Oral Corticosteroid Prescription Trends in South Korea: A 10-Year Nationwide Population-Based Study Using the NHIS-NSC

Objectives To investigate long-term trends in oral corticosteroid (OCS) prescribing among the adult population in South Korea and to evaluate variations in prescribing patterns across diagnoses, healthcare institution types, and clinical specialties using a comprehensive national claims database. Methods This population-based retrospective cohort study was conducted using the National Health Insurance Service–National Sample Cohort (NHIS-NSC), a nationally representative administrative claims database comprising approximately 1 million individuals in South Korea, sampled in 2002 and followed longitudinally. Adults aged 20 years or older who received at least one prescription for oral corticosteroids (OCS) between January 1, 2003, and December 31, 2012, were included in the analysis. Individuals with incomplete demographic or prescription data or those who received only inhaled or topical corticosteroids during the study period were excluded. The primary outcome was the annual prevalence of OCS users, defined as individuals with at least one OCS prescription per year. Users were further classified by frequency into short-term (1–2 prescriptions/year), mid-term (3–5 prescriptions/year), and long-term (≥ 6 prescriptions/year) groups. Secondary outcomes included the most frequently associated diagnostic categories and subcategories based on ICD-10 codes, and the distribution of OCS prescriptions by healthcare institution type (clinics, hospitals, general hospitals) and clinical specialty. Particular attention was given to prescribing trends in dermatologic (L20–L30), urticarial (L50), and respiratory (J00–J99) conditions, given their high contribution to overall corticosteroid use and relevance to guideline-based prescribing. Results Between 2003 and 2012, the proportion of OCS users increased from 20.8–29.2%, representing a 40% relative rise. While the proportion of short-term users declined, mid- and long-term use increased steadily. Dermatologic and respiratory conditions were the leading causes of OCS prescriptions, particularly allergic contact dermatitis (L23) and urticaria (L50), which showed long-term use in 14.5% and 5.9% of users, respectively. Prescribing rates for these conditions were disproportionately high in clinic settings compared to hospitals and general hospitals. Cross-national comparisons revealed that South Korea has higher rates of long-term OCS use and more frequent use in conditions where systemic corticosteroids are not routinely recommended, as compared to countries such as France, the United Kingdom, Denmark, and Iceland. Conclusions OCS prescribing in South Korea has increased significantly over the past decade, particularly in primary care for dermatologic and allergic conditions that are not strongly supported by current clinical guidelines. The high prevalence of long-term use in mild-to-moderate conditions and in clinic-based care highlights the need for more rigorous prescribing protocols, expanded education on adverse effects, and broader implementation of alternative treatment strategies. These findings underscore the importance of national-level interventions to promote evidence-based corticosteroid use and mitigate the risk of unnecessary exposure in the general population.