Comparable effectiveness of low-dose and regular-strength aspirin in patients with ASCVD

ACC 2021 The ADAPTABLE trial demonstrated similar effectiveness with 81 mg vs. 325 mg of daily aspirin in patients with established ASCVD. Also, major bleeding events were comparable between patients taking low-dose or regular-strength aspirin.

Aspirin Dosing: A Patient-centric Trial Assessing Benefits And Long-term Effectiveness Trial (ADAPTABLE)

Presented at ACC.21 by William Schuyler Jones, MD (Durham, NC, USA)

Aspirin is the most commonly used medication in patients with established atherosclerotic cardiovascular disease (ASCVD) and is associated with lower risk for death, MI, and stroke compared to placebo. However, proper randomized control trial evidence for the optimal dosage of aspirin in these patients is lacking. The main goal of the ADAPTABLE (Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness) study was to determine the effectiveness and safety of 81 mg vs. 325 mg of daily aspirin in patients with ASCVD.

The ADAPTABLE trial was a multicentered, pragmatic designed, randomized, open-label trial that included 15,076 patients from the United States with established ASCVD and one or more additional CVD risk factors. Eligible patients were identified via inclusion/exclusion criteria applied to electronic health records. Patients received an invitation to take part in the study via mail, email or phone call and enrolled and randomized themselves to 81 mg or 325 mg of daily aspirin via the secure website of the study. Participants returned to this website every three to six weeks for follow-up encounters.

The primary effectiveness endpoint was a composite of all-cause mortality, hospitalization for MI, or hospitalization for stroke. The primary safety point was hospitalization for major bleeding that required a blood product transfusion. Median follow-up was 26 months.

Main results

• There were no significant differences in the primary effectiveness endpoint between 81 mg dose group vs. 325 mg dose group (HR 1.02, 95% CI: 0.91-1.14, P=0.75).

• There was also no significant difference in the primary safety endpoint between groups. The primary safety endpoint occurred in 0.63% of patients taking 81 mg of aspirin compared to 0.60% in those on 325 mg of aspirin (HR 1.18, 95% CI: 0.79-1.77).

Conclusion

There were no significant differences in all-cause death, MI, and stroke observed in patients with established ASCVD taking 81 mg vs. 325 mg of daily aspirin. Also, similar low numbers of major bleeding events were observed between the two aspirin groups. However, there was a higher incidence of dose switching in the group of patients on 325 mg of aspirin compared to the group on 81 mg.

Patients with ASCVD who are on 81 mg of aspirin are, based upon the trial outcome, recommended to stay on the low dosage of daily aspirin. When patients are resuming aspirin treatment, initiation with 81 mg of daily aspirin would be best due to better tolerability. Patients who were tolerating the higher dosage (325 mg) of aspirin are recommended to stay on this dose.

Discussion

The discussant Jane Linderbaum (Rochester, MN, USA) commended Schuyler Jones on the design and low-cost of the ADAPTABLE trial in a challenging time period in medicine for both clinicians and patients. The fact that all these patients could be followed virtually probably helped with the ongoing enrollment and participation. The second point that Linderbaum addressed was the 41% of participants that transisioned from the 325 mg daily aspirin group to the 81 mg group. She mentioned that DAPT guidelines and prevention results might have contributed to the dose switching. Linderbaum ended her discussion by saying that health care providers need outcome data that support an aspirin dosage recommendation to patients.

– Our coverage of ACC.21 is based on the information provided during the congress –

The study was simultaneously published in the N Eng J Med. Watch a video by Schuyler Jones on this trial