Cardiopulmonary Exercise Testing Allows Discrimination Between Idiopathic Non-specific Interstitial Pneumonia and Idiopathic Pulmonary Fibrosis in Mild to Moderate Stages of the Disease

It is unclear whether there are cardiopulmonary exercise testing (CPET) parameters which may indicate poor prognosis in the early course of fibrosing interstitial lung disease. 27 untreated consecutive subjects (13 idiopathic non-specific interstitial pneumonia (iNSIP), 14 idiopathic pulmonary fibrosis (IPF); 19 male; age 69 ± 10 years) were enrolled in this observational pilot study. Subjects underwent routine pulmonary function testing and CPET. Statistically, the t test and the Mann–Whitney-U test were applied in the presence of normal and non-normal distribution (according to Shapiro–Wilk), respectively. Analyzing the whole cohort, only mild functional impairments were determined. Comparison of iNSIP and IPF groups detected significant differences for the CPET parameters V’O2Peak[%pred] (p = 0.011), V’O2/kgPeak (p = 0.033), Watt[%pred] (p = 0.048), V’E/V’CO2 (Rest: p = 0.016; AT: p = 0.011; Peak: p = 0.019; Slope: p = 0.040), V’E/V’O2 (Rest: p = 0.033 AT: p = 0.014; Peak: p = 0.035). CPET parameters may indicate IPF-specific impairments even in mild disease. It may be hypothesized that these parameters are early biomarkers of poor prognosis.