Low-Dose Aspirin for Primary Prevention of Cardiovascular Events in Elderly Japanese Patients with Atherosclerotic Risk Factors: Subanalysis of a Randomized Clinical Trial (JPPP-70).

INTRODUCTION

This post hoc subanalysis of the randomized Japanese Primary Prevention Project investigated whether once-daily low-dose aspirin versus no aspirin reduced the risk of cardiovascular events (CVEs) in patients aged ≥ 70 years with atherosclerotic risk factors.

METHODS

Patients aged < 70 years (young-old) or ≥ 70 years (old) with hypertension, dyslipidemia, or diabetes participated between 2005 and 2007. Patients were randomized 1:1 to receive 100 mg enteric-coated aspirin once daily or no aspirin plus standard of care. The primary outcome was a composite of death from cardiovascular causes plus nonfatal stroke and nonfatal myocardial infarction. The secondary outcome was a composite of the primary outcome plus transient ischemic attack, angina pectoris, and arteriosclerotic disease requiring medical or surgical intervention. Old (n = 7971) and young-old (n = 6493) patients were followed up for a median 5.02 years.

RESULTS

Aspirin did not reduce the risk of primary (hazard ratio [HR] 0.92 [95% confidence interval {CI} 0.74-1.16]; P = 0.50) or secondary (0.85 [0.70-1.04]; P = 0.11) outcomes in patients aged ≥ 70 years. In old men with high-density lipoprotein < 40 mg/dL, treatment with low-dose aspirin was associated with a reduction in the incidence of the primary endpoint compared with the group not receiving aspirin (10/260 vs 22/250; HR 0.44 [95% CI 0.20-0.93]; P = 0.03). This subgroup was also found to contain significant larger proportions of patients with elevated body mass index, patients with diabetes mellitus, and smokers (P < 0.001). Old patients also showed differences in bleeding outcomes. Serious extracranial hemorrhage requiring transfusion or hospitalization occurred significantly more frequently in the aspirin-treated group than in the non-aspirin-treated group (35 [0.88%] vs 18 [0.45%]; HR 1.96 [1.11-3.46]; P = 0.020). Gastrointestinal hemorrhage occurred significantly more frequently in the aspirin-treated group than the non-aspirin-treated group (63 [1.58%] vs 18 [0.45%]; relative risk [RR] 3.5 [2.08-5.90]; P < 0.0001). Cerebral hemorrhage (intracranial hemorrhage) tended to occur more frequently in the aspirin-treated group than the non-aspirin-treated group (22 [0.55%] vs 11 [0.28%]; RR 2.01 [0.97-4.14]; P = 0.058). Cerebral hemorrhage occurred significantly more frequently in old patients than in young-old patients (33 [0.41%] vs 10 [0.15%]; HR 2.7 [1.34-5.53]; P = 0.0055). Gastrointestinal hemorrhage occurred in a slightly higher proportion of old patients compared with young-old patients (81 [1.02%] vs 53 [0.82%]; RR 1.2 [0.88-1.76]; P = 0.21).

DISCUSSION/CONCLUSIONS: Aspirin did not reduce the risk of the primary or secondary outcomes in old patients. Aspirin treatment may have reduced CVEs within a high CVE risk elderly population subgroup. Aspirin treatment in such a group requires caution, because of the increased risk of intracranial hemorrhage, severe extracranial hemorrhage requiring hospitalization or transfusion, and gastrointestinal bleeding in old patients receiving aspirin therapy.

CLINICAL TRIAL REGISTRATION

The study is registered at ClinicalTrials.gov [NCT00225849].