Cardiovascular Disease |

Warfarin Management and Outcomes in Patients With Nonvalvular Atrial Fibrillation Within an Integrated Healthcare System FREE TO VIEW

JaeJin An, PhD; Fang Niu; Chengyi Zheng; Nazia Rashid; Robert Mendes; Diana Dills; Lien Vo; Prianka Singh; Amanda Bruno; Daniel Lang; Paul Le; Kristin Jazdzewski; Gustavus Aranda
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Western University of Health Sciences, Pomona, CA

Chest. 2015;148(4_MeetingAbstracts):64A. doi:10.1378/chest.2259208
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SESSION TITLE: Cardiovascular Disease Posters II

SESSION TYPE: Original Investigation Poster

PRESENTED ON: Wednesday, October 28, 2015 at 01:30 PM - 02:30 PM

PURPOSE: To investigate warfarin management and clinical outcomes associated with time-in-therapeutic range (TTR) in patients with non-valvular atrial fibrillation (NVAF).

METHODS: A retrospective cohort study was conducted among NVAF patients. Adult patients diagnosed with NVAF and ≥1 warfarin prescription were identified between 01/01/2006-12/31/2011 within Kaiser Permanente Southern California, and followed until 12/31/2013. Clinical outcomes included stroke/systemic embolism (SE), and major bleed. Descriptive statistics and multivariable Cox proportional hazard models were used to determine association between TTR and outcomes.

RESULTS: A total of 34,382 NVAF patients on warfarin treatment were identified and followed for a median of 3.8 years. About half (49%) of patients were newly initiating warfarin therapy. International normalized ratio (INR) monitoring and pharmacist interventions were conducted roughly every 3 weeks [mean (SD) days for INR monitoring was 20.8 (38.2) days, and 21.5 (15.8) days for intervention]. 63% of the study population had ≥1 warfarin dose adjustment during the first 6 months with a median of 5 annual dose adjustments. Warfarin dose adjustment occurred on a median of 1 day after the INR measurement. Median TTR was 61% with 27% of interquartile range. Stroke/SE rates (per 100 person-years) were 1.30 and major bleed rates were 9.01. TTR below median (< 61%) was associated with a higher risk of stroke/SE [hazard ratio (HR) (95% CI) = 1.96 (1.75-2.21)] as well as a higher risk of bleed [HR = 1.56 (1.49-1.64)] compared to TTR above median (≥ 61%). A linear association was found between the stroke/SE rates and TTR quartiles; 0.89, 0.94, 1.27, 2.76 (TTR ≥73%, 61-72%, 46-60%, <46%, respectively), but not between the major bleed rates and TTR; 7.81, 6.76, 8.52, 15.91 (TTR ≥73%, 61-72%, 46-60%, <46%, respectively). The high rates of stroke/SE and major bleed were driven by the lowest TTR quartiles.

CONCLUSIONS: Close monitoring with timely warfarin dose adjustments were found in patients with NVAF managed by pharmacist-led anticoagulation clinics. However, there were still substantial number of patients whose TTR was suboptimal and eventually experienced more stroke/SE and bleeding events.

CLINICAL IMPLICATIONS: Maintaining an appropriate level of TTR is important to maximize stroke/SE prevention benefits from warfarin therapy while minimizing bleed events. New treatment strategies for patients who are not able to reach optimal therapeutic ranges are necessary to improve outcomes.

DISCLOSURE: JaeJin An: Grant monies (from industry related sources): Bristol Myers Squibb/Pfizer, Grant monies (from industry related sources): Genentech Robert Mendes: Employee: Pfizer Diana Dills: Employee: Pfizer Lien Vo: Employee: BMS Prianka Singh: Employee: BMS Amanda Bruno: Employee: BMS Gustavus Aranda: Employee: BMS The following authors have nothing to disclose: Fang Niu, Chengyi Zheng, Nazia Rashid, Daniel Lang, Paul Le, Kristin Jazdzewski

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