Number needed to treat for net clinical benefit of oral anticoagulants in Asian patients with atrial fibrillation

Background

Oral anticoagulants (OAC) can reduce ischemic stroke/systemic embolism (SSE) in patients with non-valvular atrial fibrillation (AF) while increasing the risk of major bleeding. We aimed to analyze the number needed to treat for the net benefit (NNTnet) of warfarin and non-vitamin K antagonist oral anticoagulants (NOACs).

Methods

We analyzed the results from multicenter national AF registry from 27 hospitals in Thailand. Follow-up data were collected every 6 months until 3 years. Main outcomes were SSE, major bleeding, and intracranial hemorrhage (ICH). NNT was calculated from the absolute risk reduction (ARR) of SSE or absolute risk increase (ARI) of major bleeding or ICH. We compared NNTnet of warfarin versus no OAC, NOACs versus no OAC, and NOACs versus warfarin. Warfarin was also categorized into time in therapeutic range (TTR) < and ≥65%.

Results

We studied a total of 3405 patients (mean age 67.8 ± 11.3 years, 1424 (41.8%) were female). The incidence rates of SSE, major bleeding, and ICH were 1.51, 2.25, and 0.78 per 100 person-years, respectively. Warfarin had negative NNTnet −37 compared to no OAC. NOACs had positive NNTnet 101 and 27 compared to no OACs and warfarin. Warfarin with TTR 65% had positive NNTnet 42 compared to no OAC. NOACs had comparable NNTnet as warfarin with TTR ≥65%.

Conclusion

Warfarin had a negative NNTnet compared to no OAC. Only warfarin with TTR 65% has positive NNTnet. NOACs had positive NNTnet compared to no OAC and when compared to warfarin.