title: Postdischarge international normalized ratio testing and long-term clinical outcomes of patients with heart failure receiving warfarin: findings from the ADHERE registry linked to Medicare claims.
abstract: BACKGROUND
  Effective warfarin thromboprophylaxis requires maintaining anticoagulation within the recommended international normalized ratio (INR) range. INR testing rates and associations between testing and outcomes are not well understood.
  
  
  OBJECTIVE
  INR testing rates after hospitalization for acute decompensated heart failure are suboptimal, and testing is associated with lower risks of mortality and adverse clinical events.
  
  
  METHODS
  We conducted a retrospective cohort study of patients who were long-term warfarin users and were hospitalized for heart failure, had a medical history of atrial fibrillation or valvular heart disease, and were enrolled in fee-for-service Medicare. INR testing was defined as ≥1 outpatient INR test within 45 days after discharge. Using Cox proportional hazards models, we examined associations between testing and all-cause mortality, all-cause readmission, and adverse clinical events at 1 year.
  
  
  RESULTS
  Among 8558 patients, 7722 (90.2%) were tested. After 1 year, tested patients had lower all-cause mortality (23.5% vs 32.6%; P < 0.001) and fewer myocardial infarctions (2.0% vs 3.3%; P = 0.02). These differences remained significant after multivariable adjustment with hazard ratios of 0.72 (95% confidence interval [CI]: 0.63-0.84; P < 0.001) and 0.58 (95% CI: 0.41-0.83; P = 0.003), respectively. Differences in all-cause readmission, thromboembolic events, ischemic stroke, and bleeding events were not statistically significant.
  
  
  CONCLUSIONS
  Postdischarge outpatient INR testing in patients with heart failure complicated by atrial fibrillation or valvular heart disease was high. INR testing was associated with improved survival and fewer myocardial infarctions at 1 year but was not independently associated with other adverse clinical events.
authors.affiliation: Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina.
authors.forename: Laura G
authors.initials: LG
authors.lastname: Qualls
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Greiner
authors.forename: Zubin J
authors.initials: ZJ
authors.lastname: Eapen
authors.forename: Gregg C
authors.initials: GC
authors.lastname: Fonarow
authors.forename: Roger M
authors.initials: RM
authors.lastname: Mills
authors.forename: Winslow
authors.initials: W
authors.lastname: Klaskala
authors.forename: Adrian F
authors.initials: AF
authors.lastname: Hernandez
authors.forename: Lesley H
authors.initials: LH
authors.lastname: Curtis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality; D001777:Blood Coagulation / Q000187:drug effects*; D016009:Chi-Square Distribution; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D006349:Heart Valve Diseases / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality; D006801:Humans; D007356:Insurance, Pharmaceutical Services; D019934:International Normalized Ratio; D053208:Kaplan-Meier Estimate; D008297:Male; D006278:Medicare; D015999:Multivariate Analysis; D010351:Patient Discharge; D010359:Patient Readmission; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin