Abstract
PURPOSE: To investigate the epidemiological trends and socioeconomic disparities associated with ankylosing spondylitis (AS) in South Korea over a decade (2010-2021) using National Health Insurance Service (NHIS) claims data. MATERIALS AND METHODS: Employing data from the NHIS database, this study identified 31753 incident AS patients in 2010-2021. We calculated the annual age-standardized prevalence and incidence rates and analyzed crude incidence rates and diagnostic patterns across age groups. Additionally, we compared the mean annual proportions of medical aid recipients between AS patients and the general population, utilizing p for trend analysis to assess the differences between the two groups across increasing age groups. RESULTS: The study period saw a steady increase in age-standardized prevalence (from 34.6 to 91.0 per 100000) and incidence rates (from 4.41 to 8.33 per 100000 person-years), with the most substantial rise of incidence found in younger demographics. Diagnostic trends revealed a shift from internal medicine (IM) to other specialties including orthopedics with increasing patient age groups (p for trend=0.008), indicating old-age diagnosis in non-IM departments. A 1.4-fold higher proportion of medical aid recipients in AS patients (p<0.001) and the widening gap of dependency on medical aid in older age groups (p for trend=0.012) compared to the general population highlight socioeconomic disparities. CONCLUSION: This comprehensive analysis reveals the growing epidemiological burden of AS, especially in younger populations, and the socioeconomic disparities regarding the disease in South Korea. It underscores the need for early diagnosis and effective treatment strategies, paving the way for health interventions and policies aimed at improving patient outcomes and addressing socioeconomic disparities.