Implications of using the prediction rule for screening for C trachomatis
| Cut off sum score* | Sensitivity† | Specificity‡ | Fraction positive¶ | PPV§ |
|---|---|---|---|---|
| *Selection criterion for screening. | ||||
| †Percentage of detected chlamydial infections among our study participants when screening under the given selection. | ||||
| ‡Percentage of chlamydia negative participants who would not be screened justly. | ||||
| ¶Percentage of the total population that is eligible for screening under the given selection. | ||||
| §Prevalence in the screened population (predictive value of selection criterion). | ||||
| ⩾0 | 100.0% | 0.0% | 100.0% | 2.3% |
| ⩾1 | 100.0% | 0.5% | 99.5% | 2.4% |
| ⩾2 | 100.0% | 2.4% | 97.7% | 2.4% |
| ⩾3 | 100.0% | 4.6% | 95.5% | 2.5% |
| ⩾4 | 99.3% | 14.4% | 85.9% | 2.7% |
| ⩾5 | 94.4% | 23.0% | 77.4% | 2.9% |
| ⩾6 | 93.1% | 38.3% | 62.4% | 3.5% |
| ⩾7 | 86.8% | 56.0% | 45.0% | 4.5% |
| ⩾8 | 79.2% | 68.4% | 32.7% | 5.7% |
| ⩾9 | 59.0% | 83.2% | 17.8% | 7.8% |
| ⩾10 | 41.7% | 92.2% | 8.6% | 11.4% |
| ⩾11 | 27.8% | 96.8% | 3.7% | 17.5% |
| ⩾12 | 11.8% | 98.9% | 1.4% | 20.5% |
| ⩾13 | 4.2% | 99.8% | 0.3% | 31.6% |
| ⩾14 | 1.4% | 99.9% | 0.1% | 25.0% |