Table 4 Selected outcomes from applying 1- and 2-test diagnostic strategy models to four HCV epidemic scenarios. The examples here have been extracted from Additional file 2
Population: 10,000 | |||||||
|---|---|---|---|---|---|---|---|
Strategy | Anti-HCV Test Kit | True Positive | False Positive | False Negative | PPV | number of assay B tests | |
Scenario 1 Prevalence 40%: | 1-test | 2 | 3920 | 60 | 80 | 0.985 | |
2-test | 2 → 5 | 3842 | 1 | 158 | 1.000 | 3980 | |
1-test | 3 | 3980 | 120 | 20 | 0.971 | ||
2-test | 3 → 4 | 3383 | 1 | 617 | 1.000 | 4100 | |
Scenario 2 Prevalence 10%: | 1-test | 2 | 980 | 90 | 20 | 0.916 | |
2-test | 2 → 5 | 960 | 2 | 40 | 0.998 | 1070 | |
1-test | 3 | 995 | 180 | 5 | 0.847 | ||
2-test | 3 → 4 | 846 | 2 | 154 | 0.998 | 1175 | |
Scenario 3 Prevalence 2%: | 1-test | 2 | 196 | 98 | 4 | 0.667 | |
2-test | 2 → 5 | 192 | 2 | 8 | 0.990 | 294 | |
1-test | 3 | 199 | 196 | 1 | 0.504 | ||
2-test | 3 → 4 | 169 | 2 | 31 | 0.989 | 395 | |
Scenario 4 Prevalence 0.4% | 1-test | 2 | 39 | 100 | 1 | 0.282 | |
2-test | 2 → 5 | 38 | 2 | 2 | 0.951 | 139 | |
1-test | 3 | 40 | 199 | 0 | 0.167 | ||
2-test | 3 → 4 | 34 | 2 | 6 | 0.944 | 239 | |
Test Kit Performance Characteristics: | |||||||
Test Kits | Sensitivity | Specificity | Test Kits | Sensitivity | Specificity | ||
2 | 98.0% | 99.0% | 4 | 85.0% | 99.0% | ||
3 | 99.5% | 98.0% | 5 | 98.0% | 98.0% | ||
Notes on Two-Test Strategies: | |||||||
Assay B performance is considered independent of Assay A | |||||||
Outcome of 2-test strategy: A + B+ = pos and A-, A + B- = neg (Fig. 2) | |||||||
2-test strategies overall performance: | Assay A | Assay B | Sensitivity | Specificity | |||
2 | 5 | 96.04% | 99.98% | ||||
3 | 4 | 84.58% | 99.98% | ||||