Table 4.
Screening accuracy of pre-bronchodilator lung monitor FEV1/FEV6 cut-points, against post-BD confirmatory spirometry (FEV1/FVC < LLN).
| TP | FP | TN | FN | Sens (95% CI) | Spec (95% CI) | PPV (3% prevalence) | PPV (6% prevalence) | PPV (10% prevalence) | Proportion referred to diagnostic testa | Proportion of true cases misseda | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| <0.4 | 6 | 0 | 207 | 331 | 1.79 (0.7, 3.8) | 100 (98.2, 100) | — | — | — | 1.1% | 98.2% |
| <0.5 | 34 | 0 | 207 | 303 | 10.1 (7.1, 13.8) | 100 (98.2, 100) | — | — | — | 6.3% | 89.9% |
| <0.6 | 88 | 1 | 206 | 249 | 26.1 (21.5, 31.1) | 99.5 (97.3, 100) | 0.63 (0.19, 0.92) | 0.78 (0.33, 0.96) | 0.86 (0.46, 0.98) | 16.4% | 73.9% |
| <0.7 | 197 | 3 | 204 | 140 | 58.5 (53.0, 63.8) | 98.6 (95.8, 99.7) | 0.56 (0.39, 0.70) | 0.72 (0.57, 0.83) | 0.82 (0.70, 0.90) | 36.8% | 41.5% |
| <0.71 | 207 | 4 | 203 | 130 | 61.4 (56.0, 66.6) | 98.1 (95.1, 99.5) | 0.50 (0.38, 0.61) | 0.67 (0.56, 0.77) | 0.78 (0.69, 0.85) | 38.8% | 38.6% |
| <0.72 | 220 | 7 | 200 | 117 | 65.3 (59.9, 70.4) | 96.6 (93.2, 98.6) | 0.37 (0.31, 0.44) | 0.55 (0.48, 0.62) | 0.68 (0.62, 0.74) | 41.7% | 34.7% |
| <0.73 | 234 | 9 | 198 | 103 | 69.4 (64.2, 74.3) | 95.7 (91.9, 98.0) | 0.33 (0.29, 0.38) | 0.50 (0.45, 0.56) | 0.64 (0.59, 0.69) | 44.7% | 30.6% |
| <0.74 | 244 | 12 | 195 | 93 | 72.4 (67.3, 77.1) | 94.2 (90.1, 97.0) | 0.28 (0.25, 0.31) | 0.44 (0.41, 0.48) | 0.58 (0.54, 0.62) | 47.1% | 27.6% |
| <0.75 | 253 | 17 | 190 | 84 | 75.1 (70.1, 79.6) | 91.8 (87.2, 95.1) | 0.22 (0.20, 0.24) | 0.37 (0.34, 0.39) | 0.50 (0.48, 0.53) | 49.6% | 24.9% |
| <0.76 | 264 | 25 | 182 | 73 | 78.3 (73.6, 82.6) | 87.9 (82.7, 92.0) | 0.17 (0.16, 0.18) | 0.29 (0.28, 0.31) | 0.42 (0.40, 0.44) | 53.1% | 21.7% |
| <0.77 | 273 | 29 | 178 | 64 | 81.0 (76.4, 85.1) | 86.0 (80.5, 90.4) | 0.15 (0.14, 0.16) | 0.27 (0.26, 0.28) | 0.39 (0.38, 0.41) | 55.5% | 19.0% |
| <0.78 | 279 | 31 | 176 | 58 | 82.8 (78.3, 86.7) | 85.0 (79.4, 89.6) | 0.15 (0.14, 0.15) | 0.26 (0.25, 0.27) | 0.38 (0.37, 0.39) | 57.0% | 17.2% |
| <0.79 | 287 | 41 | 166 | 50 | 85.2 (80.9, 88.8) | 80.2 (74.1, 85.4) | 0.12 (0.11, 0.12) | 0.22 (0.21, 0.22) | 0.32 (0.31, 0.33) | 60.3% | 14.8% |
| <0.8 | 295 | 48 | 159 | 42 | 87.5 (83.5, 90.9) | 76.8 (70.5, 82.4) | 0.10 (0.10, 0.11) | 0.19 (0.19, 0.20) | 0.30 (0.29, 0.30) | 63.1% | 12.5% |
| <0.9 | 333 | 182 | 25 | 4 | 98.8 (97.0, 99.7) | 12.1 (8.0, 17.3) | 0.03 (0.03, 0.03) | 0.07 (0.07, 0.07) | 0.11 (0.11, 0.11) | 94.7% | 1.2% |
TP true positives, FP false positives, TN true negatives, FN false negatives, Sens sensitivity, Spec specificity, PPV positive predictive value
aAssuming 6% COPD prevalence