Clinical and laboratory features dependent on age at onset in Japanese systemic sclerosis

Objective To clarify those clinical characteristics dependent on patient age at onset of Japanese systemic sclerosis (SSc). Methods: A total of 329 SSc patients treated at Kanazawa University Hospital were enrolled in the study and subsequently categorized into four subgroups depending on age at SSc onset: childhood-onset, young-onset, normal age-onset, and late-onset. The clinical features at the first visit were compared between groups. Factors that correlated with age at onset were also analyzed. Results The childhood-onset subgroup was characterized by a higher male:female ratio, higher anti-topoisomerase I antibody (Ab) and anti-U3 RNP Ab levels, a higher frequency of pitting scars, and a lower frequency of anticentromere Ab and interstitial lung disease (ILD). The young-onset patients had an increased frequency of anti-U1 RNP Ab and anti-U3 RNP Ab, overlap with other connective tissue diseases, digital ulcers, and pitting scars and a reduced frequency of anticentromere Ab. Patients with late-onset SSc showed a shorter disease duration and an increased frequency of anti-RNA polymerase Ab. Multiple regression analysis showed that anti-topoisomerase I Ab, anti-U1 RNP Ab, pitting scars, and long disease duration were associated with onset at a younger age, whereas anticentromere Ab and ILD were associated with onset at an older age. Conclusions The clinical phenotype of SSc in Japanese patients showed a tendency to be dependent on age at onset.