Evaluation of point‐of‐care International Normalized Ratio in sickle cell disease. Issue 4 (27th May 2021)

• Record Type: Journal Article
• Authors: Rahman, Syeda; Srisuwananukorn, Andrew; Molokie, Robert E.; Gowhari, Michel; Njoku, Franklin; Hussain, Faiz Ahmed; Lee, James; Nutescu, Edith A.; Gordeuk, Victor R.; Saraf, Santosh L.; Han, Jin
• Is Part Of: Research and practice in thrombosis and haemostasis. Volume 5:Issue 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-05-27
• Subjects: Thrombosis -- Periodicals; Hemostasis -- Periodicals; 616.135005
• DOI: 10.1002/rth2.12533
• Languages: English
• ISSNs: 2475-0379

Abstract

Abstract: Background: Point‐of‐care (POC) International Normalized Ratio (INR) measurement provides efficient monitoring of warfarin therapy; however, its reliability may be affected in patients with anemia, such as those with sickle cell disease (SCD). Objectives: To evaluate the correlation of POC‐INR to clinical laboratory INR (CL‐INR) in SCD and use of a correction factor. Patient/Methods: In this retrospective study, the accuracy of POC‐INR compared to CL‐INR was evaluated in a cohort of patients with SCD and in a non‐SCD Black cohort. Results: Despite the difference in anemia, the SCD cohort showed a similar percentage of in‐range POC‐INR values as observed in the non‐SCD cohort (37% vs 42%). The SCD cohort was randomly divided to form discovery and validation cohorts. In the discovery cohort, 86% of POC‐INRs were in range when the POC‐INRs were ˂4.0, but only 24% were in range if POC‐INRs were ≥4.0. A linear regression of CL‐INR versus POC‐INR for POC‐INR values ≥4.0 yielded a coefficient of 0.72 (95% confidence interval, 0.69‐0.75); Multiplying POC‐INR by this correction factor, rounded to 0.7 for ease of use in clinical practice, improved the proportion of in‐range POC‐INR values ≥4.0 from 24% to 100% in the SCD discovery cohort and from 19% to 95% in the SCD validation cohort. Similar findings applied to analyses of the non‐SCD cohort. Conclusions: POC‐INR and CL‐INR in patients with SCD are similar when POC‐INR is <4.0, and the accuracy of POC‐INR values ≥4.0 can be improved by applying an institution‐specific correction factor.