Abstract 16227: Safety and Effectiveness of Dabigatran Relative to Warfarin in Routine Care
Introduction: It is important to quantify the comparative safety and effectiveness of new drugs in routine care.
Hypothesis: To assess the safety and effectiveness of dabigatran compared to warfarin in a sequential long-term study program in patients in routine care.
Methods: This program uses 2 large commercial US health insurance databases and propensity score matching to compare new users of dabigatran and warfarin with respect to ischemic and bleeding events, with planned interim analyses.
Results: From Oct 2010 through Dec 2012 patients with non-valvular atrial fibrillation and CHA2DS2-VASc scores ≥1 who initiated dabigatran, were matched (1:1) to warfarin initiators using a propensity score that balanced known risk factors for ischemic and bleeding events (Table). Follow-up until discontinuation of the anticoagulant, outcome event, or disenrollment was an average of 5 months (dabigatran) and 4 months (warfarin). Interim results indicate a 23% stroke rate reduction by dabigatran in a pooled analysis: HR=0.77, 95% CI=0.55-1.09. In the larger MarketScan database alone the stroke reduction was 36% (HR=0.64, 95% CI=0.44-0.95). There were only 26 strokes in the smaller Optum database leading to wide confidence intervals: HR=1.62, 95% CI=0.72-3.66. There was a 25% reduction in the rate of major hemorrhage: pooled HR=0.75, 95% CI=0.65-0.87 (MarketScan: HR=0.78 (95% CI=0.67-0.91), Optum: HR=0.56 (95% CI = 0.36-0.86)).
Conclusions: Interim results from this sequential long-term study program of patients in routine care suggest that dabigatran has improved effectiveness and safety relative to warfarin. Results highlight the limitations of small event numbers, e.g. stroke in anticoagulated patients, in early stages of post-marketing monitoring programs making chance a likely explanation for variations in point estimates between databases. Assessments of effectiveness beyond the first six months of therapy are limited by the short average follow-up.
Author Disclosures: J.D. Seeger: Employment; Significant; Optum, WHISCON. Research Grant; Significant; Research supported by research contract with BI. D.B. Bartels: Employment; Significant; Employee Boehringer Ingelheim. K. Huybrechts: Research Grant; Significant; Research supported by research contract with BI. K. Bykov: Research Grant; Significant; research supported by research contract with BI. D. Shash: Employment; Significant; Employee Boehringer Ingelheim. K. Zint: Employment; Significant; Employee Boehringer Ingelheim. S. Schneeweiss: Research Grant; Significant; Research supported by research contract with BI.
- © 2014 by American Heart Association, Inc.