Validity parameters obtained for each ELISA commercial test evaluated at a 95% confidence interval (CI)
| Test | Parameter | Value (CI, 95%) |
|---|---|---|
| HIPRA1 | Sensitivity | 79.2% (62.9%, 95.4%) |
| Specificity | 100% (100%, 100%) | |
| True prevalence | 35.3% (23.9%, 46.7%) | |
| Apparent prevalence | 27.9% (17.3%, 38.6%) | |
| Youden’s J | 79.2% (62.9%, 95.4%) | |
| IDEXX2 | Sensitivity | 76.9% (60.7%, 93.1%) |
| Specificity | 100% (100%, 100%) | |
| True prevalence | 36.6% (25.4%, 47.8%) | |
| Apparent prevalence | 28.2% (17.7%, 38.6%) | |
| Youden’s J | 76.9% (60.7%, 93.1%) | |
| ID.Vet3 | Sensitivity | 84.6% (70.7%, 98.5%) |
| Specificity | 100% (100%, 100%) | |
| True prevalence | 36.6% (25.4%, 47.8%) | |
| Apparent prevalence | 31.0% (20.2%, 41.7%) | |
| Youden’s J | 84.6% (70.7%, 98.5%) | |
Distribution of the qualitative results for each ELISA test studied according to the sanitary classification of the herds
| ELISA kit | Result | True-negative herds | True-positive herds |
|---|---|---|---|
| HIPRA1 | Negative | 317 | 49 |
| Positive | 9 | 315 | |
| Doubtful | 41 | 30 | |
| IDEXX2 | Negative | 351 | 45 |
| Positive | 12 | 347 | |
| Doubtful | 4 | 2 | |
| ID.Vet3 | Negative | 359 | 43 |
| Positive | 4 | 350 | |
| Doubtful | 4 | 1 | |
Positive, negative and doubtful results yielded by the ELISA tests studied at a 95% confidence interval (CI)
| Test | Results | n (%) | CI, 95% |
|---|---|---|---|
| HIPRA1 | Negative | 366 (48.09%) | 44.56%, 51.65% |
| Positive | 324 (42.58%) | 39.11%, 46.12% | |
| Doubtful | 71 (9.33%) | 7.46%, 11.61% | |
| IDEXX2 | Negative | 396 (52.04%) | 48.49%, 55.57% |
| Positive | 359 (47.17%) | 43.65%, 50.73% | |
| Doubtful | 6 (0.79%) | 0.36%, 1.71% | |
| ID.Vet3 | Negative | 402 (52.82%) | 49.27%, 56.35% |
| Positive | 354 (46.52%) | 43.00%, 50.07% | |
| Doubtful | 5 (0.66%) | 0.28%, 1.53% | |
Distribution of the evaluation results in lactating goat sera (n = 71) for the three ELISA commercial tests studied
| Gold standard | |||
|---|---|---|---|
| ELISA test | Results | Negative(confirmed previously as n = 45) | Positive(confirmed previously as n = 26) |
| HIPRA1 | Negative | 44 | 5 |
| Positive | 0 | 19 | |
| Doubtful | 1 | 2 | |
| IDEXX2 | Negative | 45 | 6 |
| Positive | 0 | 20 | |
| Doubtful | 0 | 0 | |
| ID.Vet3 | Negative | 45 | 4 |
| Positive | 0 | 22 | |
| Doubtful | 0 | 0 | |
Agreement test between the three commercial ELISA tests studied at a 95% confidence interval (CI)
| HIPRA1/IDEXX2 | HIPRA1/ID.Vet3 | IDEXX2/ID.Vet3 | |
|---|---|---|---|
| Kappa coefficient | 0.763 | 0.762 | 0.930 |
| CI for kappa se(0) | 0.701, 0.824 | 0.701, 0.824 | 0.860, 0.999 |
| CI for kappa se(1) | 0.723, 0.803 | 0.722, 0.802 | 0.904, 0.955 |
| Observed agreement | 87.0% | 87.0% | 96.5% |
| Expected agreement | 45.2% | 45.3% | 49.4% |
| Observed agreement minus hazard | 41.8% | 41.7% | 47.0% |
| Maximum agreement not due to hazard | 54.8% | 54.7% | 50.6% |
| Concordant values | |||
| Negatives | 346 | 348 | 389 |
| Positives | 313 | 313 | 345 |
| Doubtful | 3 | 1 | 0 |
| Discordant values | 99 | 99 | 27 |
| Total studied sera | 761 | 761 | 761 |