Table 2.
Diagnostic test characteristics for STIGA in calf serum
| Cut point, OD 450 | Accuracy, % | Se, % | Sp, % | PPV, % | NPV, % |
|---|---|---|---|---|---|
| Dairy calf serum | |||||
| 0.2 | 91.6 | 77.8 | 98.2 | 95.5 | 90.2 |
| 0.3 | 86.7 | 100.0 | 80.4 | 71.1 | 100.0 |
| 0.4 | 67.5 | 100.0 | 51.8 | 50.0 | 100.0 |
| 0.5 | 55.4 | 100.0 | 33.9 | 42.2 | 100.0 |
| 0.6 | 45.8 | 100.0 | 19.6 | 37.5 | 100.0 |
| 0.7 | 41.0 | 100.0 | 12.5 | 35.5 | 100.0 |
| 0.8 | 34.9 | 100.0 | 3.6 | 33.3 | 100.0 |
| Beef calf serum | |||||
| 0.1 | 85.7 | 7.7 | 100.0 | 100.0 | 85.5 |
| 0.2 | 90.5 | 38.5 | 100.0 | 100.0 | 102.9 |
| 0.3 | 92.9 | 69.2 | 97.2 | 81.8 | 94.5 |
| 0.4 | 83.9 | 100.0 | 91.5 | 46.4 | 116.1 |
| 0.5 | 52.4 | 100.0 | 43.7 | 24.5 | 100.0 |
| 0.6 | 31.0 | 100.0 | 18.3 | 18.3 | 100.0 |
| 0.7 | 16.7 | 100.0 | 1.4 | 15.7 | 100.0 |
Accuracy, sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) calculated for OD cut points for detecting FTPI with STIGA with cut-offs of 10 mg/mL IgG for dairy calf sera and 24 mg/mL for beef calf sera determined by RID; for dairy calf sera (n = 83) and beef calf sera (n = 84)