Trends in the incidence of cryptorchidism and hypospadias of registry-based data in Korea: a comparison between industrialized areas of petrochemical estates and a non-industrialized area.

This study aimed to represent the recent trends in the nationwide incidence of cryptorchidism and hypospadias in Korea, and to determine whether there is evidence of spatial heterogeneity in the incidence. The incidence was calculated as the number of newly diagnosed patients (males) during the first 4 years after a live birth in a population, nationally and regionally (a non-industrialized area (Chuncheon) and petrochemical estates (Yeocheon and Ulsan)), between 2000 and 2005. The data (numerator) for new patients were acquired from the National Health Insurance Review Agency, and the data (denominator) for the resident registration population were from the National Statistical Office. Between 2000 and 2005, the national incidence of cryptorchidism and hypospadias had an increased tendency from 5.01 to 17.43 per 10 000 persons and from 1.40 to 3.28 per 10 000 persons, respectively. The incidence of cryptorchidism was significantly higher in Yeocheon (throughout the study period) and in Ulsan (2001, 2002, 2004 and 2005) than the national incidence, whereas the incidence in Chuncheon was significantly lower in 2001 and 2002. It was difficult to compare the rates of hypospadias yearly and regionally because of the small number of cases. In conclusion, the incidence of cryptorchidism has recently increased in Korea. The petrochemical estates, Yeocheon and Ulsan, had a significantly higher incidence of cyptorchidism than the national incidence, which suggests that further study is needed to obtain a more precise estimation of the trends in the incidence of the anomalies and to confirm the association between petrochemicals and the anomalies.