Key result
Point-of-care INR testing showed a clinically significant mean difference compared to standard laboratory testing after heparin reversal (difference -0.163; 95% CI -0.25 to -0.08; P=0.003).
Why the study?
The study was conducted to compare point-of-care international normalized ratio measurements to laboratory-derived values before and after cardiopulmonary bypass, evaluating for changes in their relationship.
Does point-of-care INR testing provide equivalent results to standard laboratory testing before and after heparin reversal in patients undergoing cardiac surgery?
Observational (n=50)
Does point-of-care INR testing provide equivalent results to standard laboratory testing before and after heparin reversal in patients undergoing cardiac surgery?
Point-of-care INR testing shows clinically significant differences compared to standard laboratory testing after heparin reversal in cardiac surgery, indicating potential unreliability in this specific setting.
POC INR may not be interchangeable with lab testing after heparin reversal; leaves open prospective validation before clinical adoption.
STUDY OBJECTIVE: To 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. METHODS: This 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. RESULTS: A 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). CONCLUSION: Clinically significant differences exist between POC and laboratory testing of international normalized ratio after heparin reversal during cardiac surgery. ClinicalTrials.gov Identifier NCT03267823.
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Fabbro et al. (2020) conducted an observational in cardiac surgery (n=50). Point-of-care (POC) i-STAT testing vs. Standard laboratory analysis was evaluated on Mean difference between laboratory and POC tests of INR when pre and postheparin reversal samples were compared (MD -0.163, 95% CI -0.25, -0.08, p=0.003). Point-of-care INR testing showed a clinically significant mean difference compared to standard laboratory testing after heparin reversal (difference -0.163; 95% CI -0.25 to -0.08; P=0.003).
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