title: Out-of-range international normalized ratio values and healthcare cost among new warfarin patients with non-valvular atrial fibrillation.
abstract: BACKGROUND
  Patients with out-of-range international normalized ratio (INR) values <2.0 and >3.0 have been associated with increased risk of thromboembolic and bleeding events. INR monitoring is costly, because of associated physician and nurse time, laboratory resource use, and dose adjustments.
  
  
  OBJECTIVE
  This study assessed the healthcare cost burden associated with out-of-range INR among warfarin initiator patients diagnosed with non-valvular atrial fibrillation (NVAF) in the US Veterans Health Administration (VHA) population.
  
  
  METHODS
  Adult NVAF patients (≥18 years) initiating warfarin were selected from the VHA dataset for the study period October 1, 2007-September 30, 2012. Only valid INR measurements (0.5 ≤ INR ≤ 20) were examined for the follow-up period, from the index date (warfarin initiation date) until the end of warfarin exposure or death. All-cause healthcare costs within 30 days were measured starting from the second month (31 days post-index date) to the end of the study period. Costs for inpatient stays, emergency room, outpatient facility, physician office visits, and other services were computed separately. Multiple regression was performed using the generalized linear model for overall cost analysis.
  
  
  RESULTS
  In total, 29,463 patients were included in the study sample. Mean costs for out-of-range INR ranged from $3419 to $5126. Inpatient, outpatient, outpatient pharmacy, and total costs were significantly higher after patients experienced out-of-range results (INR < 2, INR > 3), compared with in-range INR (2 ≤ INR ≤ 3). When exposed to out-of-range INR, patients also incurred higher mean total costs within 2-6 months ($3840-$5820) than after the first 6 months ($2789-$3503) of warfarin therapy.
  
  
  CONCLUSIONS
  In the VHA population, INR measures outside of the 2-3 range were associated with significantly higher healthcare costs. Increased costs were especially apparent when INR values were below 2, although INR measures above 3 were also associated with higher costs relative to in-range values.
authors.affiliation: Janssen Scientific Affairs LLC , Raritan, NJ , USA.
authors.forename: Winnie W
authors.initials: WW
authors.lastname: Nelson
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Onur
authors.initials: O
authors.lastname: Baser
authors.forename: C V
authors.initials: CV
authors.lastname: Damaraju
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Schein
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000191:economics* / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy*; D003365:Costs and Cost Analysis; D005260:Female; D006296:Health Services / Q000191:economics / Q000706:statistics & numerical data; D006470:Hemorrhage / Q000191:economics; D006760:Hospitalization / Q000191:economics; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D017059:Models, Econometric; D013923:Thromboembolism / Q000191:economics; D014481:United States; D014493:United States Department of Veterans Affairs; D014859:Warfarin / Q000191:economics* / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D000925:Anticoagulants; D014859:Warfarin
keywords: Atrial fibrillation; Healthcare cost; International normalized ratio; Warfarin