San Francisco—Pharmacists may want to raise some concerns when older patients with a myriad of health problems continue to use anticoagulants for atrial fibrillation (AF).

The problem, according to a report in Circulation: Cardiovascular Quality and Outcomes, is that the benefits of those drugs decrease with age. University of California San Francisco researchers suggest that the risk of death from other factors begins to outweigh any positive effects of the medications.

Specifically, the study, which was presented at the annual American Heart Association Scientific Sessions 2019 in Philadelphia, determined that the anticoagulant warfarin was not beneficial after age 87 years and a direct-acting oral anticoagulant, apixaban, lost benefit after age 92 years.

The multi-institutional study involved nearly 15,000 AF patients, and, in light of their findings, the authors recommend that all mortality risks, such as cancer and end-stage kidney disease, be considered before recommending anticoagulants to older AF patients.

“Many prior studies looking at the benefit of blood thinners found older adults benefit more than younger adults, but they narrowly focus on atrial fibrillation and strokes and don't account for all other health conditions affecting older adults,” said lead author Sachin Shah, MD, MPH, assistant professor of medicine at UCSF. “Our study is the first to find that when taking these factors into consideration, anticoagulant benefit actually decreases with age.”

Background information in the report notes that guidelines recommend anticoagulation for all AF patients aged 75 years and older, even though evidence for the net clinical benefit (NCB) of anticoagulant in older adults is limited.

To determine the association between age and NCB of anticoagulation in older adults with AF, researchers focused on patients with the condition who were aged 75 years and older, using the Anticoagulation and Risk Factors in Atrial Fibrillation—Cardiovascular Research Network cohort. The study team estimated the lifetime NCB of warfarin and apixaban relative to no treatment in quality-adjusted life years (QALYs).

In the decision model, the patients—who had a median age of 81 years and a median CHADS-VASc score of 4—were assumed to face a chance of stroke, hemorrhage, or death from a competing cause each month, based on their individual factors. Minimal clinically relevant lifetime benefit was defined as 0.10 QALYs.

“In the main analysis, after age 87, NCB associated with warfarin decreased below 0.10 lifetime QALYs while NCB associated with apixaban did not decrease below 0.10 lifetime QALYs until after age 92,” the researchers report. “In sensitivity analyses, over a 3-year horizon, removing competing risks of death resulted in higher NCB (at 90 years, median difference using warfarin 0.010 QALYs [95% CI, 0.009-0.013], median difference using apixaban 0.025 QALYs [95% CI, 0.024-0.026]).”

The issue, according to the study, is that the risk of ischemic stroke increases with age, but so do risks of anticoagulant-associated bleeding complications and death from other causes, such as cancer.

“Physicians should consider competing mortality risks when recommending anticoagulants to older adults with AF,” the authors conclude.

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