Cardiopulmonary Disease Development in Anti-RNA Polymerase III-positive Systemic Sclerosis: Comparative Analyses from an Unselected, Prospective Patient Cohort

Abstract

OBJECTIVE: Extensive skin disease and renal crisis are hallmarks of anti-RNA polymerase III (RNAP)-positive systemic sclerosis (SSc), while lung and heart involvement data are conflicting. Here, the aims were to perform time-course analyses of interstitial lung disease (ILD) and pulmonary hypertension (PH) in the RNAP subset of a prospective unselected SSc cohort and to use the other autoantibody subsets as comparators. METHODS: The study cohort included 279 patients with SSc from the observational Oslo University Hospital cohort with complete data on (1) SSc-related autoantibodies, (2) paired, serial analyses of lung function and fibrosis by computed tomography, and (3) PH verified by right heart catheterization. RESULTS: RNAP was positive in 33 patients (12%), 79% of which had diffuse cutaneous SSc. Pulmonary findings were heterogeneous; 49% had no signs of fibrosis while 18% had > 20% fibrosis at followup. Forced vital capacity at followup was < 80% in 39% of the RNAP subset, comparable to the antitopoisomerase subset (ATA; 47%), but higher than anticentromere (ACA; 13%). Accumulated frequency of PH in the RNAP subset (12%) was lower than in ACA (18%). At 93% and 78%, the 5- and 10-year survival rates in RNAP were comparable to the ATA and ACA subsets. CONCLUSION: In this cohort, the RNAP subset was marked by cardiopulmonary heterogeneity, ranging from mild ILD to development of severe ILD in 18%, and PH development in 12%. These data indicate that cardiopulmonary risk stratification early in the disease course is particularly important in RNAP-positive SSc.