%0 Journal Article %A C. J. Zappala %A P. I. Latsi %A A. G. Nicholson %A T. V. Colby %A D. Cramer %A E. A. Renzoni %A D. M. Hansell %A R. M. du Bois %A A. U. Wells %T Marginal decline in forced vital capacity is associated with a poor outcome in idiopathic pulmonary fibrosis %D 2010 %R 10.1183/09031936.00155108 %J European Respiratory Journal %P 830-836 %V 35 %N 4 %X 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 (n = 84) and NSIP (n = 72), 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; p = 0.01) 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, 95% CI 1.19–4.60; p = 0.01). 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. %U https://erj.ersjournals.com/content/erj/35/4/830.full.pdf