Table 3 Dmin scenario estimated mean and 95% confidence intervals of the sensitivity and specificity of a diagnostic test, given the test achieved 97% sensitivity and 99% specificity in the evaluation sample (Dmin), for a simulated population size of 5,000, where the evaluation sample sizes correspond to current guidelines
Evaluation sample size | Sensitivity | Specificity | ||||||
|---|---|---|---|---|---|---|---|---|
Positive (e+) /negative (e−) | Mean | 95% CI | Failure (%) | Mean | 95% CI | Failure (%) | ||
Theoretical | ||||||||
30/30 | 96.9% | 88.8% | 99.9% | 10.5% | 96.9% | 88.8% | 99.9% | 38.9% |
150/250 | 96.7% | 93.4% | 98.9% | 1.7% | 98.8% | 97.2% | 99.8% | 1.9% |
250/1000 | 96.8% | 94.3% | 98.6% | 0.3% | 99.0% | 98.5% | 99.3% | 0.0% |
Prevalence: 1% | ||||||||
30/30 | 96.9% | 86.5% | 100.0% | 13.5% | 96.9% | 88.8% | 99.9% | 39.5% |
150/250 | 96.8% | 89.8% | 100.0% | 10.7% | 98.8% | 97.1% | 99.8% | 2.1% |
250/1000 | 96.8% | 90.4% | 100.0% | 9.6% | 98.9% | 98.1% | 99.5% | 0.0% |
Prevalence: 5% | ||||||||
30/30 | 96.9% | 88.5% | 100.0% | 11.3% | 96.9% | 89.1% | 99.9% | 38.7% |
150/250 | 96.7% | 92.5% | 99.6% | 3.7% | 98.8% | 97.1% | 99.8% | 2.2% |
250/1000 | 96.8% | 93.1% | 99.2% | 2.3% | 98.9% | 98.1% | 99.5% | 0.0% |
Prevalence: 10% | ||||||||
30/30 | 96.9% | 88.5% | 100.0% | 10.7% | 96.9% | 88.9% | 99.9% | 39.1% |
150/250 | 96.7% | 92.8% | 99.2% | 2.9% | 98.8% | 97.1% | 99.8% | 2.0% |
250/1000 | 96.8% | 93.7% | 99.0% | 0.9% | 98.9% | 98.1% | 99.5% | 0.0% |
Prevalence: 15% | ||||||||
30/30 | 96.9% | 88.5% | 100.0% | 11.1% | 96.9% | 88.8% | 99.9% | 39.5% |
150/250 | 96.7% | 93.1% | 99.1% | 2.3% | 98.8% | 97.1% | 99.8% | 2.3% |
250/1000 | 96.8% | 93.9% | 98.9% | 0.6% | 98.9% | 98.1% | 99.5% | 0.0% |