Using warfarin increases the risk o...

Using warfarin increases the risk of hemorrhage, particularly when the International Normalized Ratio (INR) rises above the therapeutic range. greatest in number experts agree that when the INR outstrips four or five, the warfarin dosage should be decreased. However, there generally is no consensus about to what degree to treat the asymptomatic patient who has a mildly elevated INR in the 32 to 34 range. about experts would continue the generally received dosage for a period of time, while others would restore the total weekly dosage by dint of 2 to 18 percent. Banet and associates evaluated the safety of not changing the warfarin dosage because of a mildly elevated INR and quantified the relationship between reduction of the warfarin dosage and succeeding decrease of the INR.

The inquiry was a randomized controlled trial of outpatients who were receiving warfarin therapy at eight health maintenance center Investigators identified patients who had a mildly elevated INR between 32 and 34 To be included in the research the patients had to be asymptomatic, have been using warfarin for at least 30 days, and have a previous therapeutic INR (20 to 30) Four of the center were randomized to have access to a telephone-based anticoagulation service, and at the other four center patients continued to be managed by dint of their primary care physicians. The difference between the couple groups was that the anticoagulation service had an established protocol that patients with mildly elevated INRs were to be maintained onward the same dosage unless it was clinically indicated to attenuate the dosage, while the primary care cluster had no established protocol. In addition, the anticoagulation service telephon each patient who had an elevated INR and asked about any potential cause for the increase and assessed any risk for bleeding. The warfarin dosage, and the time and value of the follow-up INR were recorded for analysis. Adverse conclusions were recorded for the anticoagulation group

A cohort of 231 patients (41 percent were women; mean age: 72 years) was analyzed for the cogitation with 103 of those in the anticoagulation service assemblage The anticoagulation service group had solely one episode of epistaxis in the 30 days after the elevated INR. Patients in the primary care cluster were more likely to have a reduction in their warfarin dosage than patients in the anticoagulation service form into groups There was no difference between the sum of two units groups with regard to the median INR. In a subgroup analysis, the patients in the anticoagulation service cluster were more likely to have a follow-up therapeutic INR than those in the primary care arrange The median follow-up INR in those with no change in the dosage was 27 25 in those who reduc the dosage by dint of 1 to 20 percent, and 17 in patients who had the dosage reduc by means of 21 to 43 percent.

The authors decide that maintaining the same warfarin dosage in asymptomatic patients with a slightly elevated INR of 32 to 34 is appropriate management for these patients. They add that a dosage reduction of more than 20 percent should be avoided in patients with mild elevation of the INR because of the increased risk of following adverse events.

Banet GA, et al. Warfarin dose reduction v watchful waiting for mild elevations in the international normalized ratio. Chest February 2003;123:499-503

EDITOR'S NOTE: single of the more challenging medications to manage is warfarin. The use of warfarin has increased in novel years because of the expanded indication for the prevention of thump in patients with atrial fibrillation, established treatments for penetrating venous thrombosis or pulmonary emboli, and thrombosis prevention in patients with mechanical heart valves. The difficulty with warfarin is the number of drug-drug interactions and the impact that diet changes can have in succession the INR. Banet and associates have shown that, in patients with alone a mildly elevated INR, a reasonable alternative to changing medications is waiting and watching. In addition, reducing the warfarin dosage by the agency of more than 20 percent serves to drop the INR below the target of 20 This strategy provides physicians with a management option that does not increase the risk of bleeding moreover also does not decrease the INR to subtherapeutic levels--KEM

COPYRIGHT 2003 American Academy of Family Physicians

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