Low doses of aspirin were only effective in preventing vascular events in patients weighing <70 kg, a recent study found. Researchers used individual patient data to analyze the modifying effects of bodyweight and height on the effects on low doses (≤100 mg) and higher doses (300‒325 mg or ≥500 mg) of aspirin in randomized trials of aspirin in primary prevention of cardiovascular (CV) events. They found:
- Low doses of aspirin (75‒100 mg) were only effective in preventing vascular events in patients weighing <70 kg.
- There was no benefit in 80% of men and nearly half of all women weighing ≥70 kg.
- Conversely, higher doses of aspirin were only effective in patients weighing ≥70 kg.
- Findings were similar in men and women, in people with diabetes, in trials of aspirin in secondary prevention, and in relation to height.
- Aspirin-mediated reductions in long-term risk of colorectal cancer were also weight dependent.
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 ahead of print July 12, 2018]. Lancet. doi:10.1016/S0140-6736(18)31133-4.