The Health Examinees (HEXA) study: rationale, study design and baseline characteristics.
BACKGROUND
Korea has experienced rapid economic development in a very short period of time. A mixture of traditional and modern risk factors coexists and the rapid change in non-genetic factors interacts with genetic constituents. With consideration of these unique aspects of Korean society, a large-scale genomic cohort study-the Health Examinees (HEXA) Study-has been conducted to investigate epidemiologic characteristics, genomic features, and gene-environment interactions of major chronic diseases including cancer in the Korean population.


METHODS
Following a standardized study protocol, the subjects were prospectively recruited from 38 health examination centers and training hospitals throughout the country. An interview- based questionnaire survey was conducted to collect information on socio-demographic characteristics, medical history, medication usage, family history, lifestyle factors, diet, physical activity, and reproductive factors for women. Various biological specimens (i.e., plasma, serum, buffy coat, blood cells, genomic DNA, and urine) were collected for biorepository according to the standardized protocol. Skilled medical staff also performed physical examinations.


RESULTS
Between 2004 and 2013, a total of 167,169 subjects aged 40-69 years were recruited for the HEXA study. Participants are being followed up utilizing active and passive methods. The first wave of active follow-up began in 2012 and it will be continued until 2015. The principal purpose of passive follow-up is based on data linkages with the National Death Certificate, the National Cancer Registry, and the National Health Insurance Claim data.


CONCLUSIONS
The HEXA study will render an opportunity to investigate biomarkers of early health index and the chronological changes associated with chronic diseases.
Details of the study group members are provided in the Acknowledgments. E-mail : dhkang@snu.ac.kr.
Health Examinees Study Group
D000328:Adult; D000368:Aged; D004032:Diet; D015340:Epidemiologic Research Design; D005260:Female; D005500:Follow-Up Studies; D059647:Gene-Environment Interaction; D023281:Genomics; D006801:Humans; D015994:Incidence; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics; D011446:Prospective Studies; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D011795:Surveys and Questionnaires