Comparison of international normalized ratio determined by point-of-care to standard laboratory testing before and after reversal of heparin in cardiac surgery

Michael Fabbro, Miguel Abalo, Lilibeth Fermin, David M. Andrews, Prakash A. Patel

Research output: Contribution to journalArticlepeer-review

Abstract

Study ObjectiveTo compare point-of-care (POC) of international normalized ratio to laboratory-derived values before and after cardiopulmonary bypass, with the primary aim of evaluating for any change in the relationship between the tests.MethodsThis is a prospective observational study with 50 patients undergoing cardiac surgery enrolled. The International normalized ratio measured at two time points, precardiopulmonary bypass and after heparin reversal with protamine using both POC i-STAT and standard laboratory analysis for both time points. A difference of 0.2 between tests at either time point was considered clinically significant based on previous literature. A paired t test was used to test for a changing or statistically significant mean difference between tests. At both time points values were categorized into absolute difference of more than 0.2 or less than 0.2, and a Fisher's exact test was used to determine if an association existed between heparin reversal and a difference more than 0.2. Bland-Altman plots were also evaluated for agreement.ResultsA statistically and clinically significant mean difference [0.09 vs. 0.25, difference-0.163 95% confidence interval (-0.25,-0.08), P = 0.003] was seen between the laboratory and POC tests when pre and postheparin reversal samples were compared. A significantly greater number of patients had a clinically relevant difference between the tests post compared with pre (four patients vs. 18 patients, P = 0.001). Linear regression analysis of the difference compared with the means, showed significant correlation suggesting the presence of a proportional bias (pre r = 0.488, P = <0.01, post r = 0.571, P = <0.01).ConclusionClinically significant differences exist between POC and laboratory testing of international normalized ratio after heparin reversal during cardiac surgery. ClinicalTrials.gov Identifier NCT03267823.

Original languageEnglish (US)
Pages (from-to)140-144
Number of pages5
JournalBlood Coagulation and Fibrinolysis
Volume31
Issue number2
DOIs
StatePublished - Mar 1 2020

Keywords

  • cardiac surgery
  • coagulation
  • international normalized ratio
  • point-of-care

ASJC Scopus subject areas

  • Hematology

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