Background: Vascular involvement in Systemic Sclerosis (SSc) is known to start even before clinical diagnosis, to drive Digital Ulcer disease and later in the disease natural history to cause Pulmonary Artery Hypertension, among other manifestations. Despite the proven immune origin of Scleroderma, vascular involvement is not currently targeted by immune driven interventions. Similarly, little data is available on immune or inflammatory biomarkers and outcome measures of vascular disease in SSc. Digital Artery Volume Index (DAVIX) has been recently proposed as imaging surrogate outcome measure of vascular disease activity in SSc [1].

Objectives: Here we aimed to determine the value of DAVIX as overall biomarker of vascular involvement and its correlation with Type I IFN activation in patients with SSc.

Methods: Eighty-six patients attending our Scleroderma Program were consecutively enrolled for the evaluation of serum IFN score as previously described [2]. Clinical features including presence or history of Digital Ulcers, Presence of Pulmonary Artery Hypertension (PAH) and DLCO, were recorded. Digital Artery Vascular Index (DAVIX) of the dominant hand’s fingers was calculated using time of flight magnetic resonance images analysed through IAG proprietary algorithm, as previously described [1]. Medians were compared by Mann-Whitney-Wilcoxon test, correlation with clinical parameters was performed using Spearman’s or Pearson test, as appropriate (R).

Results: Sixty-two patients fulfilled the 2013 ACR/EULAR classification criteria for SSc (diffuse cutaneous 24.6%, limited cutaneous 75.4%) whereas 23 were classified as Very Early Diagnosis of Scleroderma (Criteria score between 6 and 8). Twenty-three patients had DU disease (History of DUs in the previous 24 weeks, presence of DUs at baseline assessment, or onset of new DUs during the following 24 weeks). Eighteen patients had reduced DLCO (<70) with FVC/DLCO>1.8 (suspected PAH). DAVIX showed a negative correlation with disease duration (r=-0.33 and p=.003) and with FVC/DLCO ratio (r=-0.34 and p=.009). Patients with DU disease presented lower DAVIX than patients without (p=.018).

DAVIX showed a significant correlation with Serum IFN score (r=-0.24, p<0.032). Accordingly, patients classified as IFN-HI had lower DAVIX than those within the IFN-LO group (p=0.016).

Conclusion: DAVIX correlated both with presence of Digital Ulcer disease, DLCO and disease duration. The correlation of DAVIX and Serum IFN score does support the notion of innate immune involvement in vascular disease manifestations of SSc. Prospective testing in the context of Randomised controlled trial will determine the value of DAVIX as surrogate outcome measure of vascular disease severity in SSc.

REFERENCES:

[1]Gjeloshi K, et al. Arthritis Rheumatol. 2020.

[2]Hinchcliff M et al. Arthritis Rheumatol. 2021.

Disclosure of Interests: Stefano Di Donato: None declared, Mike Hughes: None declared, Giuseppina Abignano: None declared, Giovanni Lettieri: None declared, Rebecca Ross: None declared, Enrico De Lorenzis: None declared, Philip O’Connor: None declared, Olga Kubassova Shareholder of: IAG Image Analysis Group, CEO, Francesco Del Galdo: None declared