Of these, 16 (6%) differed by >0

Of these, 16 (6%) differed by >0.6 INR units, four (1.6%) differed by >0.8 INR units, and one differed by >1.0 INR units. pairwise correlation analyses between samples were: for anemic patients (0.96;P< 0.001), nonanemic patients (0.93;P< 0.001), and for those obtained from arteriovenous grafts (0.94;P< 0.001). POC INR samples from dialysis catheters correlated poorly with laboratory INR results. Conclusions: POC INR correlates well with plasma INR measures in IHD patients requiring chronic warfarin, and anemia did not influence this reliability. Blood sampling from finger stick or arteriovenous graft or fistula showed excellent correlation with laboratory INR, whereas sampling from dialysis catheters Rabbit Polyclonal to SPI1 was unsatisfactory, likely from heparin contamination. Microfluidics technology for point-of-care (POC) International Normalized Ratio (INR) measurement is an established, reliable, and efficient means of monitoring patients requiring chronic warfarin therapy (15). Minimizing both the amount of blood sampled and the turnaround time for test results, POC testing has become the standard of care for chronic warfarin management strategies. Many ESRD patients on chronic intermittent hemodialysis (IHD) are anticoagulated with warfarin, which necessitates close INR monitoring. Delayed laboratory INR result availability complicates the logistics of warfarin dose management in these patients. Manufacturers of POC INR devices have specified anemia (hematocrit < 32%) as a condition in which test accuracy using this technology Pyrrolidinedithiocarbamate ammonium may suffer (6). Most IHD patients are intermittently anemic despite the routine use of hematopoietic therapy. It is therefore not clear whether POC INR testing would be suitable in the management of IHD patients on chronic warfarin therapy. To our knowledge, POC testing has not been validated in a chronic IHD population. On the basis of the existing literature, we hypothesized that POC INR testing would correlate well with plasma INR in IHD patients who are on chronic warfarin. The three main objectives of this study were: (1) to determine the correlation between POC INR and standard plasma INR (Lab INR) values in hemodialysis patients receiving chronic warfarin therapy, (2) to determine the influence of anemia on the accuracy of POC INR test results in these patients, and (3) to compare practical sites for POC INR blood sampling to confirm which were feasible and which were inappropriate. For this purpose, finger-stick blood samples for POC INR were compared with the hemodialysis access sources [indwelling central venous catheter, arteriovenous (AV) fistula, or graft] to standard dialysis INR blood sampling. Blood samples obtained from dialysis access sites that have been subject to heparin exposure including instillation to prevent catheter clotting when not in use are invalid according to technical specifications. == Materials and Methods == All chronic IHD patients receiving warfarin anticoagulation to a therapeutic goal of 2 to 3 3 or higher for at least 1 mo were approached for study participation. Mayo Foundation has two hemodialysis centers that are staffed by nurses, physicians, and practitioners working within the division of Nephrology at Mayo Clinic, Rochester. The Mayo Clinic Institutional Review Board approved this study. In this prospective comparison of paired patient data, blood samples were collected serially within 10 min immediately before hemodialysis circuit accession and heparin initiation. Each patient provided at least six sets of blood samples for INR, including the standard Pyrrolidinedithiocarbamate ammonium laboratory draw as well as POC INR samples from finger stick and from their IHD access. Serial blood samples obtained by standard finger stick and dialysis access site were analyzed immediately using the CoaguChek S device (Roche Diagnostics, Indianapolis, Indiana) (6). Dialysis access included either a central venous catheter (typically an Ash-split catheter), AV fistula, or graft. Whole blood samples (5 ml) for plasma INR assessment were collected into 3.8% sodium citrate (1:9 dilutions). Plasma INR were processed using the MDA 180 analyzer (BioMerieux, Durham, North Carolina). The thromboplastin used for INR measurements was Innovin reagent (Dade Behring Inc, Deerfield, Illinois), which has an International Sensitivity Index of 1 Pyrrolidinedithiocarbamate ammonium 1.0. During the study, warfarin dose adjustments were based on the plasma INR results. Complete blood counts were obtained at least weekly and the results of those hematocrit data were each recorded coinciding with the INR samples tested. Anemia was defined as a hematocrit < 32%. Most of the patients were intermittently treated by protocol with an erythropoietic agent and some patients required blood transfusions. == Statistical Analyses. == BlandAltman methodology was used to assess the limits of agreement and inter-reliability between POC and plasma INR values (7). Pairedttests were used to assess.