Short term pulmonary function trends are predictive of mortality in interstitial lung disease associated with systemic sclerosis.

Abstract

OBJECTIVE: To determine the prognostic value of pulmonary function test (PFT) trends at one and two years in interstitial lung disease associated with systemic sclerosis (SSc-ILD). METHODS: The prognostic significance of PFT trends at one year (n=162), and two years (n=140) was examined against 15 year survival. PFT trends, expressed as continuous and categorical change in separate analyses, were examined against mortality in univariate and multivariate models. SSc-ILD was defined at presentation as limited lung fibrosis or extensive lung fibrosis using the UKRSA staging system. RESULTS: One year PFT trends were predictive of mortality only in patients with extensive lung fibrosis: categorical FVC change, alone or in combination with categorical change in DLco, had greater prognostic significance than continuous FVC change or trends in other PFT variables. Taking into account both prognostic value and sensitivity to change, the optimal definition of progression for trial purposes was an FVC and DLco composite, consisting of either an FVC decline from baseline ≥10% or an FVC decline of 5-9% in association with a DLco decline of ≥15%. At two years, gas transfer trends had the greatest prognostic significance, in the whole cohort and in limited lung fibrosis. However, in extensive lung fibrosis, the composite end-point defined above was the strongest prognostic determinant. Larger changes were required in the FVC/DLco ratio than in Kco to achieve prognostic significance. CONCLUSION: Our findings provide support for routine spirometric and gas transfer monitoring in SSc-ILD, based on linkages to long-term outcome, with further evaluation of a composite FVC and DLco end-point warranted for trial purposes. This article is protected by copyright. All rights reserved.