An analysis adjusted for age, sex, index event (deep vein thrombosis or pulmonary embolism), and duration of initial anticoagulation treatment confirmed that aspirin reduced the risk of recurrence (adjusted HR=0.53; 95% CI, 0.32-0.85; P=.009). No association was found between recurrent VTE and duration of anticoagulation therapy (6 months vs longer). Nor was there a difference in recurrence rates based on the index event.
WHAT’S NEW: Aspirin has a key role in preventing recurrence
This study found that for patients with unprovoked VTE who completed a course of oral anticoagulation, aspirin was effective in preventing a recurrence, with no apparent increase in the risk of major bleeding. Protection in Year 2 was nearly as great as in Year one.1
CAVEAT: Patients were followed for just 2 years
It is unclear whether continuing aspirin therapy beyond 2 years would continue to confer protection against a VTE recurrence without an increase in adverse effects.
CHALLENGE TO IMPLEMENTATION: Some patients can’t tolerate chronic aspirin therapy
Although this study investigated aspirin in a dosage of 100 mg/d, this strength is not readily available in the United States.4 There is no evidence to suggest that the 81-mg strength that is available in this country would provide a diminished antiplatelet effect. And, as is already customary, patients undergoing chronic aspirin therapy must be monitored for major bleeding, GI irritation, and renal compromise. A few patients will be ineligible for prophylaxis due to a history of intolerance to aspirin or nonsteroidal anti-inflammatory drugs.
Acknowledgement
The PURLs Surveillance System was supported in part by Grant Number UL1RR024999 from the National Center for Research Resources, a Clinical Translational Science Award to the University of Chicago. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources or the National Institutes of Health.
