Table 3. Sensitivity and Specificity of the Plausible-Source Case Approach to Estimation of Tuberculosis Recent Transmission (RT) Across Distances Varying From 0 to 500 Miles (800 km) and Accuracy of Estimates Across a Range of Plausible Hypothetical RT Prevalence Rates (n = 1,085), Arkansas, Maryland, and Massachusetts, January 1, 1998–September 30, 2000.
| Distance, miles (km) | No. of True-Positive Cases | No. of False-Positive Cases | No. of True-Negative Cases | No. of False-Negative Cases | Sensitivity, % | Specificity, % | Accuracy of Estimate by Hypothetical RT Prevalence, % | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||||
| 10% | 15% | 20% | 25% | 30% | 50% | |||||||
| 0 (0) | 0 | 0 | 1,013 | 72 | 0.00 | 100.0 | 90.0 | 85.0 | 80.0 | 75.0 | 70.0 | 50.0 |
| 1 (1.6) | 39 | 19 | 994 | 33 | 54.2 | 98.1 | 93.7 | 91.5 | 89.3 | 87.1 | 84.9 | 76.2 |
| 5 (8) | 58 | 36 | 977 | 14 | 80.6 | 96.5 | 94.9 | 94.1 | 93.3 | 92.5 | 91.7 | 88.5 |
| 10 (16) | 64 | 50 | 963 | 8 | 88.9 | 95.1 | 94.4 | 94.1 | 93.8 | 93.5 | 93.2 | 92.0 |
| 20 (32) | 65 | 65 | 948 | 7 | 90.3 | 93.6 | 93.3 | 93.1 | 92.9 | 92.8 | 92.6 | 91.9 |
| 31.3 (50) | 65 | 73 | 940 | 7 | 90.3 | 92.8 | 92.5 | 92.4 | 92.3 | 92.2 | 92.0 | 91.5 |
| 50 (80) | 68 | 82 | 931 | 4 | 94.4 | 91.9 | 92.2 | 92.3 | 92.4 | 92.5 | 92.7 | 93.2 |
| 60 (96) | 68 | 84 | 929 | 4 | 94.4 | 91.7 | 92.0 | 92.1 | 92.3 | 92.4 | 92.5 | 93.1 |
| 75 (120) | 69 | 89 | 924 | 3 | 95.8 | 91.2 | 91.7 | 91.9 | 92.1 | 92.4 | 92.6 | 93.5 |
| 100 (160) | 69 | 93 | 920 | 3 | 95.8 | 90.8 | 91.3 | 91.6 | 91.8 | 92.1 | 92.3 | 93.3 |
| 200 (320) | 70 | 94 | 919 | 2 | 97.2 | 90.7 | 91.4 | 91.7 | 92.0 | 92.4 | 92.7 | 94.0 |
| 300 (480) | 70 | 97 | 916 | 2 | 97.2 | 90.4 | 91.1 | 91.4 | 91.8 | 92.1 | 92.5 | 93.8 |
| 500 (800) | 70 | 105 | 908 | 2 | 97.2 | 89.6 | 90.4 | 90.8 | 91.2 | 91.5 | 91.9 | 93.4 |
Abbreviation: RT, recent transmission.