Arthritis in patients with very early systemic sclerosis: a comprehensive clinical and prognostic analysis

OBJECTIVE Arthritis is associated with a worse prognosis in established systemic sclerosis (SSc). However, knowledge about its relevance in very early SSc (veSSc) is scarce. We aimed to assess the prevalence and phenotype of arthritis, as well as its prognostic impact, in patients with veSSc. METHODS We analysed patients with veSSc, defined as presence of Raynaud's phenomenon and/or at least one of: puffy fingers, antinuclear antibodies (ANA), abnormal capillaroscopy, not fulfilling the ACR/EULAR classification criteria for SSc at baseline. We investigated associations between arthritis and clinical parameters, followed by a longitudinal analysis to investigate arthritis as a potential predictor of progression towards established SSc. RESULTS We included 159 patients, of whom 108 had at least one follow-up visit. SSc-related arthritis occurred in 22/159 (13.8%) patients at baseline. Arthritis was mostly seronegative, symmetrical, oligo- or polyarticular, non-erosive, and rarely associated with elevation of inflammatory markers. More than half of the patients needed treatment with DMARDs. Anti-centromere antibodies were negatively associated with arthritis (OR: 0.707, 95% confidence interval 0.513-0.973, p = 0.033). Overall, 43/108 (39.8%) patients with follow-up progressed to established SSc during the observation time. Arthritis was not a significant predictor for progression to established SSc in a multivariable Cox regression. CONCLUSION In this first comprehensive analysis, we found a similar prevalence of arthritis in veSSc as seen in established SSc. Moreover, the use of DMARDs indirectly suggests a relevant disease burden.