Significance of pulmonary involvement in systemic sclerosis (SSc)– data from the German SSc-network

Abstract

Background: Pulmonary involvement is the leading cause of death in SSc and can manifest as interstitial lung disease (ILD), pulmonary hypertension (PAH) or a combination (ILD-PH). Aim of this analysis was to determine prevalence, clinical characteristics and outcomes of these different forms within the German SSc Network. Methods: SSc pts were analyzed for pulmonary involvement, clinical characteristics and outcome. Results: There were 3699 pts in 42 centers with a mean follow up time of 34.4±12.6 months. At baseline, ILD was frequent (29.5%), while ILD-PH and PAH had lower prevalence (7.5%, 6.1%). At the end of follow up, 32% of SSc pts had ILD, 13% ILD-PH and 7% PAH. ILD and ILD-PH were more frequent in the diffuse form (47%, 12%), while PAH did not differ between subforms. Significant differences in baseline characteristics between PAH vs. ILD-PH vs. ILD were found for age (62, 59, 54 years), sex (males: 15%, 22%, 24%) and smoking prevalence (non-smokers 49%, 63%, 57%). Mean DLCO and FVC were 56% / 93 % for PAH, 49% / 78% for ILD-PH and 56% / 81% for ILD. Significant decreases for DLCO (≥15%) and FVC (≥10%) were found in 45% / 26% in PAH, 45% / 26% for ILD-PH and 36% / 16% in ILD. All-cause mortality was 8.1% for the total cohort and differed significantly between patients without pulmonary involvement (4%), ILD (7.8%), PAH (14.2%), and ILD-PH (21%, p Conclusions: ILD is the most prevalent pulmonary involvement in SSc, while PH-ILD is associated with the most detrimental survival. Significant differences in baseline characteristics of types of pulmonary SSc involvement may help identify patients at risk in the future.