Table 2.
Sensitivity, specificity, positive and negative predictive value as well as accuracy of nonimaging parameters to predict trapped air, with the trapped air % from spirometry-controlled computed tomography used as the gold standard and comparitor for this analysis
| Parameter | Sensitivity, % | Specificity, % | Positive Predictive Value, % | Negative Predictive Value, % | Accuracy, % |
|---|---|---|---|---|---|
| ppFEV1 | 28 | 83 | 84 | 27 | 42 |
| ppFVC | 11 | 83 | 68 | 23 | 29 |
| ppFEF25–75% | 63 | 75 | 90 | 37 | 67 |
| ppFEF75% | 61 | 50 | 81 | 26 | 58 |
| RV/TLC% | 11 | 100 | 100 | 26 | 32 |
| LCI2.5 | 47 | 100 | 100 | 38 | 60 |
| LCIShX | 63 | 100 | 100 | 46 | 72 |
| UVLU | 79 | 100 | 100 | 60 | 80 |
| 5IC VTG/VC | 47 | 100 | 100 | 25 | 55 |
| 5VC VTG/VC | 50 | 100 | 100 | 37 | 61 |
5IC, 5 inspiratory capacity breaths; 5VC, 5 vital capacity; LCI, lung clearance index; ppFEF25–75%, percent predicted forced expiratory flow at 25–75% of the forced vital capacity (FVC); FEF75%, percent predicted forced expiratory flow when 75% of FVC has been exhaled; ppFEV1, percent predicted forced expiratory volume in 1 second; ppFVC, percent predicted forced vital capacity; RV, residual volume; TLC, total lung capacity; UVLU, under-ventilated lung units; VTG, volume of trapped gas.