Do most patients need higher-dose aspirin to prevent vascular events?
Low-dose aspirin is ineffective for most people taking it to help prevent vascular events, a Lancet analysis of 120,000 people reveals.
For those weighing more than 70kg (which is 80% of men and nearly 50% of women), low-dose (75-100mg) aspirin is unlikely to do much good.
Instead, these patients require higher doses (300-325mg or 500mg), the researchers found, especially those who smoke or take enteric-coated aspirin.
Conversely, lighter people can expect to still benefit from low-doses of aspirin, the researchers say.
The findings were consistent for daily and alternate-day dosing.
A one-dose-fits-all approach to aspirin is not recommended, they say.
“Loss of efficacy can occur if the aspirin dose is too low or too high for body size, and other harms appear to result from excess dosing,” writes the University of Oxford’s Professor Peter Rothwell and colleagues.
Reductions in cardiovascular events and all-cause death at optimal doses for weight were “substantial”, highlighting the potential of more tailored aspirin dosing, they said.
In a linked commentary, US researchers described the results as “provocative”, with the potential to substantially affect public health.
Heavier people might have more esterases, which actively clear aspirin from the body, they said.
“It seems plausible that individuals with a larger body mass would have a greater quantity of these esterases than would smaller individuals, resulting in reduced aspirin bioavailability,” they wrote.