspirin to prevent cardiovascular events appear to be dose-dependent, with increasing bodyweight requiring higher aspirin doses.


This meta-analysis of primary prevention studies suggests that a one-size-fits-all approach to aspirin therapy may not be ideal. These data are important in light of the ongoing ADAPTABLE study (NCT02697916) comparing the use of low- and standard-dose aspirin for the prevention of cardiovascular events in at-risk patients. Ongoing studies of low-dose aspirin for primary prevention are ongoing and will shed more light onto these findings. Additionally, clinicians should be careful not to extend these findings to the use of aspirin for secondary prevention of cardiovascular events until those studies are undertaken.

Clinical Topics: Prevention

Keywords: Aspirin, Body Height, Body Weight, Colorectal Neoplasms, Primary Prevention, Secondary Prevention, Risk, Stroke, Vascular Diseases, Weight Gain

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