Epidemiology of Polymyalgia Rheumatica in Korea

Objective. Polymyalgia rheumatica is a chronic inflammatory disease that affects people older than 50 years of age. The diagnosis is made based on clinical features, and the current standard of treatment is low-dose glucocorticoids. PMR is more commonly reported in Caucasians and females. However, epidemiological studies of PMR in Asian countries are scarce. We aimed to estimate the epidemiology of PMR in Korea. Methods. This study was conducted by analyzing the Health Insurance Review and Assessment databases. We verified all claims between 2007 and 2012. Cases were included when PMR ICD-10 code (M 35.3) was recorded more than twice, and glucocorticoids were prescribed for ≥30 days. Results. We identified 1,463 newly diagnosed cases of PMR during the 5 years. Among them, 992 (67.8%) were female, and the mean age at diagnosis was 66.9 years old. The annual incidence rate was 2.06 per 100,000 individuals aged over 50 years. The prevalence rate was 8.21 per 100,000 individuals in 2012. Incidence and prevalence appeared to increase with age. Prednisolone was the most commonly prescribed glucocorticoid. In half of the patients, the daily starting dose was 6∼15 mg as prednisolone equivalents. Conclusion. This is the first study to investigate the epidemiology of PMR in Korea. The incidence and prevalence appeared to be considerably lower than those in Western populations. Both genetic and environmental factors might influence disease occurrence. In addition, the actual incidence may have been underestimated due to lack of awareness of PMR in clinical practice.