Clinical subsets, skin thickness progression rate, and serum antibody levels in systemic sclerosis patients with anti–topoisomerase I antibody

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Abstract
Objective To describe the clinical and laboratory features and natural history of the disease in systemic sclerosis (SSc; scleroderma) patients with anti–topoisomerase I (anti–topo I) antibody who have different skin thickness progression rates (STPRs). Methods SSc patients (n = 212) who were anti–topo I antibody positive were divided into 5 subgroups based on STPRs. Skin thickness was measured using the modified Rodnan skin thickness score (MRSS). Anti–topo I IgG antibody levels were determined. Results Sixty patients who were anti–topo I antibody positive had diffuse cutaneous SSc (dcSSc) with rapid progression, 82 had dcSSC with intermediate progression, and 29 had dcSSc with slow progression, 14 had limited cutaneous SSc (lcSSc) that became dcSSc, and 27 had lcSSc that did not change throughout. Patients beginning with lcSSc were younger at disease onset and had longer disease duration when diagnosed as having SSc. Interstitial lung disease was common and was equally distributed across the subgroups. Renal crisis occurred most often in patients with rapid progression (22%) and was absent in lcSSc patients. Cardiac involvement was most frequent in the dcSSc subgroups. Both kidney and heart disease occurred most often within 3 years after the onset of skin thickening. The 10‐year cumulative survival rate was <40% for patients with rapid and intermediate progression. Renal and cardiac causes of death were disproportionately frequent in these 2 subgroups. Anti–topo I antibody levels correlated with the STPR and the MRSS. Conclusion Anti–topo I antibody–positive patients with SSc with a rapid STPR have reduced survival rates, primarily due to early and often fatal renal and cardiac involvement. Anti–topo I antibody levels parallel the MRSS at the first visit and the STPR. This information is important for managing physicians and researchers planning clinical trials involving patients with early dcSSc.