Abstract 14400: The Association Between Bleeding and Warfarin Discontinuation in Patients with Atrial Fibrillation

Abstract

Purpose: Bleeding is an adverse event of warfarin use and may lead to warfarin discontinuation. This study aimed to quantify the association between bleeding during or resulting in a hospitalization and warfarin discontinuation in AF patients.

Methods: We conducted a nested case-control study within a population-based cohort using an administrative claims database (i3 InVision Data Mart [Ingenix, Eden Prairie, MN]). The cohort included all patients at least 18 years of age with a diagnosis of AF between 2005 and 2010. Patients were treated (minimum of 60 days) with warfarin and had at least one CHADS₂ risk factor for stroke (75 or older, prior stroke, CHF, diabetes, hypertension). Patients with mitral stenosis or transient AF were excluded. Patients were followed from the initiation of warfarin treatment. During the follow-up, all discontinuations (at least 180 days without warfarin treatment) were identified as cases. Controls were selected from the patients who continued on warfarin at the time when cases discontinued warfarin, and were matched to each case on age (± 3), gender, year of initiating warfarin treatment (± 3), and CHADS₂. Bleeding events during or resulting in a hospitalization were examined in the 60-day period immediately prior to warfarin discontinuation. Conditional logistic regression models were used to estimate rate ratios, adjusted for potential confounders.

Results: A total of 18,222 patients (6455 cases and 11,767 controls) were included in the analysis; 64% were male and the mean age was 68 years. Mean warfarin treatment duration was 5.5 months and mean CHADS₂ score was 2.2. The proportion of AF patients diagnosed with bleeding (during a hospital stay) within 60 days prior to the discontinuation was 4.7% (297) among those who subsequently discontinued warfarin, and 0.8% (92) among the matched controls. The rate ratio was 6.2 (95% CI, 4.8-8.0), after adjusting for cardioversion. (Adjusting for high frequency surgical procedures did not change the results.)

Conclusions: Hospitalized bleeding was associated with a 6-fold increased likelihood of warfarin discontinuation, as compared with no hospitalized bleeding. Further research on the prognosis of bleeding and warfarin discontinuation is warranted.