Aspirin Discontinuation and Cardiovascular Risk

Study Questions:

What are the associations of aspirin treatment persistence patterns and aspirin discontinuation on risk of cardiovascular events?

Methods:

The investigators performed a cohort study of 601,527 users of low-dose aspirin for primary or secondary prevention in the Swedish prescription register between 2005 and 2009, who were >40 years of age, were free from previous cancer, and had ≥80% adherence during the first observed year of treatment. Cardiovascular events were identified with the Swedish inpatient and cause-of-death registers. The first 3 months after a major bleeding or surgical procedure were excluded from the time at risk. Absolute risks of events were illustrated with Nelson-Aalen cumulative incidence plots, which were also used to assess proportionality of hazards.

Results:

During a median of 3.0 years of follow-up, 62,690 cardiovascular events occurred. Patients who discontinued aspirin had a higher rate of cardiovascular events than those who continued (multivariable-adjusted hazard ratio, 1.37; 95% confidence interval, 1.34-1.41), corresponding to an additional cardiovascular event observed per year in 1 of every 74 patients who discontinue aspirin. The risk increased shortly after discontinuation and did not appear to diminish over time.

Conclusions:

The authors concluded that among long-term users, discontinuation of low-dose aspirin in the absence of major surgery or bleeding was associated with a >30% increased risk of cardiovascular events.

Perspective:

This large nationwide patient cohort reports that discontinuation of long-term low-dose aspirin was associated with a >30% higher risk of cardiovascular events, corresponding to an additional cardiovascular event observed per year in 1 of every 74 patients who discontinue aspirin. The risk appears to increase as soon as the patients discontinued aspirin, with no safe interval. Furthermore, aspirin discontinuation appears especially hazardous among patients with previous cardiovascular disease, with an additional cardiovascular event per year in 1 of every 36 secondary prevention patients compared with an additional cardiovascular event per year in 1 of every 146 primary prevention patients who discontinued aspirin. Policymakers and physicians should focus on adherence to low-dose aspirin treatment in the absence of major surgery or bleeding as an important treatment goal.

Clinical Topics: Prevention

Keywords: Aspirin, Cardiovascular Diseases, Hemorrhage, Myocardial Ischemia, Neoplasms, Patient Compliance, Primary Prevention, Risk, Secondary Prevention, Surgical Procedures, Operative


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