DOAC score among patients receiving Vitamin K antagonists

The direct acting oral anticoagulant (DOAC) score is a bleeding risk score that incorporates 10 common clinical variables to risk stratify major bleeding in patients with atrial fibrillation and demonstrated improved risk stratification compared with HAS-BLED in patients receiving DOACs. This study evaluates the discriminative performance of the DOAC score among patients taking vitamin K antagonists (VKAs).

Data were obtained from COMBINE-AF and GARFIELD-AF. COMBINE-AF included patients with atrial fibrillation randomized to warfarin from 4 clinical trials: RE-LY, ARISTOTLE, ROCKET-AF, and ENGAGE AF-TIMI 48. GARFIELD-AF included patients with atrial fibrillation prescribed VKAs in a registry. The DOAC score of each patient was determined, based on commonly obtained clinical variables. Patients were then stratified by DOAC score clinical risk categories (very low [score: 0-3], low [score: 4-5], moderate [score: 6-7], high [score: 8-9], and very high [score: 10]), and the rate of major bleeding at 1 year was compared between groups. Discrimination was assessed using C-statistics and compared with HAS-BLED using DeLong's test.

A total of 28,818 patients in COMBINE-AF and 20,183 patients in GARFIELD-AF receiving vitamin K antagonists were included. Of these individuals, 994 (3.4%) in COMBINE-AF and 313 (1.6%) in GARFIELD-AF experienced a major bleeding event at 1 year. Patients in higher DOAC score risk categories experienced greater 1-year major bleeding rates in COMBINE-AF, including very low (1.8 events per 100 person-years [events/100p-y]), low (3.0 events/100 p-y), moderate (4.6 events/100 p-y), high (5.6 events/100 p-y), and very high (7.9 events/100 p-y). Discrimination in COMBINE-AF was moderate and higher than HAS-BLED at 1 year (C-statistic: 0.62 vs 0.59, P < .001). In GARFIELD-AF, higher risk categories also had higher 1-year major bleeding rates: very low (0.8 events per 100 person-years [events/100 p-y]), low (1.5 events/100 p-y), moderate (2.2 events/100 p-y), high (3.2 events/100 p-y), and very high (7.6 events/100 p-y). Discrimination in GARFIELD-AF was moderate and higher than the HAS-BLED score at 1 year (C-statistic: 0.65 vs 0.62, P < .001).

In patients with atrial fibrillation taking VKAs, the DOAC score was able to risk stratify patients based on bleeding risk, had moderate discrimination, and out-performed the HAS-BLED score in both a pooled clinical trials cohort and a usual care registry.