Feasibility, cost-effectiveness and patients' acceptance of point-of-care INR testing in a hospital-based anticoagulation clinic.

Point-of-care (POC) coagulometers are increasingly used by patients for self-monitoring of oral vitamin K antagonists therapy. We studied the feasibility of introducing POC international normalised ratio (INR) testing in place of standard laboratory assays in a hospital-based anticoagulation clinic with 250 active patients. The CoaguChek XS system was first validated in 253 INR samples and found to have a correlation of r = 0.945 with standard assays. Variations increased with INR readings above 3.5 and this was chosen as the cutoff for acceptance of POC INR results. POC testing was done for 1,332 clinic visits during the subsequent 6-month study. Rate of rejections of INR over 3.5 was 4.3% (95% CI 3.3-5.5%). POC testing reduced clinic visit duration by 35 min (p < 0.001, 95% CI 25-45) without cost increments to patients or the laboratory. Among 232 respondents surveyed, 87.5% (95% CI 82.5-91.5%) preferred POC INR monitoring. Rates of thrombosis and major bleeding complications were 1.2% (95% CI 0.2-3.5%) and 0.4% (95% CI 0.01-2.2%), respectively. In conclusion, provided mechanisms are in place to address increased variations of INR at higher ranges, POC testing can be successfully implemented in busy hospital-based anticoagulation clinics.