THU0415 Anti-pm/scl antibody clinical associations in patients with systemic sclerosis. analysis of the multicenter eustar cohort
Authors: M.G. Lazzaroni, A. Furloni, I. Cavazzana, S. Zingarelli, F. Franceschini, A. Tincani, S. Bellando-Randone, C. Caimmi, E. Hachulla, Y. Allanore, P. Airo’
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Antibodies to the PM/Scl complex are found in patients with Systemic Sclerosis (SSc), but also with Polymyositis, Dermatomyositis and overlap syndromes. Historically, the main clinical association of anti-PM/Scl antibodies in SSc, which include calcinosis, articular and muscle involvement, and interstitial lung diseases, were described by some large single-centre studies, or by multicenter studies which recruited a relatively small number of positive patients. Therefore, some unresolved issue deserves further research. In particular, scleroderma renal crisis was recently identified in a sizeable number of anti-PM/Scl+SSc patients in a large monocentric British cohort (4 out of 70; 5.7%), a somewhat unexpected finding since this antibody type is generally considered not to be associated with renal crisis.<sup>1</sup> <h3>Objectives</h3> To evaluate clinical associations of anti-PM/Scl in patients with SSc in the large multicenter EUSTAR database, with specific focus on scleroderma renal crisis. <h3>Methods</h3> Patients from the EUSTAR database were included when the item anti-PM/Scl was fulfilled in at least one visit; clinical data were collected from the last visit available. <h3>Results</h3> Anti-PM/Scl status was available in 8,287 SSc patients from EUSTAR database: 295 were anti-PM/Scl +. After exclusion of 145 patients with multiple autoantibody positivity, 150 anti-PM/Scl+patients were compared with 7992 anti-PM/Scl -negative patients. Among these, 2530 were positive for anticentromere, 1933 for anti-topoisomerase I, 186 for anti-RNA polymerase III, and 220 for anti-U1Rnp antibodies. Renal crisis was identified in 8 of 150 anti-PM/Scl+SSc patients (5.3%), and was significantly more frequent than in anti-PM/Scl-negative SSc patients (1.6%; p=0.0015). Positivity for anti-PM/Scl was also associated with male sex, diffuse cutaneous subsets, joint and muscle involvement, lung fibrosis at chest X-rays, heart conduction blocks, stomach and intestinal symptoms (table 1). However, in multivariate analysis, adjusted for age at disease onset, sex, and disease duration, the association of anti-PM/Scl with renal crisis was not significant, whereas the associations with joint and muscle involvement, lung fibrosis, and intestinal symptoms were confirmed (table 1). <b>Table 1</b> Results of the univariable and multivariable analysis adjusted on sex, age at disease onset and disease duration (n=8142 patients). Results are presented as number/number available data (%) unless stated otherwise. <h3>Conclusions</h3> In the largest series of anti-PM-Scl positive patients so far reported, well-known clinical associations were confirmed. Moreover, scleroderma renal crisis was more frequent than in the antibody-negative patient controls (which included a majority of anticentromere-positive patients, and a relatively small number of anti-RNA polymerase III-positive patients). However, this association was probably explained by covariates, such as joint and muscle involvement, or lung fibrosis. A possible role of corticosteroid therapy might therefore be suspected. <h3>Reference</h3> [1] Bruni C, et al. Rheumatology (Oxford). 2017;56:317–8. <h3>Acknowledgements</h3> Authors would like to thank the non-profit organisation ‘Gruppo Italiano Lotta alla Sclerodermia’ (GILS) for its substantial grant for this research project. <h3>Disclosure of Interest</h3> None declared