Investigation of prognostic factors for skin sclerosis and lung function in Japanese patients with early systemic sclerosis: a multicentre prospective observational study

Objective. To clarify the clinical course of SSc in Japanese patients with early-onset disease. It is well known that ethnic variations exist in the clinical features and severity of SSc. However, neither the clinical course nor prognostic factors have been thoroughly investigated in the Japanese population. Methods. Ninety-three Japanese patients of early-onset SSc (disease duration: <3 years) with diffuse skin sclerosis and/or interstitial lung disease were registered in a multi-centre observational study. All patients had a physical examination with laboratory tests at their first visit and at each of the three subsequent years. Factors that could predict the severity of skin sclerosis and lung involvement were examined statistically by multiple regression analysis. Results. Two patients died from SSc-related myocardial involvement and four patients died from other complications during the 3-year study. Among various clinical data assessed, the initial modified Rodnan total skin thickness score (MRSS) and maximal oral aperture were associated positively and negatively with MRSS at Year 3, respectively. Additionally, initial ESR tended to be associated with final MRSS. Pulmonary vital capacity (VC) in the third year was significantly associated with initial %VC. Furthermore, patients with anti-topo I antibody tended to show reduced %VC at Year 3. Conclusions. Several possible prognostic factors for skin sclerosis and lung function were detected in Japanese patients with early SSc. Further longitudinal studies of larger populations will be needed to confirm these findings.