Incidence of congenital hypothyroidism in China: data from the national newborn screening program, 2013-2015

Background: Congenital hypothyroidism (CH) is one of the most frequent, preventable causes of mental retardation. Little has been reported on the epidemiological characteristics of CH in China. We aimed to estimate the incidence of CH in China and investigate its geographical variation. Methods: We analyzed data from the nationwide newborn screening program for CH between 2013 and 2015. Poisson regression was used to generate the odds ratios (ORs) and 95% confidence intervals (CIs) between the rates of CH and selected demographic characteristics and assess the potential association between CH incidence and geographical locations. Results: A total of 18,666 patients with CH were identified from 45.2 million newborns, yielding an overall incidence rate of 4.13 per 10,000 live births. Compared with those in the remote area, regardless of infant sex, a higher incidence risk for CH was present in newborns in coastal areas and inland areas (females: OR = 2.00, 95% CI: 1.86-2.16 and OR = 1.74, 95% CI: 1.61-1.87, respectively; males: OR = 1.70, 95% CI: 1.59-1.83 and OR = 1.52, 95% CI: 1.42-1.63, respectively). Additionally, the highest risk of CH for thyroid-stimulating hormone (TSH) screening values <40 mU/ L was observed among neonates in the coastal areas, while TSH screening values of 70-100 mU/ L were observed among those in the inland areas. Conclusions: The overall incidence of CH is high in China. The significant geographical variations of CH incidence are presented in this study.