• Hemostasis / Coagulation

  Extended International Normalized Ratio testing intervals for warfarin-treated p

  Posted by Web master on March 9, 2025 at 10:41 PM

  J Thromb Haemost. 2018 Jul;16(7):1307-1312. doi: 10.1111/jth.14150. Epub 2018 Jun 6.

  Barnes GD1, Kong X1, Cole D2, Haymart B1, Kline-Rogers E1, Almany S3, Dahu M4, Ekola M5, Kaatz S6, Kozlowski J7, Froehlich JB1.
  Author information

  Abstract
  Essentials Warfarin typically requires International Normalized Ratio (INR) testing at least every 4 weeks. We implemented extended INR testing for stable warfarin patients in six anticoagulation clinics. Use of extended INR testing increased from 41.8% to 69.3% over the 3 year study. Use of extended INR testing appeared safe and effective.

  https://www.ncbi.nlm.nih.gov/pubmed/29763979

  SUMMARY:
  Background A previous single-center randomized trial suggested that patients with stable International Normalized Ratio (INR) values could safely receive INR testing as infrequently as every 12 weeks. Objective To test the success of implementation of an extended INR testing interval for stable warfarin patients in a practice-based, multicenter collaborative of anticoagulation clinics. Methods At six anticoagulation clinics, patients were identified as being eligible for extended INR testing on the basis of prior INR value stability and minimal warfarin dose changes between 2014 and 2016. We assessed the frequency with which anticoagulation clinic providers recommended an extended INR testing interval (> 5 weeks) to eligible patients. We also explored safety outcomes for eligible patients, including next INR values, bleeding events, and emergency department visits. Results At least one eligible period for extended INR testing was identified in 890 of 3362 (26.5%) warfarin-treated patients. Overall, the use of extended INR testing in eligible patients increased from 41.8% in the first quarter of 2014 to 69.3% in the fourth quarter of 2016. The number of subsequent out-of-range next INR values were similar between eligible patients who did and did not have an extended INR testing interval (27.3% versus 28.4%, respectively). The numbers of major bleeding events were not different between the two groups, but rates of clinically relevant non-major bleeding (0.02 per 100 patient-years versus 0.09 per 100 patient-years) and emergency department visits (0.07 per 100 patient-years versus 0.19 per 100 patient-years) were lower for eligible patients with extended INR testing intervals than for those with non-extended INR testing intervals. Conclusions Extended INR testing for stable warfarin patients can be successfully and safely implemented in diverse, practice-based anticoagulation clinic settings.

  © 2018 International Society on Thrombosis and Haemostasis.

  KEYWORDS:
  anticoagulation; atrial fibrillation; quality improvement; venous thromboembolism; warfarin

  On the Path to Fewer INR checks
  Anticoagulation clinics demonstrate feasibility, safety of extended testing intervals in stable patients taking warfarin.

  A study in the Journal of Thrombosis and Haemostasis was able to demonstrate that patients who were successfully managing their warfarin therapy could safely go beyond a month’s time between International Normalized Ratio (INR) blood draws. INR draws typically take place every 4 weeks to monitor patients on blood thinners. “We wanted to see if we could reduce the burden of frequent INR blood tests for patients who are very stable in managing their warfarin,” Geoffrey Barnes, MD, first author of the research and a cardiologist at the University of Michigan’s Frankel Cardiovascular Center, told CLN Stat.Fewer blood draws also means that nurses in the anticoagulation clinic would have fewer INR lab results that they had to process and manage, Barnes said.

  The American College of Chest Physicians in 2011 had issued a recommendation favoring INR testing every 12 weeks in stable warfarin patients, following the results of a single center trial that indicated the approach was safe and feasible. Despite these promising results, the approach had yet to be adopted in the clinic setting.

  Barnes’ study, the Michigan Anticoagulation Quality Improvement Initiative tested this approach on a broader scale, enlisting six anticoagulation centers in 2014 to extend their standard 4-week protocol for stable warfarin patients. All six did so, establishing a maximum of either 6 or 8 weeks. Among more than 3,360 warfarin-treated patients managed by these centers, 890 patients qualified for extended INR testing, 86.5% of which had their testing interval extended at least once. Through this method, the percentage of patients waiting longer than 5 weeks between blood draws increased from 41.8% in 2014 to 69.3% in 2016.

  “Eligible patients who had at least one extended INR testing interval had no significant differences in warfarin anticoagulation indications, gender or bleeding risk from patients who never had an extended INR testing interval despite being eligible,” the researchers indicated.

  The study demonstrated that anticoagulation clinics can successfully identify stable warfarin patients and recommend less frequent INR testing. It also showed that the approach was safe, without any increased risk of bleeding or emergency department visits. “Although this data had previously been tested in a randomized trial, our study demonstrates that this strategy can be implemented in a wide variety of anticoagulation clinics,” Barnes said. In following up with these patients, his team found that many of their centers were getting more comfortable with longer time periods between INR blood draws.

  “We will continue to study these patients to assess the safety and efficacy of this approach,” he said.

  

  ncbi.nlm.nih.gov

  Extended International Normalized Ratio testing intervals for warfarin-treated patients - PubMed

  Background A previous single-center randomized trial suggested that patients with stable International Normalized Ratio (INR) values could safely receive INR testing as infrequently as every 12 weeks. Objective To test the success of implementation of an extended INR testing interval … Continue reading

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