Trends in long-term glucocorticoid use and risk of 5-year mortality: a historical cohort study in South Korea

Purpose This study investigated trends in chronic glucocorticoid (GC) use in South Korea, and determined the association between chronic GC use and 5-year all-cause mortality. Methods A sample cohort was extracted from the South Korean National Health Insurance database. Patients prescribed a continuous dose of GC for >= 30 days were defined as chronic GC users. Time-dependent Cox regression was used for statistical analysis, and chronic GC exposure was considered a time-varying variable. Results The prevalence of chronic GC use gradually increased from 0.16% in 2002 to 0.54% in 2015. In the 2010 cohort (n = 822,097), chronic GC users had a significantly 1.41-fold higher 5-year all-cause mortality compared with controls [hazard ratio: 1.41, 95% confidence interval (CI): 1.28-1.55,P < 0.001]. On sensitivity analysis, chronic high-dose GC users showed 1.52-fold (HR: 1.52, 95% CI: 1.32-1.76;P < 0.001) and low-dose GC users showed 1.34-fold (HR: 1.34, 95% CI: 1.18-1.51;P < 0.001) higher 5-year all-cause mortality, compared with controls; the disease-specific 5-year mortality risk in chronic GC users was highest due to musculoskeletal disease (HR: 9.50), followed by infectious and parasitic diseases (HR: 2.43), and respiratory disease (HR: 2.18). Conclusions Numbers of chronic GC users gradually increased during 2002-2015; chronic GC use increased risks of 5-year all-cause mortality in the general adult South Korean population. This association was more evident among high-dose GC users (>5 mg/day of prednisolone). The risk of disease-specific mortality among chronic GC users was increased in those with musculoskeletal, infectious and parasitic, and respiratory diseases.