OBJECTIVE: Systemic sclerosis (SSc) patients are classified according to degree of skin fibrosis (limited and diffuse cutaneous) and serum autoantibodies. We undertook the present multicenter study to determine if intrinsic subset (IS) classification based upon skin gene expression yields additional valuable clinical information.METHODS: SSc patients and healthy participants (HP) were classified as Normal-like, Limited, Fibroproliferative and Inflammatory IS using a previously trained classifier. Clinical data were obtained (serum autoantibodies, pulmonary function testing, modified Rodnan Skin scores [mRSS], and high-resolution chest computed tomography [HRCT]). Statistical analyses were performed to compare patients classified by IS, traditional cutaneous classification, and serum autoantibodies.RESULTS: 223 participants (165 SSc [115 dcSSc and 50 lcSSc] and 58 HP) were classified. Inflammatory IS patients had higher mRSS (22.1±9.9, p <0.001) than other IS and dcSSc (19.4±9.4, p=0.05) despite similar disease duration (median [IQR] months 14.9[19.9] vs 18.4[31.6], p=0.48). In multivariable modeling, no significant association between mRSS and RNA Pol III (p=0.07) or Scl-70 (p=0.09) was found. Radiographic ILD was more prevalent in Fibroproliferative IS compared to other IS (91%, p=0.04) with similar prevalence between lcSSc and dcSSc (67% vs. 76%, p=0.73). Positive Scl-70 antibody was the strongest ILD predictor (p<0.001). Interestingly, all lcSSc/Fibroproliferative patients were demonstrated radiographic ILD.CONCLUSIONS: Classification by IS identifies patients with distinct clinical phenotypes versus traditional cutaneous or autoantibody classification. IS classification identifies subgroups of SSc patients with more radiographic ILD (Fibroproliferative), higher mRSS (Inflammatory) and milder phenotype (Normal-like), and may provide additional clinically useful information to current SSc classification systems. This article is protected by copyright. All rights reserved.
View details for DOI 10.1002/acr.24998
View details for PubMedID 35997480