Patients and clinical assessment
We enrolled 72 SSc patients [F=63, median age 55 years (IQR 46-65)], fulfilling the American College of Rheumatology/European League Against Rheumatism Collaborative Criteria for SSc [11]. According to Le Roy et al, 33 out of 72 Thirty-three (45.8%) showed diffuse cutaneous SSc (dcSSc) and 39 out of 72 (54.2%) limited cutaneous SSc (lcSSc) [12]. Demographic and clinical features of SSc patients are shown in Table 1. We also enrolled in the study 30 HC matched for sex and age were. Exclusion criteria were renal failure, monoclonal gammopathies and hematological malignancies, immunosuppressive therapy in the last six months, pregnancy, and breastfeeding. Informed written consent was obtained from all the participants and the study was conducted according to the Declaration of Helsinki.
Demographic and clinical features were recorded. Disease subset [12], disease duration, nailfold videocapillaroscopy (NVC) pattern (early, active, late) [13], disease activity index (DAI) [14], disease severity scale (DSS) [15] and modified Rodnan skin score (mRSS) [16] were evaluated.
In the evaluation of SSc, DAI consists of variables among which skin thickening, digital ulcers, impaired single breath carbon monoxide diffusing capacity, tendon friction rubs and C-reactive protein (CRP) while DSS measures disease severity in organ systems from general health to specific organ involvement.
Renal function was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation to estimate glomerular filtration rate (eGFR) and serum creatinine was measured [17]. Moreover, all patients had an eGFR ≥60 mL/min/1.73m2.