Abstract 17202: Comparative Performance of the R 2 Chads 2 , Chads 2 , and Cha 2 Ds 2 -vasc Scores in Atrial Fibrillation

Abstract

Background . Existing scores to estimate stroke risk in atrial fibrillation (AF) have shown variable performance. We compared the predictive performance of the R 2 CHADS 2 score, which includes a term for renal dysfunction, to that of two existing stroke risk scores, CHADS 2 and CHA 2 DS 2 -VASc. Methods . We used data from the ORBIT-AF study, a national, prospective, outpatient registry of incident and prevalent AF in patients >18 years. We examined the association between impaired renal function (CrCl<60 mL/min) and 2-year risk of stroke/systemic embolism (SE) in separate Cox proportional hazards models with linear terms for CHADS 2 and CHA 2 DS 2 -VASc scores. We compared discrimination of the three scores using c-indices and evaluated calibration of R 2 CHADS 2 by comparing event rates in ORBIT to published rates from an external clinical trial population (ROCKET-AF) and an observational cohort (ATRIA). Results . We included N=9743 patients enrolled at 174 ORBIT-AF sites. The median age was 75 years (IQR 67-82), 89.5% were white, 42.5% were female, and 76.4% were taking oral anticoagulation (OAC). Over a median follow-up of 2 years, N=214 stroke/systemic embolism (SE) events occurred (1.00 per 100 pt.-years). Impaired renal function was present in 35.4% of patients and was associated (HR; 95% CI) with increased stroke/SE risk in unadjusted models (1.65; 1.27-2.14). This association was attenuated in models adjusting for CHADS 2 (1.21; 0.92, 1.60) or CHA 2 DS 2 -VASc (1.05; 0.79, 1.40). Discrimination (c-index; 95% CI) was similar for R 2 CHADS 2 , CHADS 2 and CHA 2 DS 2 -VASc; results were consistent by baseline OAC use (Table). Stroke/SE event rates in ORBIT were lower than those in two external populations for all levels of R 2 CHADS 2 . Conclusion: In a well-treated community patient population, renal dysfunction did not improve discrimination of traditional embolic risk models. Future studies examining the association between renal dysfunction and outcomes by type of OAC are needed.