Table 2.
The NPV and PPV of initial ELISA results for HIV blood screening.
| HIV screening | Single ELISA kit (284) | Two different ELISA kits (745) | ELISA (1029) | ECLIA | CLIA | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Status | Nonreactive | Reactive | Dual nonreactive | Single reactive | Dual reactive | Nonreactive | Reactive | Sum | Nonreactive | Reactive | Nonreactive | Reactive |
| 183 | 101 | 395 | 200 | 150 | 578 | 451 | 1029 | 884 | 145 | 885 | 144 | |
| True negatives | 183 | 71 | 395 | 198 | 46 | 578 | 315 | 893 | 884 | 9 | 885 | 8 |
| True positives | 0 | 30 | 0 | 2 | 104 | 0 | 136 | 136 | 0 | 136 | 0 | 136 |
| NPV§ | 100% (183/183) | — | 100% (395/395) | — | — | 100% (578/578) | — | 100% (578/578) | 100% (884/884) | — | 100% (885/885) | — |
| PPV§ | — | 29.7% (30/101) | — | 1.0% (2/200) | 69.3% (104/150) | — | 30.2% (136/451) | 30.2% (136/451) | — | 93.8% (136/145) | — | 94.4% (136/144) |
§: positive predictive value (PPV) and negative predictive value (NPV) are the proportions of positive and negative results in statistics and diagnostic tests that are true positive and true negative results, respectively.