The efficacy and safety of lower-dose aspirin for primary and secondary prevention of cardiovascular disease in the elderly: an interim analysis of a multicenter, prospective, observational study

Introduction Although low-dose aspirin effectively reduces atherothrombosis occurrence in individuals diagnosed with cardiovascular disease (CVD) or in those with high-risk factors, it is significantly associated with increased bleeding. No evidence has been established for a lower dose of aspirin. Methods The Lower-dose Aspirin for Primary and Secondary Prevention of Cardiovascular Disease in the Elderly (LAPIS) is a multicenter, prospective, observational cohort study, which compared the benefits and risks in adults aged 60 years and older taking aspirin 50 or 100 mg/day for primary and secondary CVD prevention in a propensity score-matched population. The efficacy outcome was a composite of the first occurrence of major adverse cardiovascular events (MACE). The safety outcome was the first occurrence of any hemorrhagic events. Results In this interim analysis of LAPIS, 7,021 participants were followed up for a median of 183 (95% CI 169–197) days (primary prevention cohort, 2,070; secondary prevention cohort, 4,951). After adjusting for baseline characteristics using propensity score matching, the MACE incidence did not differ significantly between the two dosage groups in either cohort. However, in the primary prevention cohort, the incidence of any bleeding [8.89 vs. 3.45 events/100 patient-years, hazard ratio (HR) 2.917, 95% confidence interval (CI) 1.719–4.952, P < 0.001] and gastrointestinal events (8.30 vs. 5.04 events/100 patient-years, HR 1.745, 95% CI 1.047–2.907, P = 0.037) was higher in the 100 mg/day group. In the secondary prevention cohort, the 100 mg/day group showed higher rates of any bleeding (9.19 vs. 6.37 events/100 patient-years, HR 1.473, 95% CI 1.087–1.998, P = 0.015), minor bleeding (9.10 vs. 6.06 events/100 patient-years, HR 1.541, 95% CI 1.116–2.127, P = 0.009), and gastrointestinal adverse events (7.10 vs. 3.53 events/100 patient-years, HR 1.943, 95% CI 1.291–2.925, P = 0.002). Conclusion Aspirin 50 mg/day was associated with lower hemorrhage and gastrointestinal adverse event risks, with similar cardiovascular benefits, compared with aspirin 100 mg/day, and may be preferred to balance efficacy and safety for older Chinese adults in primary and secondary CVD prevention.