TABLE 2.
Relative sensitivity and specificity values of EIA and LA assaya
| Sample type and analysis | Sensitivity (%) | Specificity (%) |
|---|---|---|
| Blood | ||
| Applied to same data | 81.6 | 75.4 |
| Cross-validated | 91.8 | 59.6 |
| CSF | ||
| Applied to same data | 91.2 | 93.0 |
| Cross-validated | 91.2 | 83.7 |
a
The relative sensitivity and specificity values from the sample-derived model and cross-validated model were determined using an LA assay cutoff based on a 50% chance of a positive EIA result being lower in the blood than in the CSF. Using the same data set to generate a model and assess its performance is known to overestimate its predictive ability. To account for this, we used cross-validation; one at a time, we excluded a patient, fit the best model to the remaining patients, and then assessed its accuracy on the patient who was left out.