Comparison of Stroke- and Bleed-Specific Healthcare Resource Utilization and Costs Among Patients with Non-Valvular Atrial Fibrillation, Newly Treated with Dabigatran or Warfarin
Authors: Song Xue , Gandhi Pranav , Gilligan Adrienne M , Arora Prachi , Henriques Caroline , Wang Cheng , Sander Stephen , Smith David M 
Published: October 2019

Abstract
INTRODUCTION: In the pivotal Randomized Evaluation of Long-Term Anticoagulant Therapy (RE-LY) clinical trial, dabigatran was associated with lower rates of stroke and systemic embolism compared to adjusted-dose warfarin. However, real-world evidence comparing stroke- and bleed-specific healthcare resource utilization (HCRU), costs, length of stay (LOS) per hospitalization and readmissions in non-valvular atrial fibrillation (NVAF) patients newly treated with dabigatran or warfarin is limited.
METHODS: Using a nationwide administrative claims database in the US, a retrospective matched-cohort of newly diagnosed NVAF patients aged ≥18 years treated with dabigatran or warfarin in 01/01/2011-12/31/2013 was evaluated. Index date was the first dabigatran or warfarin claim date. All patients had data for 12 months before the index date and a maximum follow-up of 12 months or until discontinuation or switch, disenrollment, end of study period, or inpatient death. Propensity scores were used to match dabigatran and warfarin users 1:1. Stroke or bleed-specific HCRU and costs were defined as hospitalizations with stroke or bleed as the primary discharge diagnosis and outpatient claims with stroke or bleed diagnosis in any position. Percentage and incidence rate (IR) of first stroke or bleed per 100 person-years and associated 95% confidence interval (CI) were reported. Stroke- and bleed-specific per-patient-per-year (PPPY) HCRU and costs were analyzed for all patients. Among those with a hospitalization for stroke or bleed, LOS and readmissions of patients who were admitted and discharged home were reported. Cox regression examined the risk of stroke or bleed and logistic regression assessed the impact on stroke- and bleed-specific readmission between dabigatran and warfarin users.
RESULTS: A total of 18,980 dabigatran patients were matched to corresponding warfarin patients. Of these, the percentage of dabigatran patients with stroke (0.5%, n=87 vs 0.8%, n=142; P<0.001) or bleed (1.2%, n=227 vs 1.6%, n=294; P=0.003) was significantly lower than warfarin patients. The IR (95% CI) of stroke [0.65 (0.51-0.78) vs. 1.06 (0.89-1.24)] and bleed [1.69 (1.47-1.91) vs. 2.20 (1.95-2.46)] was also lower in dabigatran patients compared to warfarin patients. After adjustment, compared to warfarin patients, the hazard ratio (HR) of having a first stroke or bleed was significantly lower in dabigatran patients [(HR = 0.60 (95% CI = 0.46-0.79)) and (HR = 0.76 (95% CI = 0.64-0.91)), respectively].
Among all NVAF patients, dabigatran users had a significantly lower number of stroke-specific hospitalizations (0.007 vs 0.013, P<0.001) and outpatient visits (0.304 vs 0.450, P<0.001) compared to warfarin patients. Similarly, dabigatran users had significantly lower bleed-specific hospitalizations (0.024 vs 0.035, P=0.008) and outpatient visits (0.820 vs 0.920, P=0.018). Dabigatran users had significantly lower stroke-specific outpatient visit costs ($84 vs $144, P=0.01) and bleed-specific hospitalization costs ($360 vs $612, P=0.007). There was no significant difference observed in stroke-specific hospitalization costs and bleed-specific outpatient costs between the two groups.
Among dabigatran patients with a stroke or bleed, average LOS was significantly lower compared to warfarin patients [(4.74 days vs 5.70 days) and (4.30 days vs 4.60 days), both P<0.001]. Stroke-related 30-day readmissions did not significantly differ between dabigatran and warfarin patients (0.4%, n=14 vs 0.6%, n=25, P=0.078). However, the odds of stroke-related readmission were significantly lower in dabigatran compared to warfarin users [Odds Ratio (OR) = 0.59 (95% CI = 0.51-0.69)]. Bleed-related 30-day readmissions were significantly lower for dabigatran than warfarin users (0.8%, n=30 vs. 1.5%, n=59, P=0.002); similar results were found after adjustment [OR=0.54 (95% CI = 0.47-0.63)].
CONCLUSION: Using real-world data of newly diagnosed NVAF patients, dabigatran users had a lower risk of stroke or bleed than warfarin users. Dabigatran users had lower stroke- and bleed-specific HCRU (including LOS per hospitalization), and lower odds of stroke- and bleed-specific readmissions compared to warfarin users. Also, costs associated with bleed-specific hospitalizations and stroke-specific outpatient visits were significantly lower for dabigatran users compared to warfarin users.

Disclosures
Song: Truven Health Analytics: Employment; Amgen: Other: This study was funded by Amgen.. Gilligan:Truven Health Analytics, an IBM Company: Employment. Sander:Boehringer Ingelheim: Employment. Smith:Truven Health Analytics: Employment.