title: Evaluation of an electronic warfarin nomogram for anticoagulation of hemodialysis patients.
abstract: BACKGROUND
  Warfarin nomograms to guide dosing have been shown to improve control of the international normalized ratio (INR) in the general outpatient setting. However, the effectiveness of these nomograms in hemodialysis patients is unknown. We evaluated the effectiveness of anticoagulation using an electronic warfarin nomogram administered by nurses in outpatient hemodialysis patients, compared to physician directed therapy.
  
  
  METHODS
  Hemodialysis patients at any of the six outpatient clinics in Calgary, Alberta, treated with warfarin anticoagulation were included. Two five-month time periods were compared: prior to and post implementation of the nomogram. The primary endpoint was adequacy of anticoagulation (proportion of INR measurements within range ± 0.5 units).
  
  
  RESULTS
  Overall, 67 patients were included in the pre- and 55 in the post-period (with 40 patients in both periods). Using generalized linear mixed models, the adequacy of INR control was similar in both periods for all range INR levels: in detail, range INR 1.5 to 2.5 (pre 93.6% (95% CI: 88.6% - 96.5%); post 95.6% (95% CI: 89.4% - 98.3%); p = 0.95); INR 2.0 to 3.0 (pre 82.2% (95% CI: 77.9% - 85.8%); post 77.4% (95% CI: 72.0% - 82.0%); p = 0.20); and, INR 2.5 to 3.5 (pre 84.3% (95% CI: 59.4% - 95.1%); post 66.8% (95% CI: 39.9% - 86.0%); p = 0.29). The mean number of INR measurements per patient decreased significantly between the pre- (30.5, 95% CI: 27.0 - 34.0) and post- (22.3, 95% CI: 18.4 - 26.1) (p = 0.003) period. There were 3 bleeding events in each of the periods.
  
  
  CONCLUSIONS
  An electronic warfarin anticoagulation nomogram administered by nurses achieved INR control similar to that of physician directed therapy among hemodialysis patients in an outpatient setting, with a significant reduction in frequency of testing. Future controlled trials are required to confirm the efficacy of this nomogram.
authors.affiliation: Department of Medicine, University of Calgary, Calgary, Alberta Canada.
authors.forename: Benjamin K A
authors.initials: BK
authors.lastname: Thomson
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: MacRae
authors.forename: Lianne
authors.initials: L
authors.lastname: Barnieh
authors.forename: Jianguo
authors.initials: J
authors.lastname: Zhang
authors.forename: Elizabeth
authors.initials: E
authors.lastname: MacKay
authors.forename: Megan A
authors.initials: MA
authors.lastname: Manning
authors.forename: Brenda R
authors.initials: BR
authors.lastname: Hemmelgarn
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000379:methods; D000925:Anticoagulants / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D057286:Electronic Health Records; D005260:Female; D006801:Humans; D019934:International Normalized Ratio; D007676:Kidney Failure, Chronic / Q000451:nursing / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D013041:Specialties, Nursing / Q000379:methods; D013927:Thrombosis / Q000451:nursing / Q000517:prevention & control*; D014859:Warfarin / Q000008:administration & dosage*
chemical_list: D000925:Anticoagulants; D014859:Warfarin