Table II.
Stratified comparison of lactate value by Blood Gas Analyser (BGA) with lactate value by Autoanalyser (AA) (n=50)
| Lactate | Lactate (Autoanalyser), n (%) |
Weighted Kappa |
|||||
|---|---|---|---|---|---|---|---|
| ≤2 mmol/L | 2-4 mmol/L | >4 mmol/L | Total | k | P value | ||
| Lactate (Blood gas analyser) | ≤2 mmol/L | 23 (46) | 4 (8) | 1 (2) | 28 (56) | 0.827 | <0.001 |
| 2-4 mmol/L | 4 (8) | 8 (16) | 3 (6) | 15 (30) | |||
| >4 mmol/L | 0 (0) | 1 (2) | 6 (12) | 7 (14) | |||
| Total | 27 (54) | 13 (26) | 10 (20) | 50 (100) | |||
Samples measured by each method were categorised into three clinically relevant ranges, less than or equal to 2, 2-4 and greater than 4 mmol/L and the number of samples falling into each category by both methods were recorded. The dark blue cells on the diagonal represent the number of paired samples where lactate values fell into the same category by both BGA and AA. The light blue cells represent the number of paired samples where lactate values fall into different categories by BGA and AA. Adding frequencies of the dark blue cells shows that BGA and AA showed agreement in 76% cases, and this agreement was statistically significant