Incidence Rate and Prevalence of Systemic Sclerosis and Systemic Sclerosis-Associated Interstitial Lung Disease in Japan: Analysis Using Japanese Claims Databases.

introductionSystemic sclerosis (SSc) is a complex autoimmune disease with increased mortality, and interstitial lung disease (ILD) is a major cause of death. There are no recent epidemiological data on SSc and SSc-associated ILD (SSc-ILD) in Japan and little is known about how patients with these diseases are treated.

methodsThe incidence rate and prevalence of SSc and SSc-ILD in Japan were estimated using the Japanese Medical Data Centre (JMDC) database. The demographic and clinical characteristics of patients and the immunomodulatory medications they received were also assessed using JMDC and the Medical Data Vision (MDV) databases. All analyses were descriptive.

resultsThe overall incidence rates of SSc and SSc-ILD per 100,000 person-years were 6.6 (95% confidence interval [CI] 6.2-7.1) and 1.9 (95% CI 1.6-2.1), respectively, and the overall prevalence per 100,000 persons was 37.0 (95% CI 35.6-38.5) and 13.9 (95% CI 13.0-14.8), respectively. ILD was the most common comorbidity in patients with SSc present in approximately 30% of patients (JMDC, 29.3%; MDV, 30.1%). The immunomodulatory medications prescribed were similar in patients with SSc and SSc-ILD, and each of the medications in this analysis was prescribed in less than 15% of patients.

conclusionWe have demonstrated that estimates of prevalence and incidence rates of SSc and SSc-ILD in Japan are comparable to similar database studies conducted in the USA, using a medical claims database. Only a small proportion of patients were receiving immunomodulatory treatments, suggesting undertreatment in Japan. Incidence Rate and Prevalence of Systemic Sclerosis and Systemic Sclerosis-associated Interstitial Lung Disease in Japan: Analysis Using Japanese Claims Databases-A Video Abstract. (MP4 68892 KB).