Cohort profile: National Investigation of Birth Cohort in Korea study 2008 (NICKs-2008).

Background An adequate large-scale pediatric cohort based on nationwide administrative data is lacking in Korea. Purpose This study established the National Investigation of Birth Cohort in Korea study 2008 (NICKs-2008) based on data from a nationwide population-based health screening program and data on healthcare utilization for children. Methods The NICKs-2008 study consisted of the Korean National Health Insurance System (NHIS) and the National Health Screening Program for Infants and Children (NHSPIC) databases comprising children born in 2008 (n = 469,248) and 2009 (n = 448,459) in the Republic of Korea. The NHIS database contains data on age, sex, residential area, income, healthcare utilization (International Classification of Diseases-10 codes, procedure codes, and drug classification codes), and healthcare providers. The NHSPIC consists of seven screening rounds. These screening sessions comprised physical examination, developmental screening (rounds 2-7), a general health questionnaire, and age-specific anticipatory guidance. Results During the 10-year follow-up, 2,718 children (0.3%) died, including more boys than girls (hazard ratio = 1.145, p < 0.001). A total of 848,048 children participated in at least one of the seven rounds of the NHSPIC, while 96,046 participated in all seven screening programs. A total of 823 infants (0.1%) weighed less than 1000 g, 3177 (0.4%) weighed 1000-1499 g, 37,166 (4.4%) weighed 1500-2499 g, 773,081 (91.4%) weighed 2500-4000 g, and 32,016 (5.1%) weighed over 4000 g. There were 23,404 (5.5%) premature babies in 2008 compared to 23,368 (5.6%) in 2009. The developmental screening test indicated appropriate development in 95-98% of children, follow-up requirements for 1-4% of children, and recommendations for further evaluation for 1% of children. Conclusion The NICKs-2008, which integrates data from the NHIS and NHSPIC databases, can be used to analyze disease onset prior to hospitalization based on information such as lifestyle, eating habits, and risk factors.