Mean international normalised ratio (INR) and interlaboratory variation (CV) in two separate external quality assessment surveys. INR values were calculated and reported by each participating laboratory
| Sample A not illuminated | Sample B not illuminated | Sample C illuminated | |||||
|---|---|---|---|---|---|---|---|
| Reagent | n | Mean | CV (%) | Mean | CV (%) | Mean | CV (%) |
| The artificial blood samples were prepared separately for each survey. Artificial blood sample A was prepared from pooled coumarin plasma without addition of methylene blue and without illumination. Blood sample B was prepared from the same pooled coumarin plasma but with addition of methylene blue and without illumination. Blood sample C was prepared from the same pooled coumarin plasma but with the addition of methylene blue and with illumination. | |||||||
| n, number of laboratories. | |||||||
| Thrombotest | 41 | 3.11 | 4.6 | 3.11 | 4.9 | 3.13 | 4.5 |
| Thrombotest | 40 | 2.87 | 4.3 | 2.89 | 4.3 | 2.93 | 4.3 |
| Recombiplastin | 18 | 3.55 | 8.5 | 3.52 | 8.0 | 3.75 | 8.4 |
| Recombiplastin | 19 | 3.34 | 8.0 | 3.38 | 7.0 | 3.71 | 7.5 |
| PT-Fib HS | 17 | 3.73 | 12.0 | 3.79 | 11.9 | 4.24 | 13.9 |
| PT-Fib HS | 19 | 3.57 | 12.0 | 3.64 | 10.9 | 4.16 | 14.0 |
| Thromborel-S | 13 | 3.70 | 4.6 | 3.69 | 5.6 | 3.92 | 5.7 |
| Thromborel-S | 12 | 3.56 | 6.8 | 3.62 | 7.1 | 3.90 | 7.6 |
| Hepato Quick | 16 | 3.10 | 5.7 | 3.10 | 6.3 | 3.35 | 7.1 |
| Hepato Quick | 16 | 3.12 | 5.6 | 3.15 | 5.2 | 3.36 | 5.1 |