Table 3.
Accuracy for spirometry measures to discriminate restrictive lung function (TLC < LLN)
| Parameter | Sensitivity (%) | Specificity (%) | AUROC (95% CI) | p |
|---|---|---|---|---|
| FVC Z‐score (cut‐off −1.0) | 87.5 | 79.1 | 0.904 (0.867–0.941) | <0.001 |
| FVC% of predicted (cut‐off 85.5%) | 90.6 | 81.7 | 0.900 (0.863–0.937) | <0.001 |
| FEV1 Z‐score (cut‐off −0.98) | 81.3 | 71.8 | 0.814 (0.755–0.872) | <0.001 |
| FEV1% of predicted (cut‐off 87.5%) | 81.3 | 71.0 | 0.812 (0.754–0.870) | <0.001 |
| FEV1/FVC (cut‐off 79.3%) | 65.6 | 52.9 | 0.597 (0.505–0.689) | 0.064 |
| FEV1/FVC Z‐score (cut‐off −0.457) | 71.9 | 39.8 | 0.615 (0.519–0.710) | 0.029 |
Note: The optimal cut‐off values, sensitivity and specificity for respective parameter are defined by Youden's method (i.e., highest Youden's index).
Abbreviations: AUROC, area under the ROC curve; CI, confidence interval; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; LLN, lower limit of normal; RSP, restrictive spirometry pattern; TLC, total lung capacity; Z‐score, standardized residual.