title: Changes in Warfarin Sensitivity During Decompensated Heart Failure and Chronic Obstructive Pulmonary Disease.
abstract: BACKGROUND
  Heart failure (HF) has been associated with an elevated international normalized ratio (INR) in patients on warfarin.
  
  
  OBJECTIVE
  Compare warfarin sensitivity during hospital admission for HF exacerbation and chronic obstructive pulmonary disease (COPD) exacerbation with admissions unrelated to HF or COPD (controls) as well as during disease stability.
  
  
  METHODS
  We conducted a case-controlled observational study. Patients admitted to a tertiary teaching hospital for HF exacerbation (n = 37), COPD exacerbation (n = 26), and admissions unrelated to HF or COPD (controls, n = 60) were included. Warfarin sensitivity (INR per daily mg dose of warfarin) at admission was compared to periods of disease stability and also compared between the 3 groups.
  
  
  RESULTS
  The increase in warfarin sensitivity at admission was 94% for HF patients (P < 0.0001), 59% for COPD (P = 0.003) patients, and 24% for controls (P = 0.002). HF patients with New York Heart Association (NYHA) class 3 and 4 and NYHA class 1 and 2 experienced changes in warfarin sensitivity of 125% (P = 0.006) and 50% (P = 0.13) at admission. HF patients had higher warfarin sensitivity at admission (mean = 1.62 [SD = 1.27]) compared to the control group (0.91 [0.52], P < 0.0001) and COPD group (1.03 [0.79], P = 0.04). and required greater intervention with vitamin K than controls (14% vs 0%, P = 0.007).
  
  
  CONCLUSIONS
  HF and COPD patients were more sensitive to warfarin during disease exacerbation, with HF exacerbation having the largest impact, resulting in clinically significant management implications.
authors.affiliation: Pharmacy, Flinders Medical Centre, Flinders Drive, Bedford Park, 5042 SA, Australia.
authors.forename: Michaela
authors.initials: M
authors.lastname: del Campo
authors.affiliation: Pharmacy, Flinders Medical Centre, Flinders Drive, Bedford Park, 5042 SA, Australia greg.roberts2@health.sa.gov.au.
authors.forename: Greg
authors.initials: G
authors.lastname: Roberts
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D006333:Heart Failure / Q000188:drug therapy*; D006760:Hospitalization; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy*; D014812:Vitamin K / Q000627:therapeutic use; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014812:Vitamin K; D014859:Warfarin
keywords: anticoagulation; chronic obstructive pulmonary disease; congestive heart failure; medication safety; warfarin