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Is it Safe to Send Stable Anticoagulation Clinic Patients Back to Usual Medical Care? No!

Henry I. Bussey, Pharm.D.
April, 2008

Garwood and colleagues reported a substantial deterioration in INR control and a worsening of event rates when 40 stable anticoagulation clinic (AC) patients were referred back to usual medical care (UMC).1 The difference in INR control during the AC vs UMC periods was comparable to that which, in a recent larger study, was found to be associated with a doubling in the rate of stroke, myocardial infarction, major hemorrhage, and death in patients with atrial fibrillation.2

Specifically, after return to UMC, the frequency of monitoring became less frequent and more variable (8.9 +/- 2 INRs/patient/ 6 months vs. 5.2 +/- 4.9 INRs/patient/ 6 months); INR control fell from 76 %in range to 48% in range - or a median % INR in range per patient from 75% to 36.5%. During the 6 month AC period one patient experienced 2 clinical events that required medical attention vs. 7 patients who had 13 clinical events during the subsequent UMC period. During the AC period only 1% of INRs were < 1.5 and 1% were > 4.5. During the UMC period, the corresponding rates were 12% and 5%. Such an increase in INRs at the extremes is very troubling since the rate of new clots and major bleeding tends to increase exponentially when the INR falls below 1.5 or rises above 4.5, respectively.

Other studies have reported improved anticoagulation management when patients on warfarin were moved from UMC to AC care but the report by Garwood and colleagues is the first evaluation I am aware of that has examined the impact of referring stable AC patients back to UMC. I am aware of numerous instances in which referral of stable AC patients back to UMC has been considered as an option to reduce the workload on an over-burdened AC. In fact, implementing such a practice was the incentive for Garwood's study. Comparing results across studies would suggest that the hazards of UMC are similar for those patients initially managed by UMC as well as for those whose therapy is stabilized in an AC before being referred back to UMC. These data show that safe and effective anticoagulation therapy requires that patients continue to be managed by an AC. Therefore, health care settings must find ways to adequately support growing AC services.


  1. Garwood CL, Dumo P, Baringhaus SN, Laban KM. Quality of anticoagulation care in patients discharged from a pharmacist-managed anticoagulation clinic after stabilization of warfarin therapy. Pharmacotherapy. 2008 Jan;28(1):20-6.

  2. White HD, Gruber M, Feyzi J, et al. Comparison of outcomes among patients randomized to warfarin therapy according to anticoagulant control: results from SPORTIF III and V. Arch Intern Med. 2007 Feb 12;167(3):239-45.
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Saturday, July 13, 2024