Aspirin for CVD Prevention: Does One Dose Fit All?

Low-dose aspirin does not help to prevent cardiovascular events in men and women weighing more than 70 kg (~154 lbs), according to the results of a recent study.

Currently, the one-dose-fits-all approach to aspirin use has yielded “only modest benefits in long-term prevention of cardiovascular events,” according to the study’s authors. Underdosing in larger patients and excess dosing in smaller patients could explain these results.

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Using data from 10 eligible trials of aspirin in primary prevention (N=117,279) the researchers sought to determine the impact of bodyweight and height on the effects of low doses (≤100 mg) and higher doses (300–325 mg or ≥500 mg) of aspirin.

Overall, median bodyweight ranged from 60.0 kg to 81.2 kg. The researchers observed that the ability of 75-100 mg aspirin to reduce cardiovascular events decreased with increasing weight, showing benefits in individuals weighing 50-69 kg (hazard ratio [HR] 0.75) but not in those weighing 70 kg or more (odds ratio 1.33).

Higher doses, however, had the opposite interaction with bodyweight, reducing risk only in those of higher weight. Results were similar among men and women, and in relation to height. Aspirin-related reductions in colorectal cancer risk were also weight dependent.

Further, risks related to excess dosing were revealed following stratification by body size, with risk of sudden death increased by aspirin in individuals at low weight for dose and risk of all-cause death increased in individuals weighing less than 50 kg receiving 75-100 mg aspirin (HR 1.52). In participants aged 70 years and older, 3-year cancer risk was increased by aspiring, particularly in those weighing less than 70 kg.

“Low doses of aspirin (75–100 mg) were only effective in preventing vascular events in patients weighing less than 70 kg and had no benefit in the 80% of men and nearly 50% of all women weighing 70 kg or more. By contrast, higher doses of aspirin were only effective in patients weighing 70 kg or more. Given that aspirin's effects on other outcomes, including cancer, also showed interactions with body size, a one-dose-fits-all approach to aspirin is unlikely to be optimal, and a more tailored strategy is required.”

—Michael Potts

Reference:

Rothwell PM, Cook NR, Gaziano JM, et al. Effects of aspirin on risks of vascular events and cancer according to bodyweight and dose: analysis of individual patient data from randomised trials [published online July 12, 2018]. Lancet. https://doi.org/10.1016/S0140-6736(18)31133-4