Pulmonary Function Decline in Very Early Diagnosis of Systemic Sclerosis: A Retrospective Longitudinal Single‐Center Study

OBJECTIVE: The very early diagnosis of systemic sclerosis (SSc; VEDOSS) criteria aim to identify patients at risk of evolving into SSc. The predictive value of diffusing capacity of the lungs for carbon monoxide (DLco) and forced vital capacity (FVC) remains poorly characterized. This study aimed to evaluate whether baseline pulmonary function test (PFT) alterations, especially DLco, predict progression to SSc and to examine longitudinal PFT changes in patients with stable VEDOSS over time. METHODS: A retrospective longitudinal study was conducted including 73 patients with VEDOSS. Patients were stratified by serologic, capillaroscopic, and clinical features. Annual PFT follow-up was performed at our center. Progression to SSc was defined according to the 2013 American College of Rheumatology/EULAR criteria. Kaplan-Meier curves were generated to evaluate progression rates according to baseline DLco/single breath (SB)%, using 70% as cutoff, and to evaluate time-dependent survival of both DLco% and FVC% decline according to the presence or the absence of SSc-specific antibodies (SSc-Ab), active-late nailfold videocapillaroscopic (NVC) patterns, and puffy fingers. A Cox proportional hazards regression model was used to assess the independent association between baseline DLco/SB (%) and progression-free survival, adjusting for SSc-Ab+, NVC patterns, and the presence of puffy fingers. RESULTS: Over a median follow-up of five years (maximum 11 years), 12% of patients transitioned to SSc. All progressors were SSc-Ab+ and had lower baseline DLco/SB% values (68.2% vs 81.2%, P = 0.004). A DLco/SB