Real world effectiveness of warfarin among ischemic stroke patients with atrial fibrillation: observational analysis from Patient-Centered Research into Outcomes Stroke Patients Prefer and Effectiveness Research (PROSPER) study

Drs. Clements and Abdullah question the bridging anticoagulation in patients taking warfarin around the time of a surgical procedure. We agree this is a critical important question, but unfortunately cannot be answered in our current study. The PROSPER study focused on warfarin naive patients with atrial fibrillation and evaluated the effectiveness of warfarin therapy after these patients experienced an ischemic stroke. As such, none of the study individual met the bridging criteria. A randomized, double-blind, place-controlled trial (BRIDGE) has been recently published.1 Results from the BRIDGE trial could provide insight into the perioperative bridging anticoagulation in patients with atrial fibrillation who are on long-term warfarin treatment.
1. Douketis JD, Spyropoulos AC, Kaatz S, Becker RC, Caprini JA, Dunn AS, Garcia DA, Jacobson A, Jaffer AK, Kong DF, Schulman S, Turpie AGG, Hasselblad V and Ortel TL. Perioperative Bridging Anticoagulation in Patients with Atrial Fibrillation. New England Journal of Medicine. 2015;373:823-833.

Dr. Gupta question the conclusion due to potential treatment selection in patients with high-risk of bleeding (therefore were not prescribed warfarin at discharge) and a younger and relatively healthy cohort who prescribed warfarin at discharge. While we agree that bleeding tendency could influence treatment decision, our analysis excluded patients with documented contraindications including risk for bleeding, risk of falls, serious side effect to medication, etc. We agree that warfarin patients were slightly younger and healthy in terms of comorbidities as compared with those not receiving warfarin at discharge. However, none of these differences were statistically significant after propensity score inverse probability weighting adjustment (Data Supplement, Figure B).

We fully agree with Dr. Achanta the importance of novel oral anticoagulants in prevention of stroke and thromboembolic events. As part of the PROSPER project, additional study is underway to evaluate the clinical effectiveness of warfarin vs. novel oral anticoagulants in ischemic stroke patients with atrial fibrillation.