Comparison of the diagnostic criteria for progressive pulmonary fibrosis in connective tissue disease related interstitial lung disease

Progressive pulmonary fibrosis (PPF) is possible among patients with connective tissue disease (CTD) related interstitial lung disease (ILD). Our aim herein was to compare the prevalence and clinical characteristics of patients with CTD-ILD, with and without PPF, according to the different diagnostic criteria currently used in practice.This retrospective study included patients diagnosed with CTD-ILD, with a ≥1-year follow-up of their lung function, at a single tertiary hospital in South Korea. Diagnostic criteria from two clinical trials (RELIEF and TRAIL1) and from a recently updated guideline (ATS/ERS/JRS/ALAT) were applied.Of the 107 patients included, 80% tested positive for Sjogren's disease, rheumatoid arthritis, and systemic sclerosis. The prevalence of CTD-ILD with PPF for the different diagnostic criteria was as follows: RELIEF, 25.2%; TRAIL1, 20.6%; and ATS/ERS/JRS/ALAT, 38.3%. More previous history of pulmonary tuberculosis and less positivity for antinuclear antibodies were identified in the PPF group. The radiologic pattern of ILD did not differ between patients with and without PPF, with a usual interstitial pneumonia pattern identified in 34.6% of the patients. Systemic steroids and immunomodulatory agents were used in about 80% of patients with PPF and 50% without PPF, irrespective of the diagnostic criteria used. Antifibrotic therapy was used in a limited number of patients in both groups.The proportion of patients with CTD-ILD and PPF was higher for the ATS/ERS/JRS/ALAT guideline criteria, without a between-group difference in clinical characteristics.