Pharmacy-managed protocol for warfarin use in orthopedic surgery patients

M. P. Rivey, R. D. Wood, D. R. Allington, T. P. Stratton, C. C. Erickson, T. A. Stenson

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


A pharmacy-managed protocol for warfarin use in orthopedic surgery patients was studied. In 1990 a protocol designed to accommodate either protocol or physician-determined dosing of warfarin for orthopedic antithrombotic prophylaxis (OAP) was implemented at a community hospital. A 'protocol' group consisting of patients treated entirely under the protocol- determined dosing option was prospectively identified over a two-year period. A 'physician' group consisting of patients treated by physicians in the 10 months immediately preceding implementation of the protocol was also identified. The ability of the protocol to achieve laboratory-test and clinical goals was assessed by comparing the two groups. The proportion of patients who received OAP increased from 89% for the physician group to 98% for the protocol group. Mean prothrombin times (PTs) were significantly higher in the protocol group only on postoperative day 2; 66% of all PTs beyond postoperative day 1 in the protocol group were within the targeted range, which reflected an International Normalized Ratio of 1.6-3.2. The frequencies of clinically apparent postoperative thromboric events and bleeding episodes were low in each group and comparable to literature values. Analysis of protocol-group patients with PTs of >20 seconds indicated that lower weight, female sex, and blood loss during surgery were associated with an elevated PT. The protocol was revised to provide for a lower initial warfarin dose in elderly women. A pharmacy-managed protocol for dosing warfarin achieved therapeutic goals and promoted nearly universal use of OAP in patients undergoing high-risk orthopedic surgery.

Original languageEnglish (US)
Pages (from-to)1310-1316
Number of pages7
JournalAmerican Journal of Health-System Pharmacy
Issue number12
StatePublished - Jan 1 1995


  • Anticoagulants
  • Dosage
  • Geriatrics
  • Pharmaceutical services
  • Pharmacy, institutional, hospital
  • Physicians
  • Prescribing
  • Protocols
  • Toxicity
  • Warfarin
  • Women


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