Significant Decline in the Incidence of Behçet's Disease in South Korea: A Nationwide Population-Based Study (2004-2017).

Objective: Long-term population-based data on change in the incidence of Behçet's disease (BD) are scarce, although a possible decline has been reported. The present study was undertaken to investigate the incidence, survival, and mortality of BD patients from 2004 to 2017 in the Republic of Korea.

Methods: We analyzed a registry of rare intractable diseases and a claims database from the Health Insurance and Review Agency with information on BD patients between 2004 and 2017 using uniform diagnostic criteria. The study period was divided into 3 time periods: 2004-2006, 2007-2010, and 2011-2017.

Results: The annual incidence of BD decreased from 8.15 per 100,000 in 2004 to 1.51 in 2017, an 81.5% decrease. The annual percentage change was 6.32% for female patients and 6.15% for male patients. The decrease in BD incidence was greater for women and middle-aged people. The 3-year survival rate of BD patients during the 2011-2017 period was lower than that of BD patients in 2004-2006 and 2007-2010, although there was no statistical difference. The standardized mortality rates increased significantly in the 2011-2017 period compared to the first 2 periods.

Conclusion: BD incidence decreased from 2004 to 2017 in the Republic of Korea. This decline in incidence might be attributable to changes in environmental factors, including a reduction in the burden of infectious diseases in the past decades and improvement in oral health during childhood. The unprecedented decline in the incidence of BD in the Republic of Korea without major changes in genetic background suggests that environmental factors are very important to the development of BD.