What is the optimal strategy for preventing strokes in adults 80 years and older who have atrial fibrillation?
In this network meta-analysis that included lower-quality studies, the DOACs provided a better balance of benefits (preventing stroke or systemic emboli) and harms (major bleeding) than vitamin K antagonists in adults 80 years or older with atrial fibrillation. The conclusions are comparable with findings from many other analyses of DOACs that have demonstrated fewer harms and comparable benefits.
These authors searched multiple databases to identify studies that reported treatment outcomes of various anticoagulants to prevent stroke and other embolic events in adults with atrial fibrillation who were at least 80 years of age. The authors included 53 studies, 43 of which could be used for meta-analysis and 36 for network meta-analysis. Nine of the studies were randomized trials (12,461 participants) that had between 1 year and 2.8 years of follow-up. The 44 observational studies (383,630 participants) were both retrospective and prospective in nature and had up to 3.3 years of follow-up. The authors don’t report the overall quality of the randomized or observational studies but report quality for the individual comparisons. For apixaban, dabigatran, rivaroxaban, and vitamin K antagonists, the overall quality was decent and for edoxaban and aspirin the overall quality was low. The researchers' main interest was in comparing the direct oral anticoagulants (DOACs) with vitamin K antagonists. The rate of the composite of stroke or systemic emboli was slightly lower with the DOACs than with the vitamin K antagonists. Compared with placebo, the numbers needed to treat for the DOACs ranged from 19 to 22 compared with 23 for vitamin K antagonists. Compared with placebo, the DOACs also caused slightly fewer episodes of major bleeding (the number needed to treat to harm [NNTH] ranged from 7 to 24) than the vitamin K antagonists (NNTH = 9). Although aspirin was no more effective than placebo in preventing stroke or systemic emboli, it caused more major bleeding (NNTH = 9). The authors estimate that the net clinical benefit — a balance between benefits and harms — favored the DOACs in general, and that edoxaban and apixaban had the best profiles. The inclusion of observational studies and the low-quality data for edoxaban likely overestimates its true effectiveness.
Henry C. Barry, MD, MS
Michigan State University
East Lansing, MI