Influence of blood pressure on the effects of low-dose asprin in elderly patients with multiple atherosclerotic risks

OBJECTIVE: We examined whether the efficacy of low-dose acetylsalicylic acid (aspirin) for primary prevention of cardiovascular events is influenced by blood pressure (BP) using data from patients aged 60-85 years with hypertension, dyslipidemia, and/or diabetes, but without cardiovascular disease of the Japanese Primary Prevention Project. METHODS: All patients had received aspirin (100 mg/day) or no aspirin. BP subgroups were defined as low (average SBP from the baseline to the year of the events <130 mmHg), moderate (≥130 and <140 mmHg), and high (≥140 mmHg). The mean duration of follow-up was 5.02 years. RESULTS: In hypertensive patients (n = 12 278) aspirin had no significant impact on the primary outcome of death from cardiovascular disease, nonfatal stroke, and nonfatal myocardial infarction. On the other hand, aspirin increased the incidence of serious extracranial hemorrhage [hazard ratio, 1.81; 95% confidence interval (CI), 1.18-2.77; P = 0.0064] and tended to increase hemorrhagic stroke (hazard ratio, 1.75; CI, 0.99-3.07; P = 0.053). Aspirin had no effect on the primary outcome in any of the BP subgroups, and was associated with increased hemorrhagic stroke in the high BP group (hazard ratio, 3.51; CI, 1.29-9.51; P = 0.014); serious extracranial hemorrhage was elevated or tended to elevate in the moderate (hazard ratio, 2.53; CI, 1.18-5.45; P = 0.017) and high (hazard ratio, 2.14; CI, 1.00-4.56; P = 0.050) BP groups. CONCLUSION: In aged Japanese hypertensive patients, these data demonstrated no overall benefit of low-dose aspirin therapy although treatment was associated with an elevated risk of hemorrhagic events.