CHA2DS2-VASc Score, Warfarin Use, and Risk for Thromboembolic Events Among HIV-Infected Persons With Atrial Fibrillation.

Abstract

The prevalence of atrial fibrillation in the HIV-infected population is growing, but the ability of the CHA2DS2-VASc score to predict thromboembolic (TE) risk is unknown in this population. Within the Veterans Affairs HIV Clinical Case Registry, 914 patients had an atrial fibrillation diagnosis between 1997 and 2011 and no previous TE events. We compared TE incidence by CHA2DS2-VASc scores and stratified by warfarin use. Using Cox proportional hazards regression with adjustment for competing risks, we modeled associations of CHA2DS2-VASc scores and warfarin use with TE risk. At baseline, the distribution of CHA2DS2-VASc scores was 0 (n = 208), 1 (n = 285), and 2+ (n = 421); 34 patients developed 38 TE events during a median of 3.8 years follow-up. Event rates by CHA2DS2-VASc scores of 0, 1, and 2+ were 5.4, 9.3, and 8.1 per 1000 person years, respectively; multivariate-adjusted hazards ratios (HRs) were 1.70 (95% confidence interval: 0.65 to 4.45) for CHA2DS2-VASc score 1 (P = 0.28) and HR = 1.34 (0.51, 3.48) for score 2+ versus 0 (P = 0.55). Baseline warfarin use was associated with increased TE risk, although not statistically significant [HR 2.06 (0.86, 4.93), P = 0.11] with similar results when modeled as time-updated use and duration of use. In this national registry of HIV-infected veterans with atrial fibrillation, CHA2DS2-VASc scores were only weakly associated with TE risk. Furthermore, warfarin did not seem to be effective at preventing TE events. These results should raise concerns about the optimal strategy for TE prevention among HIV-infected persons with atrial fibrillation.