A large landmark study found that low-dose and regular-strength aspirin is equally safe and effective for preventing additional heart problems in people who already have heart disease, writes MedicalBrief.
The ADAPTABLE trial was unusual in that it patients enrolled themselves and tracked their health online while taking the 81-mg dose or the 325-mg dose, as it pleased them.
People had such a strong preference for the lower dose that it’s unclear if the results can establish that the treatments are truly equivalent, some independent experts are quoted as saying in an Associated Press report. Half who were told to take the higher dose took the lower one instead or quit using aspirin altogether.
About 15,000 people received invitations to join through the mail, email or a phone call and enrolled on a website where they returned every three to six months for follow-up. A network of participating health centers supplied medical information on participants from their electronic records and insurance claims.
The participants were randomly assigned to take low- or regular-dose aspirin, which they bought over the counter. Nearly all were taking aspirin before the study began and 85% were already on a low dose, so “it was an uphill task right from the get-go” to get people to use the dose they were told, AP reports.
After roughly two years, about 7% of each group had died or been hospitalised for a heart attack or a stroke. Safety results also were similar — less than 1% had major bleeding requiring hospitalisation and a transfusion.
Nearly 41% of those assigned to take the higher dose switched at some point to the lower one, and that high rate “could have obscured a true difference” in safety or effectiveness, Colin Baigent, a medical scientist at the University of Oxford, wrote in a commentary in the New England Journal of Medicine.
One study leader, Dr Schuyler Jones of Duke University, said the study still provides valuable guidance. If patients are taking low-dose aspirin now, “staying on that dose instead of switching is the right choice,” he said. People doing well on 325 milligrams now may want to continue on that and should talk with their doctors if they have any concerns.
For new patients, “in general, we’re going to recommend starting the low dose,” Jones said.
Study details
Comparative Effectiveness of Aspirin Dosing in Cardiovascular Disease
Authors: W. Schuyler Jones, M.D., Hillary Mulder, M.S., Lisa M. Wruck, Ph.D., Michael J. Pencina, Ph.D., Sunil Kripalani, M.D., Daniel Muñoz, M.D., David L. Crenshaw, L.M.S.W., Mark B. Effron, M.D., Richard N. Re, M.D., Kamal Gupta, M.D., R. David Anderson, M.D., Carl J. Pepine, M.D., et al., for the ADAPTABLE Team
Published 11 May in the New England Journal of Medicine
Abstract
BACKGROUND
The appropriate dose of aspirin to lower the risk of death, myocardial infarction, and stroke and to minimize major bleeding in patients with established atherosclerotic cardiovascular disease is a subject of controversy.
METHODS
Using an open-label, pragmatic design, we randomly assigned patients with established atherosclerotic cardiovascular disease to a strategy of 81 mg or 325 mg of aspirin per day. The primary effectiveness outcome was a composite of death from any cause, hospitalisation for myocardial infarction, or hospitalisation for stroke, assessed in a time-to-event analysis. The primary safety outcome was hospitalisation for major bleeding, also assessed in a time-to-event analysis.
RESULTS
A total of 15,076 patients were followed for a median of 26.2 months (interquartile range [IQR], 19.0 to 34.9). Before randomisation, 13,537 (96.0% of those with available information on previous aspirin use) were already taking aspirin, and 85.3% of these patients were previously taking 81 mg of daily aspirin. Death, hospitalisation for myocardial infarction, or hospitalisation for stroke occurred in 590 patients (estimated percentage, 7.28%) in the 81-mg group and 569 patients (estimated percentage, 7.51%) in the 325-mg group (hazard ratio, 1.02; 95% confidence interval [CI], 0.91 to 1.14).
Hospitalisation for major bleeding occurred in 53 patients (estimated percentage, 0.63%) in the 81-mg group and 44 patients (estimated percentage, 0.60%) in the 325-mg group (hazard ratio, 1.18; 95% CI, 0.79 to 1.77). Patients assigned to 325 mg had a higher incidence of dose switching than those assigned to 81 mg (41.6% vs. 7.1%) and fewer median days of exposure to the assigned dose (434 days [IQR, 139 to 737] vs. 650 days [IQR, 415 to 922]).
CONCLUSIONS
In this pragmatic trial involving patients with established cardiovascular disease, there was substantial dose switching to 81 mg of daily aspirin and no significant differences in cardiovascular events or major bleeding between patients assigned to 81 mg and those assigned to 325 mg of aspirin daily.
Full study in NEJM (Open access)
Aspirin use for CVD may reduce risk of COVID-19 infection – Israeli study
See also from the MedicalBrief archives:
Aspirin use for CVD may reduce risk of COVID-19 infection – Israeli study
Pre-diagnosis aspirin use may lower colorectal cancer mortality — American Cancer Society
Polypill plus aspirin reduces incidence of cardiovascular events by 31% — TIPS-3
Aspirin use significantly reduces ICU admission and risk of death from COVID-19 — Hospital study
Regular aspirin to reduce bowel cancer risks lasts at least 10 years after stopping Tx