S13:6 | Investigating the intricate interplay between pulmonary functionality and advanced microangiopathy in very early diagnosis of systemic sclerosis

Eugenio Capparelli¹, Eleonora Zaccara¹, Daniela Bompane¹, Elisabetta Ricchiuto², Giorgio Bonardi², Laura Castelnovo¹, Antonio Tamburello¹, Antonino Mazzone³, Paola Faggioli¹. | ¹Rheumatology Unit; ²Pneumology Unit; ³Internal Medicine Unit, ASST Ovest Milanese, Legnano, Italy.

Background. Diffusing capacity of the lungs for carbon monoxide (DLCO) may correlate with major organ involvement, including Pulmonary Artery Hypertension (PAH), Interstitial lung Disease (ILD) and Left Ventricular Diastolic impairment in Systemic Sclerosis (SSc). Recently, the 2011 Very Early Diagnosis of Systemic Sclerosis (VEDOSS) preliminary classification criteria have been validated. Major features of VEDOSS that could predict progression toward definite SSc are represented by microvascular damage and SSc specific autoantibodies. However, Data concerning pulmonary function is still lacking in this population. The aim of our study was to detect differences between reduced versus normal values of DLCO% predicted (using a cut-off of DLCO of 80%), along with identifying several clinical predictors and to analyze the persistence of DLCO>80% in several intergroups.

Materials and Methods. A cross-sectional retrospective study was conducted by analyzing Pulmonary function tests results across a cohort of VEDOSS. Patients were enrolled due to their fulfillment of 2021 VEDOSS validated criteria, while not meeting 2013 ACR/EULAR Classification Criteria for SSc. Enrollment period spanned from September to December 2024. Clinical and demographic data were obtained from medical records. DLCO values were collected from the last available assessment, as well as nail-fold videocapillaroscopic (NVC) patterns. Tricuspid Annular Plane Systolic Excursion (TAPSE) and systolic Pulmonary Arterial Pressure (sPAP) estimates were extracted from the last echocardiographic assessment. Chi-square or Fischer exact tests and T-student were used for intergroup analysis. General univariate regression model was used to define several clinically selected determinants of reduced DLCO, by including age, body mass index, late NVC pattern, SSc specific autoantibodies positivity. Kaplan-Meyer curves and long rank test were assessed using Raynaud’s phoenomenon duration as time interval to evaluate the persistence of DLCO>80%. Statistical p was sat at <0.05.

Results. In this study, we compared clinical and demographic characteristics between patients with DLCO >80% (n=42) and DLCO<80% (n=23) [Table 1]. Patients exhibiting only Antinuclear antibody (ANA) positivity were more prevalent in the DLCO>80% group (p=0.03), while SSc-specific autoantibodies were more present in DLCO<80% group (p=0.04), as well as Gastrointestinal symptoms (p=0.03). Late NVC pattern was identified exclusively in the DLCO<80% group (p=0.01). Furthermore, notable differences were noticed also in TAPSE value, which were lower in the DLCO<80% (p<0.05) [Fig.1], no difference were reported regarding FVC% values, while FVC/DLCO% ratios were higher in DLCO reduced group. A general regression model confirmed the late NVC pattern as key predictor of reduced DLCO in VEDOSS population (p=0.013). Kaplan-Meyer analysis documented that, based on RP duration, late NVC patients presented a statistical reduced survival rate of DLCO>80% compared to early/active patients (log-rank test p<0.005) [Figure 1].

Conclusions. Reduced DLCO is also present in VEDOSS patients, and it is significantly associated with late NVC patterns and lower TAPSE values.