In therapeutic studies in idiopathic pulmonary fibrosis (IPF), the low prevalence of significant change in pulmonary functional tests (PFTs) has been a major constraint. The prognostic value of ''marginal'' changes in PFTs in IPF and fibrotic non-specific interstitial pneumonia (NSIP) was evaluated.In patients with biopsy-proven IPF (n584) and NSIP (n572), forced vital capacity (FVC) and diffusing capacity of the lung for carbon monoxide (DL,CO) trends at 6 months were categorised as ''significant'' (FVC .10%; DL,CO .15%) or ''marginal'' (FVC 5-10%; DL,CO 7.5-15%). Proportional hazards analysis and time-dependent receiver operating characteristic methodology were used to examine PFT trends against mortality.In IPF, reductions in FVC were significant in 22 cases (26%) and marginal in 19 cases (23%). Mortality was higher in patients with a significant decline in FVC (hazard ratio (HR) 2.80, 95% CI 1.54-5.06; p,0.001) and those with a marginal decline in FVC (HR 2.31, 95% CI 1.19-4.50; p50.01) than in those with stable disease. Progression-free survival was lower when the decline in FVC was marginal than in stable disease (HR 2.34, p50.01). Marginal changes in DL,CO in IPF and marginal changes in FVC and DL,CO in fibrotic NSIP did not provide useful prognostic information.Marginal change in FVC in IPF denotes a poor outcome. These findings are applicable to clinical practice and to the selection of patients with more progressive disease for therapeutic studies.

Objective-A study was performed to produce reference standards for spirometric lung function in white children and to calculate standard deviation scores adjusted for gender and pubertal stage.Methods-A cross sectional study was made of 772 white children aged 4-6 to 18-8 years (455 male) tested on an OHIO 840 spirometer and assessed anthropometrically and pubertally.

In idiopathic pulmonary fibrosis, the quantitation of disease severity using pulmonary function tests is often confounded by emphysema. We have identified the composite physiologic index (CPI) most closely reflecting the morphologic extent of pulmonary fibrosis. Consecutive patients with a clinical/computed tomography (CT) diagnosis of idiopathic pulmonary fibrosis (n = 212) were divided into group I (n = 106) and group II (n = 106). The CPI was derived in group I (by fitting pulmonary function tests against disease extent on CT) and was tested in Group II. The formula for the CPI was as follows: extent of disease on CT = 91.0 - (0.65 x percent predicted diffusing capacity for carbon monoxide [DLCO]) - (0.53 x percent predicted FVC) + (0.34 x percent predicted FEV1). In group II, the CPI correlated more strongly with disease extent on CT (r2 = 0.51) than the individual pulmonary function test (DLCO the highest value, r2 = 0.38). A subanalysis demonstrated that the better fit of the CPI was ascribable to a correction of the confounding effects of emphysema. Mortality was predicted more accurately by the CPI than by a pulmonary function test in all clinical subgroups, including a separate cohort of 36 patients with histologically proven usual interstitial pneumonia (CPI, p < 0.0005; FVC, p = 0.002; PO2, p = 0.002). In conclusion, a new CPI, derived against CT and validated using split sample testing, is a more accurate prognostic determinant in usual interstitial pneumonia than an individual pulmonary function test.