Prognostic value of marginal decline(5–10% change) and significant decline (>10% change) in forced vital capacity (FVC) in idiopathic pulmonary fibrosis (n = 84), based on the sensitivity and specificity of these thresholds for death within 1 and 2 yrs
| FVC decline | 12 months | 24 months |
| 5% threshold | ||
| Sensitivity | 83 (63–95); 15/18 | 65 (51–78); 28/43 |
| Specificity | 61 (49–72); 40/66 | 72 (57–84); 28/39 |
| PPV | 37 (23–52); 15/41 | 72 (57–84); 28/39 |
| NPV | 93 (83–98); 40/43 | 65 (50–78); 28/43 |
| LR | 2.12 (1.47–3.04) | 2.31 (1.34–3.99) |
| 10% threshold | ||
| Sensitivity | 67 (45–85); 12/18 | 37 (24–52); 16/43 |
| Specificity | 85 (75–92); 56/66 | 85 (71–94); 33/39 |
| PPV | 55 (35–73); 12/22 | 73 (53–88%); 16/22 |
| NPV | 90 (81–96); 56/62 | 55 (43–67%); 33/60 |
| LR | 4.4 (2.28–8.49) | 2.42 (1.05–5.56) |
Data are presented as % (95% CI); proportion of patients. Likelihood ratio (LR) data are are presented as % (95% CI). PPV: positive predictive value; NPV: negative predictive value. The prognostic advantage of marginal change lay in increased sensitivity, particularly for death within 2 yrs. Predictive values and LRs are shown for comparison.