Supplementary Material for:Association between Renal Function and Bleeding Risk for Dabigatran after Switching from Warfarin

Background: There is a higher risk of gastrointestinal (GI) bleeding in patients treated with dabigatran versus warfarin. We analyzed the impact of renal function on the relative risk of bleeding in patients converted to dabigatran. Methods: Patients aged ≥65 years who received anticoagulation with warfarin for a minimum of 6 months and subsequently converted to dabigatran or remained on warfarin were studied. Data sources included VA National Patient Care, and VA Decision Support System National Pharmacy and Laboratory. Each patient who converted to dabigatran 150 mg twice daily was matched by propensity score with 2 patients on warfarin who did not convert. Outcomes included rates of hospital admission for GI or other major bleeding and mortality, stratified by estimated glomerular filtration rate (eGFR).Results: Study population included 864 patients who converted and 1,710 patients who did not convert to dabigatran. In patients with eGFR 50-80 ml/min/1.73 m², the hazard of GI bleeding in patients who initiated dabigatran was nearly 3 times higher, (4.1 vs. 1.3 per 100 patient years; hazards ratio 2.94; 95% CI 1.24-7.02; p = 0.015), compared to patients who remained on warfarin. There were relatively few patients with eGFR <50 or >80 ml/min/1.73 m2, and relatively few bleeding events outside the GI tract. Conclusions: Prescribing healthcare providers should exercise caution and close monitoring for bleeding complications when converting from warfarin to dabigatran, even in patients with renal function in the range considered safe for dabigatran use as per current recommendations.