Lung function decline in sarcoidosis

BackgroundA decline in lung function is the basis of the definition of progressive fibrosing interstitial lung disease. This study aimed to evaluate the epidemiology and clinical relevance of lung function decline in sarcoidosis.MethodsThis retrospective observational study was conducted at a general sarcoidosis clinic. Lung function decline was defined as a relative 24-month decline in the percentage of predicted forced vital capacity (%FVC) of ≥10% or the percentage of predicted diffusion capacity for carbon monoxide (%DLco) of ≥15%. The frequency of lung function decline and its associations with the subsequent 24-month change in lung function and survival time were analyzed.ResultsOf the 201 patients, 14 (7.0%) exhibited a 24-month decline in %FVC of ≥10% and 28 (16.6%) exhibited a 24-month decline in %DLco of ≥15%. A 24-month decline in lung function was not associated with a subsequent 24-month lung function decline. Eleven patients died during the median observational time of 148.3 months; 4 of the 11 deaths were associated with sarcoidosis. A 24-month decline in lung function was associated with worse survival even after the adjustment for composite physiological index (CPI) and pulmonary hypertension (PH): 24-month decline in %FVC ≥10%, hazard ratio (HR) adjusted for CPI = 21.8, HR adjusted for PH = 19.3 and 24-month decline in %DLco ≥15%, HR adjusted for PH = 6.74.ConclusionsA 24-month decline in lung function can be a risk factor for mortality in sarcoidosis irrespective of CPI and PH.