Clinical significance of coexisting antitopoisomerase I and anticentromere antibodies in patients with systemic sclerosis: a EUSTAR group-based study

Objective. To determine the clinical characteristics of simultaneous occurrence of antitopoisomerase (ATA) and anticentromere (ACA) autoantibodies in systemic sclerosis (SSc). Methods. Data of patients (n=4,687) fulfilling the ACR criteria for SSc and followed in the EULAR Scleroderma Trials and Research (EUSTAR) cohort were analysed. Sera from patients with simultaneous ATA and ACA were reanalysed centrally by indirect immunofluorescence, enzyme immunoassay, and immunoblot to confirm antibody status. Results. A total of 29 patients (0.6%) had been documented double-positive for both ATA and ACA in the EUSTAR database. Sera of 14 cases were available for central analysis, of which 8 were confirmed to unequivocally contain both antibodies. The doublepositive patients were on average 52.4 years of age, 87.5% were female, and 62.5% had diffuse cutaneous (dc) SSc. Compared with matched ACA singlepositive disease, cutaneous and visceral complications were more prevalent in double-positive cases, but this prevalence did not differ significantly in comparison to ATA single-positives. Conclusions. Coexistence of ATA and ACA can be found at low prevalence in SSc. The clinical features of doublepositive patients are not clearly dissimilar to those of patients harbouring only ATA. The data do not support a direct involvement of these antibodies in the pathogenesis of established SSc, but may lack statistical power.