POS1270 THE IMPACT OF OVERLAP SYNDROMES ON THE SCLERODERMA CLINICAL TRIAL CONSORTIUM DAMAGE INDEX (SCTC-DI) IN SYSTEMIC SCLEROSIS

Abstract

BackgroundSystemic sclerosis (SSc) is a systemic autoimmune disease leading to tissue atrophy, vascular damage and organ failures, and therefore causing severe disability. Coexistent autoimmune diseases are called overlap syndromes. Due to the distinct clinical picture[1], the extent of damage in SSc-overlap may be affected compared to pure-SSc.ObjectivesTo identify differences in the time course and characteristics of damage between pure-SSc and SSc-overlap patients by evaluating the Scleroderma Clinical Trials Consortium-Damage Index (SCTC-DI)[2].MethodsSingle tertiary care centre observational study with 160 enrolled SSc patients. Eighty-eight patients (55%) had diffuse cutaneous SSc (dcSSc), 86% were female and median disease duration was 9 years/4;16/. SSc-overlap was diagnosed based on the evaluation of the attending physicians. SCTC-DI was calculated. SCTC-DI score between 6-12 was considered as moderate and >12 points as severe damage. Damage profile of pure-SSc and SSc-overlap including subsets was compared.ResultsSSc-overlap was present in 24% of cases (n=39; 18 rheumatoid arthritis, 12 Sjögren, 12 myositis, 1 antiphospholipid syndrome). Age at enrolment and at disease onset, dcSSc/limited cutaneous (lcSSc) ratio, disease duration and gender distribution showed no difference between pure-SSc and SSc-overlap. Pure-SSc and SSc-overlap patients, including lcSSc/dcSSc subset comparison had the same damage burden (Kruskal-Wallis p>0.05). Median/IQR/ SCTC-DI was similar in pure-SSc and SSc-overlap (9/7;14/ and 9/6;13/ respectively). Moderate damage was found in around 53% and severe damage in 28% of patients in both pure-SSc and SSc-overlap. Gastrointestinal, cardiopulmonary, cardiac, vascular and renal domains of SCTC-DI did not differ between SSc-overlap and pure-SSc, whereas proximal muscle weakness was more prevalent in SSc-overlap compared to pure-SSc. ILD was scored similarly frequently in pure-dcSSc and dcSSc-overlap (82% vs 66.7%, χ² p>0.05), however, it was also present in 65% of pure-lcSSc and 60% of lcSSc-overlap patients. Severe damage was more prevalent in SSc-overlap patients at early stage of SSc (≤3 years duration, Fisher’s p=0.029) compared to pure-SSc. Early severe damage was more frequent in dcSSc-overlap compared to pure-dcSSc (Fisher’s p=0.042). Although in pure-SSc there were weak—to-moderate correlations between the SCTC-DI, age, and disease duration (Spearman’s rho:.360-.498;p<0.001), no such associations were found in SSc-overlap patients. Differences in SCTC-DI items in pure-SSc and SSc-overlap are shown in Table 1.Table 1.Differences in SCTC-DI items in SSc-overlap and pure-SScn (%)pure-SSc n=121SSc-overlap n=39pure-dcSSc n=67pure-lcSSc n=54dcSSc-overlap n=21lcSSc-overlap n=18Small joint CC59 (48.8)21 (53.8)d41 (61.2)a18 (33.3)14 (66.7)7 (38.9)Large joint CC46 (38.0)19 (48.7)d32 (47.8)a14 (25.9)11 (52.4)8 (44.4)Proximal muscle weakness12/118 (10.2)11/38 (28.9)b, c, d8 (11.9)4/52 (7.7)7 (33.3)e,f4/17 (23.5)Digital ulcers45 (37.2)13 (33.3)31 (46.3)a14 (25.9)9 (42.9)4 (22.2)SSc-ILD76/101 (75.2)21/33 (63.6)50/61 (82)c26/40 (65)12/18 (66.7)9/15 (60)CC: contracturesBold characters: p<0.05.apure-dcSSc vs pure-lcSSc;bpure-SSc – SSc-overlap;cpure-dcSSc – SSc-overlap;dpure-lcSSc – SSc-overlap;epure-SSc – dcSSc-overlap;fpure-dcSSc – dcSSc-overlapConclusionSCTC-DI is a relevant tool to assess damage in SSc-overlap. In this cohort damage was not related to ageing and disease duration in SSc-overlap. Early dcSSc-overlap patients had higher risk to develop severe damage compared to early pure-dcSSc patients based on the SCTC-DI. Pulmonary damage was less frequent in SSc-overlap compared to pure-dcSSc, but similar in pure-dcSSc and dcSSc-overlap patients. As expected, musculoskeletal damage, especially proximal muscle weakness was present in a remarkable proportion of SSc-overlap patients.