Health care resource utilization and costs among newly diagnosed and oral anticoagulant-naive nonvalvular atrial fibrillation patients treated with dabigatran or warfarin in the United States

Abstract

BACKGROUND: Warfarin has a long history of use to reduce the risk of stroke in patients with atrial fibrillation (AF), but it requires frequent laboratory monitoring to maintain international normalized ratio levels in the therapeutic range. Dabigatran, a novel oral anticoagulant (OAC), has demonstrated efficacy in reducing the risk of stroke and systemic embolism and does not require laboratory monitoring. OBJECTIVE: To compare health care resource utilization (HCRU) and costs of OAC-naive patients newly diagnosed with nonvalvular atrial fibrillation (NVAF), using dabigatran or warfarin. METHODS: This retrospective observational study used data from medical and pharmacy claims extracted from the HealthCore Integrated Research Database representing commercial and Medicare Advantage members. Adults aged > 18 years with a medical diagnosis claim of NVAF were identified between October 1, 2010, and December 31, 2011. The date of first observed OAC prescription claim was the index date. Patients were followed for up to 12 months after the index date. Patients were assigned to the dabigatran or warfarin treatment groups based on their first OAC prescription fills. To reduce potential for selection bias, the cohorts were matched on baseline characteristics using propensity score matching. HCRU was measured and compared between groups on a per-patient-per-month (PPPM) basis for all-cause HCRU, as well as stroke, myocardial infarction, and bleed-specific HCRU. Pharmacy, medical, and total costs were also compared and adjusted to 2012 U.S. dollars. Generalized linear models were conducted to compare all-cause health care costs between cohorts. RESULTS: After propensity score matching, 1,648 patients were included in the analysis (824 each in the dabigatran and warfarin treatment groups). In the post-index period, patients in the dabigatran group had significantly fewer all-cause PPPM physician office visits (mean [SD] 1.29 [± 0.95] vs. 2.02 [± 1.53], P < 0.001) and outpatient visits (mean [SD] 2.17 [± 2.90] vs. 3.52 [± 3.32], P < 0.001) compared with those in the warfarin group. There were no between-group differences in outcomes for the number of stroke, myocardial infarction, or bleeding-related office visits. All-cause medical costs for the dabigatran cohort were lower than the warfarin cohort; however, the difference did not reach statistical significance ($2,696 [SD ± $6,699] vs. $2,893 [± $6,819], P = 0.179). All-cause pharmacy costs were higher in the dabigatran group versus the warfarin group ($455 [± $429] vs. $328 [± $517], P < 0.001). The dabigatran cohort also had significantly higher stroke-related ($32 [± $71] vs. $20 [± $55], P = 0.006) and nonstroke-related pharmacy costs ($423 [± $422] vs. $308 [± $515], P < 0.001). Despite higher pharmacy costs for the dabigatran cohort, both treatment groups had statistically similar all-cause total costs ($3,151 [± $6,744] vs. $3,221 [± $6,869], P = 0.701). CONCLUSIONS: This real-world study showed that among patients newly diagnosed with NVAF who were OAC naive, dabigatran use was associated with significantly less HCRU in terms of physician and outpatient visits but higher pharmaceutical costs in up to 12 months of follow-up. Similar to other real-world studies, this research supports the finding that higher pharmacy costs for dabigatran users was offset by lower medical costs, making total health care costs comparable between dabigatran and warfarin.