Use of a capillary specimen in the laboratory to verify a point‐of‐care international normalized ratio: Avoidance of a venipuncture in a pediatric setting

Point‐of‐care ( POC ) international normalized ratio ( INR ) values above an institutional cutoff are confirmed in the laboratory using a gold standard venous specimen. This can be problematic in a pediatric setting. Method In this study, 449 consecutive POC INR results were compared to an INR performed in the laboratory on a capillary citrate specimen collected from the same finger‐stick. The results were statistically analyzed. Results The mean INR values from the CoaguChek XS and laboratory were 2.85 ± 1.19 and 2.63 ± 1.11, respectively. There was a good correlation between the methods with r  = 0.97. Bland–Altman analysis indicated a bias of 0.22 favoring the CoaguChek XS , with 95% limits of agreement −0.29 to 0.72. Passing and Bablok method comparison resulted in a slope of 0.91 ( y  = 0.91 x  + 0.02). An INR of ≤0.5 was found between the methods in 89% of cases and 84% agreement was noted ( κ  = 0.69). Conclusion Comparing the capillary INR laboratory results to studies involving a venous specimen, the capillary specimen performed with equivalence. Thus, a capillary citrate specimen can be collected from the same finger‐stick used to perform the POC INR for confirmation in the laboratory. This avoids the trauma of a venous collection in such a situation.