Table 20 Population-level screening performance under natural prevalence conditions.
Population context | Sample size | True positive rate (95% CI) | False positive rate (95% CI) | Positive predictive value (95% CI) | Negative predictive value (95% CI) | Number needed to screen (95% CI) | Cost per detection (USD, 95% CI) | Likelihood ratio+ | p-value |
|---|---|---|---|---|---|---|---|---|---|
Rural community (high prevalence) | 15,000 | 87.3% (85.1–89.5) | 2.8% (2.1–3.5) | 73.4% (70.8–76.0) | 97.8% (97.2–98.4) | 23 (19–28) | $127 ($108-$146) | 31.2 | < 0.001 |
Urban community (moderate prevalence) | 22,000 | 84.7% (82.9–86.5) | 3.2% (2.6–3.8) | 68.9% (66.7–71.1) | 96.4% (95.9–96.9) | 31 (27–36) | $156 ($139-$173) | 26.5 | < 0.001 |
Mobile screening (variable prevalence) | 8500 | 78.9% (76.4–81.4) | 4.1% (3.3–4.9) | 58.7% (55.8–61.6) | 94.9% (94.1–95.7) | 47 (39–56) | $203 ($176-$230) | 19.2 | < 0.001 |
School-based screening (low prevalence) | 12,000 | 71.2% (68.1–74.3) | 2.6% (2.0-3.2) | 45.3% (41.8–48.8) | 98.7% (98.3–99.1) | 89 (72–108) | $298 ($259-$337) | 27.4 | < 0.001 |
Elderly population (high prevalence) | 9200 | 89.1% (87.2–91.0) | 3.7% (2.9–4.5) | 76.8% (74.1–79.5) | 96.2% (95.5–96.9) | 18 (15–22) | $109 ($92-$126) | 24.1 | < 0.001 |
International sites (mixed prevalence) | 18,400 | 82.6% (80.9–84.3) | 3.4% (2.8-4.0) | 64.2% (61.9–66.5) | 95.8% (95.3–96.3) | 38 (33–44) | $174 ($155-$193) | 24.3 | < 0.001 |
