Cost Savings Associated with Extended INR Testing Intervals

Document Type

Conference Proceeding

Publication Date


Publication Title

Res Pract Thromb Haemost


Background : Guidelines recommend extended INR testing intervals (>4 weeks) in stable patients on vitamin K antagonists. The economic impact of extended intervals has not been fully elucidated. Aims : To estimate potential cost savings in six anticoagulation clinics after initiation of an extended INR testing interval protocol. Methods : MAQI 2 is a quality collaborative of 6 anticoagulation clinics in the United States that abstract data on a random sample of patients initiating warfarin for any indication. We began offering extended INR testing intervals (>4 weeks) to eligible patients with stable INRs and warfarin dosing in 2014. Using the t- test, we compared the mean number of INRs per year for eligible patients that received at least one planned INR interval of 5 or more weeks (extended cohort) with those that did not (non- extended cohort) from January 1, 2014 to December 31, 2018. Cost savings were estimated by multiplying the composite labor and laboratory costs of an INR ($7.18 USD) by the number of eligible patients who received extended INR testing intervals and the mean reduction in yearly INR tests. Results : 1036 of 3506 (26.5%) of warfarin patients met eligibility criteria. 930/1036 (89.7%) had at least one extended testing interval. Mean (sd) number of INRs per year were 17.4 (6.6) and 24.9 (9.0), [absolute difference 7.5] in the extended and non- extended cohorts of patients who were eligible for extended INR testing intervals (p< 0.01). Estimated cost savings in the extended cohort was $50,080 USD per year. Extrapolation to the ∼15,000 patients in our 6 anticoagulation clinics yields a potential cost savings of $214,200 USD per year. Conclusions : Approximately one quarter of patients in a sample of our anticoagulation clinics were candidates for extended INR interval testing. Most eligible patients received extended INR testing intervals, resulting in fewer INR lab tests and sizeable labor and laboratory cost savings.



First Page


This document is currently not available here.