In older adults taking aspirin to prevent a first heart attack or stroke, those taking 50 mg per day have less than one-third the rate of bleeding compared to those taking 100 mg per day.
Evidence from Studies
No evidence studies found yet.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
A systematic review of RCTs would determine whether the 2.9-fold reduction in bleeding with 50 mg versus 100 mg aspirin is consistent across diverse populations and not an artifact of observational bias.
A systematic review and meta-analysis of all randomized trials comparing 50 mg and 100 mg aspirin in adults aged 60+ without prior CVD, including at least 8,000 participants with 2-year follow-up, measuring any bleeding (BARC ≥1) as primary endpoint, with subgroup analysis by sex, renal function, and concomitant NSAID use.
A randomized trial would determine whether assigning older adults to 50 mg versus 100 mg aspirin directly causes a 2.9-fold reduction in bleeding risk in primary prevention.
A double-blind RCT of 3,000 adults aged 60–85 with cardiovascular risk factors but no prior CVD, randomized 1:1 to 50 mg or 100 mg aspirin daily for 3 years, with primary endpoint of any bleeding (BARC ≥1), secondary endpoints of major bleeding and gastrointestinal events, and mandatory annual lab and medication adherence checks.
A longer-term cohort with more complete follow-up could confirm whether the 2.9-fold bleeding difference persists beyond the current 183-day median follow-up.
A prospective cohort of 8,000 older Chinese adults without prior CVD initiating aspirin therapy, with annual dose recording, bleeding event adjudication by independent reviewers, and adjustment for time-varying confounders such as anticoagulant initiation or renal decline over 5 years.
A case-control study could assess whether prior exposure to 100 mg aspirin is more common among those who experienced bleeding than among matched controls without bleeding.
A nested case-control study within the LAPIS cohort comparing 150 patients with any bleeding event to 300 matched controls without bleeding, assessing prior aspirin dose, duration, and concomitant medications, with exposure data collected prospectively and blinded to outcome.
A cross-sectional survey could estimate the prevalence of bleeding symptoms among older adults currently taking 50 mg versus 100 mg aspirin, but cannot determine whether dose caused the bleeding.
A national survey of 10,000 older Chinese adults taking aspirin for primary prevention, collecting self-reported bleeding symptoms and current aspirin dose via structured interviews and pharmacy records, with validation of aspirin use via blood salicylate levels in a subsample.