Table 4.
Cut-points of mean CT to rule-out smear positivity (with varying degrees of sensitivity).
| CT cut-off | Sensitivity % (95% CI) | Specificity % (95% CI) | Positive LR (95% CI) | Negative LR (95% CI) | Correctly classified % (95% CI) | |
|---|---|---|---|---|---|---|
| Cut-off for 99% sensitivity | ||||||
| Overall (n = 700) | 32.6 | 99.0 (97.6–99.7) | 15.6 (11.1–21.1) | 1.17 (1.11–1.24) | 0.07 (0.03–0.17) | 73.0 (69.6–79.3) |
| HIV negative (n = 293) | 29.6 | 99.1 (96.9–99.9) | 31.7 (20.3–45.0) | 1.45 (1.22–17.2) | 0.03 (0.01–0.11) | 85.3 (80.8–89.2) |
| HIV positive (n = 391) | 32.9 | 99.2 (97.0–99.9) | 11.6 (7.0–17.7) | 1.12 (1.06–1.19) | 0.07 (0.02–0.31) | 64.5 (59.5–69.2) |
| Cut-off for 95% sensitivity | ||||||
| Overall | 28.0 | 95.0 (92.7–96.8) | 54.1 (47.3–60.9) | 2.07 (1.79–2.40) | 0.09 (0.06–0.14) | 82.3 (79.3–85.0) |
| HIV negative (n = 293) | 27.3 | 95.3 (91.7–97.6) | 48.3 (35.2–61.6) | 1.84 (1.44–2.36) | 0.10 (0.05–0.18) | 85.7 (81.1–89.5) |
| HIV positive (n = 391) | 29.2 | 95.3 (91.8–97.7) | 47.7 (39.7–55.9) | 1.82 (1.57–2.13) | 0.10 (0.05–0.18) | 76.5 (72.0–80.6) |
| Cut-off for 90% sensitivity | ||||||
| Overall | 26.3 | 90.3 (87.2–92.8) | 65.1 (58.4–71.5) | 2.59 (2.15–3.11) | 0.15 (0.11–0.20) | 82.4 (79.4–85.2) |
| HIV negative (n = 293) | 25.2 | 90.1 (85.6–93.6) | 66.7 (53.3–78.3) | 2.70 (1.89–3.88) | 0.15 (0.10–0.23) | 85.3 (80.8–89.2) |
| HIV positive (n = 391) | 27.1 | 90.3 (85.7–93.7) | 64.5 (56.4–72.0) | 2.54 (2.05–3.16) | 0.15 (0.10–0.23) | 80.1 (75.7–83.9) |
| Cut-off for 85% sensitivity | ||||||
| Overall | 24.6 | 85.1 (81.6–88.1) | 72.0 (65.6–77.9) | 3.04 (2.45–3.77) | 0.21 (0.17–0.26) | 81.0 (77.9–83.8) |
| HIV negative (n = 293) | 23.5 | 85.0 (79.7–89.3) | 73.3 (60.3–83.9) | 3.18 (2.09–4.86) | 0.20 (0.15–0.29) | 82.6 (77.8–86.8) |
| HIV positive (n = 391) | 25.6 | 85.6 (80.5–89.8) | 71.6 (63.8–78.6) | 3.01 (2.34–3.89) | 0.20 (0.15–0.28) | 80.1 (75.7–83.9) |
Sensitivity, specificity, positive likelihood ratio (LR), negative LR and percentage of results correctly classified reported according to overall results (n = 700), HIV negative participants (n = 293) and HIV positive participants (n = 391).