FRI0460 The comparison between patients with systemic sclerosis, positive for for antibodies to ribonucleoprotein and classical subtypes of systemic sclerosis
Authors: R. Shayakhmetova, L. Ananieva, O. Koneva, M. Starovoitova, O. Desinova, O. Ovsyannikova, L. Garzanova
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Different clinical subtypes of systemic sclerosis (SSc) vary in frequency and severity of symptoms, progression of internal organ involvement and outcomes. The frequency of antibodies to ribonucleoprotein (RNP) in SSc varies from 5% to 30% according to reports of different studies and can be connected with separate clinical subtype of SSc. <h3>Purpose</h3> to characterise the main clinical features of patients with SSc positive for antibodies to RNP and to compare them with ACA and Scl-70 positive subtypes of SSc. <h3>Objectives</h3> to characterise the main clinical features of patients with SSc positive for antibodies to RNP and to compare them with ACA and Scl-70 positive subtypes of SSc. <h3>Methods</h3> The study included 330 patients (289 women and 41 men, mean age 50±13 years) meeting the criteria of the SSc (ACR/<sup>EULAR 2013</sup> observed between 2011 and 2017. The level of anti-nuclear antibodies was determined by ELISA. The normal level of antibodies to RNP (U1-RNP-70) was 0–25 U/ml. The level greater than 3 times the upper limit of normal considered as highly positive. <h3>Results</h3> In study group of 330 patients 49 (15%) had antibodies to ACA, 154 (46%) – to Scl-70, 67 (20%) – to RNP antibodies. Also 4 patients simultaneously had antibodies to Scl-70 and RNP, 4 patients – to ACA and RNP, 1 patient to ACA, Scl-70 and RNP. Among RNP +group 85% of patients were highly positive and 15% – low-positive. The vast majority of patients were female (91%), mean age 44,2±15 years. RNP +group was similar to ACA +group by predominance of a limited form of the disease which was 67,3% and 97% correspondingly. At the same time RNP +group was similar to Scl-70 +group by frequent involvement of internal organs – intestinal lung disease 67,3 and 69% correspondingly, involvement of cardiovascular system – 21% and 34%, esophagitis 61% and 44,5%. RNP +group had scleredema frequently – 40%, in comparison with ACA+ (10%, p&lt;0,005) and Scl-70+ (6,5%, p&lt;0,005), involvement of joints (arthralgia/arthritis) – 65% in comparison with ACA+ (24%, p&lt;0,005) and Scl-70+ (24%, p&lt;0,005), muscle weakness/pain – 43%, in comparison with ACA+ (0,2%, p&lt;0,005) and Scl-70+ (10,4%, p&lt;0,005). All 3 groups did not differ significantly by the presence of Raynauds syndrome, telangiectasia and vascular manifestations (fingertip pitting scars or digital tip ulcers). Furthermore patients with SSc highly positive for antibodies to RNP, met the criteria of mixed connective tissue diseases<sup>Kasukawa et al.,1987</sup> in 71%. <h3>Conclusions</h3> Our cogort of patients with SSc have high frequency of highly positive level of antibodies to RNP – 17%. Combination of specific SSc anti-nuclear antibodies (ACA, Scl-70) and antibodies to RNP was uncommon (2,7%) and predominantly in low-positive for antibodies to RNP patients. The distinctive features of RNP +group in contrast to the "classical" subtypes of SSc were more mild skin involvement (puffy fingers) and more severe muscle and joints involvement. Despite the limited form of the disease and mild skin involvement, RNP +group is more similar to Scl-70 +group by frequent involvement of internal organs. We propose that well known relation between skin involvement in diffuse form of SSc with Scl-70 +and organ damage is not so evident in RNP +group of SSc. <h3>Disclosure of Interest</h3> None declared