Risk of Stroke Outcomes in Atrial Fibrillation Patients Treated with Rivaroxaban and Warfarin.

OBJECTIVES: In a previous real-world study, rivaroxaban reduced the risk of stroke overall and severe stroke compared with warfarin in patients with nonvalvular atrial fibrillation (NVAF). The aim of this study was to assess the reproducibility in a different database of our previously observed results (Alberts M, et al. Stroke. 2020;51:549-555) on the risk of severe stroke among NVAF patients in a different population treated with rivaroxaban or warfarin. MATERIAL AND METHODS: This retrospective cohort study included patients from the IBM® MarketScan® Commercial and Medicare databases (2011-2019) who initiated rivaroxaban or warfarin after a diagnosis of NVAF, had ≥6 months of continuous health plan enrollment, had a CHA2DS2-VASc score ≥2, and had no history of stroke or anticoagulant use. Patient data were assessed until the earliest occurrence of a primary inpatient diagnosis of stroke, death, end of health plan enrollment, or end of study. Stroke severity was defined by National Institutes of Health Stroke Scale (NIHSS) score, imputed by random forest model. Cox proportional hazard regression was used to compare risk of stroke between cohorts, balanced by inverse probability of treatment weighting. RESULTS: The mean observation period from index date to either stroke, or end of eligibility or end of data was 28 months. Data from 13,599 rivaroxaban and 39,861 warfarin patients were included. Stroke occurred in 272 rivaroxaban-treated patients (0.97/100 person-years [PY]) and 1,303 warfarin-treated patients (1.32/100 PY). Rivaroxaban patients had lower risk for stroke overall (hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.76-0.88) and for minor (NIHSS 1 to <5; HR, 0.83; 95% CI, 0.74-0.93), moderate (NIHSS 5 to <16; HR, 0.88; 95% CI, 0.78-0.99), and severe stroke (NIHSS 16 to 42; HR, 0.44; 95% CI, 0.22-0.91). CONCLUSIONS: The results of this study in a larger population of NVAF patients align with previous real-world findings and the ROCKET-AF trial by showing improved stroke prevention with rivaroxaban versus warfarin across all stroke severities.

Healthcare costs before and after stroke in patients with non-valvular atrial fibrillation who initiated treatment with rivaroxaban or warfarin.

AIMS: Rivaroxaban reduces stroke compared with warfarin in patients with non-valvular atrial fibrillation (NVAF). This study compared healthcare costs before and after stroke in NVAF patients treated with rivaroxaban or warfarin. MATERIALS AND METHODS: Using de-identified IBM MarketScan Commercial and Medicare databases, this retrospective cohort study (from 2011 to 2019) included patients with NVAF who initiated rivaroxaban or warfarin within 30 days after initial NVAF diagnosis. Patients who developed stroke were identified, and stroke severity was determined by the National Institutes of Health Stroke Scale (NIHSS) score, imputed by a random forest method. Total all-cause per-patient per-year (PPPY) costs of care were determined for patients: (1) who developed stroke during the pre- and post-stroke periods and (2) who remained stroke-free during the follow-up period. Treatment groups were balanced using inverse probability of treatment weighting. RESULTS: A total of 13,599 patients initiated rivaroxaban and 39,861 initiated warfarin, of which 272 (2.0%) and 1,303 (3.3%), respectively, developed stroke during a mean follow-up of 28 months. Among patients who developed stroke, PPPY costs increased from the pre-stroke to post-stroke period, with greater increases in the warfarin cohort relative to the rivaroxaban cohort. Overall, the costs increased by 1.78-fold for rivaroxaban vs 3.07-fold for warfarin; for less severe strokes (NIHSS < 5), costs increased 0.88-fold and 1.05-fold, respectively. Cost increases for more severe strokes (NIHSS ≥ 5) among rivaroxaban patients were half those for warfarin patients (3.19-fold vs 6.37-fold, respectively). Among patients without stroke, costs were similar during the follow-up period between the two treatment groups. CONCLUSIONS: Total all-cause costs of care increased in the post-stroke period, and particularly in the patients treated with warfarin relative to those treated with rivaroxaban. The lower rate of stroke in the rivaroxaban cohort suggests that greater pre- to post-stroke cost increases result from more strokes occurring in the warfarin cohort.