title: Critical international normalized ratio results after hours: To call or not to call?
abstract: OBJECTIVE
  To determine whether the timing of notification of critical international normalized ratio (INR) results (during or after clinic hours) altered the clinician's ability to affect same-day patient care.
  
  
  METHODS
  Retrospective chart review.
  
  
  METHODS
  The Anticoagulation Management Service at the University of Alberta Hospital in Edmonton.
  
  
  METHODS
  A total of 276 patients with critical INR results (> 5.0) separated by at least 30 days were identified to have 200 critical INR results reported during clinic hours and 200 reported after hours.
  
  
  METHODS
  Differences in the proportion of patients with critical INR results having same-day care altered (by changing warfarin dose, administering vitamin K, or referring for assessment) between those with results reported during clinic hours compared with those with results reported after clinic hours. Differences by highly critical INR results (> 9.0 vs ≤ 9.0) and whether patients experienced thromboembolism or bleeding within 30 days were also assessed.
  
  
  RESULTS
  Same-day patient care was affected for 174 out of 200 (87.0%) critical INR results reported during clinic hours compared with 101 out of 200 (50.5%) reported after clinic hours (P< .001). The most common reason for not being able to intervene was that warfarin had already been taken. Warfarin dose alteration was the most frequent change (97.1% during clinic hours and 96.0% after hours). When patients with INRs greater than 9.0 were assessed separately, the ability to affect care increased for INRs reported both during and after clinic hours (92.9% and 63.6%, respectively), largely attributable to oral vitamin K use. Overall, thromboembolic and major bleeding event rates were low and were similar in both groups.
  
  
  CONCLUSIONS
  Same-day care was less likely to be affected by critical INR results communicated after hours, most commonly because the patient had already taken their daily warfarin dose. However, after-hours care was still affected for 1 out of 2 patients, which is meaningful and supports current practice.
authors.affiliation: Clinical pharmacist at the Misericordia Hospital in Edmonton, Alta.
authors.forename: Darlene
authors.initials: D
authors.lastname: Korn
authors.affiliation: Associate Professor of Medicine in the Department of Medicine at the University of Alberta, Medical Director of the University of Alberta Hospital Anticoagulation Management Service, and a practising cardiologist at the Mazankowski Alberta Heart Institute in Edmonton.
authors.forename: M
authors.initials: M
authors.lastname: Sean McMurtry
authors.affiliation: Clinical practice leader within Pharmacy Services for Alberta Health Services in Edmonton.
authors.forename: Kirsten
authors.initials: K
authors.lastname: George-Phillips
authors.affiliation: Director of the University of Alberta Hospital Anticoagulation Management Service and Associate Professor of Medicine in the Division of Cardiology at the University of Alberta. tammy.bungard@ualberta.ca.
authors.forename: Tammy J
authors.initials: TJ
authors.lastname: Bungard
mesh_terms: D039602:After-Hours Care; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage; D000933:Antifibrinolytic Agents / Q000008:administration & dosage; D001778:Blood Coagulation Disorders / Q000097:blood* / Q000628:therapy*; D005260:Female; D006470:Hemorrhage / Q000517:prevention & control; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D012017:Referral and Consultation; D012189:Retrospective Studies; D013923:Thromboembolism / Q000517:prevention & control; D013997:Time Factors; D014812:Vitamin K / Q000008:administration & dosage; D014859:Warfarin / Q000008:administration & dosage
chemical_list: D000925:Anticoagulants; D000933:Antifibrinolytic Agents; D014812:Vitamin K; D014859:Warfarin