Discrimination and accuracy of FEV1/FVC cutoffs in detecting emphysema and gas trapping
| Sensitivity (%) (95% CI) | Specificity (%) (95% CI) | LR (95% CI) | Agreement | ||||
|---|---|---|---|---|---|---|---|
| Positive | Negative | Overall | Positive | Negative | |||
| Emphysema at least 10% (prevalence=18%) | |||||||
| Fixed | 94 (92.6 to 95.2) | 69.6 (68.4 to 70.8) | 3.1 (3 to 3.16) | 0.09 (0.07 to 0.11) | 0.74 | 0.56 | 0.81 |
| LLN | 89.9 (88.2 to 91.4) | 77.1 (76.0 to 78.1) | 3.92 (3.79 to 4.04) | 0.13 (0.11 to 0.15) | 0.79 | 0.61 | 0.86 |
| Gas trapping at least 15% (prevalence=48%) | |||||||
| Fixed | 70.2 (68.7 to 71.8) | 84.2 (83.0 to 85.4) | 4.46 (4.12 to 4.82) | 0.35 (0.33 to 0.37) | 0.77 | 0.75 | 0.79 |
| LLN | 61.2 (59.6 to 62.9) | 89.0 (87.9 to 90.0) | 5.56 (5.05 to 6.13) | 0.44 (0.42 to 0.46) | 0.76 | 0.71 | 0.79 |
FEV1, forced expiratory volume in the first second; FVC, forced vital capacity; LLN, lower limit of normal; LR, likelihood ratio.