Table 4.
Accuracy of Reference-Adjusted Spirometry for Discriminating Respiratory Symptoms, Health Care Utilization, New-Onset Disease, and Death.*
| Outcome and Cohort | Best Spirometric Predictor | Discriminative Accuracy (95% CI)† | ||
|---|---|---|---|---|
| GLI-2012 | GLI-Global | Difference | ||
| C statistic | ||||
| Concurrent respiratory symptoms, NHANES IV | ||||
| Dyspnea on exertion | FEV1 z score | 0.634 (0.619 to 0.649) | 0.632 (0.616 to 0.647) | −0.002 (−0.009 to 0.004) |
| Wheezing that limits activity | FEV1 z score | 0.685 (0.655 to 0.714) | 0.689 (0.661 to 0.718) | 0.005 (−0.008 to 0.017) |
| Lung or breathing problem that limits activity | FEV1 z score | 0.737 (0.695 to 0.780) | 0.746 (0.705 to 0.787) | 0.009 (−0.008 to 0.025) |
| Recent health care utilization, NHANES IV | ||||
| Medical visit for wheezing in past yr | FEV1 z score | 0.676 (0.644 to 0.708) | 0.676 (0.644 to 0.707) | −0.001 (−0.013 to 0.012) |
| Overnight hospital admission in past yr | FEV1 z score | 0.573 (0.548 to 0.598) | 0.584 (0.559 to 0.609) | 0.011 (0.001 to 0.021) |
| New-onset respiratory disease, U.K. Biobank | ||||
| Asthma ≤10 yr | FEV1:FVC z score | 0.587 (0.559 to 0.616) | 0.588 (0.559 to 0.617) | 0.001 (−0.002 to 0.003) |
| COPD ≤10 yr | FEV1:FVC z score | 0.786 (0.750 to 0.823) | 0.792 (0.755 to 0.828) | 0.005 (0.002 to 0.008) |
| Death, NHANES III | ||||
| 30-yr incidence from chronic lower respiratory disease | FEV1:FVC z score | 0.838 (0.628 to 0.981) | 0.833 (0.601 to 0.981) | −0.004 (−0.037 to 0.013) |
| 10-yr incidence from any cause | FEV1 z score | 0.620 (0.530 to 0.705) | 0.620 (0.528 to 0.706) | −0.001 (−0.022 to 0.022) |
| Death while on transplant waiting list, OPTN | ||||
| 45-day incidence | FVC z score | 0.573 (0.545 to 0.598) | 0.564 (0.538 to 0.590) | −0.008 (−0.013 to −0.003) |
| 365-day incidence | FVC z score | 0.573 (0.547 to 0.599) | 0.568 (0.542 to 0.594) | −0.005 (−0.011 to 0.001) |
*
Predictors included spirometric z scores, indicating the number of standard deviations by which a measured value is above or below the predicted normal value. Results are provided for the spirometric z score with the highest mean concordance statistic (C statistic) among FEV1, FVC, and the ratio of FEV1 to FVC.
†
Harrell’s C statistics were calculated with the use of z scores derived from race-based GLI-2012 equations or race-neutral GLI-Global equations to predict respiratory outcomes.