BACKGROUND: Systemic sclerosis (SSc) is a complex disease whose diagnosis is based on clinical manifestations, serological testing for autoantibodies, and nailfold capillaroscopy. Although some proteins have been proposed as biomarkers, the diagnosis of SSc remains a challenge for clinicians. The soluble oncostatin M receptor (sOSMR) is a potential biomarker for the diagnosis of SSc, as it appears to act as an antagonist of oncostatin M (OSM)-mediated signaling, which is involved in biological and inflammatory processes, including tissue injury and fibrosis. Therefore, this study aimed to evaluate the diagnostic performance of sOSMR in systemic sclerosis. METHODOLOGY: Serum samples were collected from 105 patients with SSc, 50 with rheumatoid arthritis (RA), 64 with systemic lupus erythematosus (SLE), and 130 healthy controls (HC). The sOSMR levels were measured using an ELISA kit, and a receiver operating characteristic (ROC) curve was used to analyze the biomarker's potential for diagnosing SSc. RESULTS: sOSMR levels are significantly elevated in the serum of patients with SSc when compared to patients with RA and SLE, as well as healthy controls (p <
0.0001 for all comparisons). The area under the curve (AUC) of ROC curve analysis revealed the ability of sOSMR serum levels to distinguish patients with SSc from those with RA (0.901 [95 % CI 0.842-0.943]
p <
0.0001), with a sensitivity of 89.52 % and specificity of 78.00 %, and from patients with SLE (0.897 [95 % CI 0.841-0.938]
p <
0.0001), with a sensitivity of 81.90 % and specificity of 89.06 %, as well as from healthy controls (0.876 [95 % CI 0.827 - 0.916]
p <
0.0001), with a sensitivity of 82.86 % and specificity of 81.54 %. When comparing patients with SSc to patients with other diseases (RA and SLE combined), an AUC of 0.898 ([95 % CI 0.851-0.935]
p <
0.0001) was found, with a sensitivity of 82.86 % and specificity of 85.09 %. CONCLUSION: Serum sOSMR levels are elevated in patients with SSc and have shown a good ability to distinguish between SSc patients, patients with other autoimmune rheumatologic diseases (RA and SLE), and healthy controls. Thus, sOSMR is a promising marker for diagnosing SSc.