Cohort Profile: The Korean Genome and Epidemiology Study (KoGES) Consortium

Abstract

Worldwide globalization and Westernization in social and economic aspects have led to drastic changes in South Korea during the past several decades. These changes include individual health behaviours, which were reflected as increased prevalence of non-communicable chronic diseases (NCDs), such as type 2 diabetes mellitus (T2DM), hypertension, obesity and cardiovascular disease (CVD).1 These NCDs are known to be caused by both environmental risk factors and predisposing genetic factors. Population decline is another issue in South Korea; the recorded fertility rate was ≤ 1.3 births per woman, and ≥ 10% of the population were elderly individuals aged ≥ 65 years according to the Population and Housing Census results of 2005-2010.2,3 We have also been observing an increased influx and efflux of the population due to globalization. In particular, there has been a rising tendency in the marriage-based inflow of South Asian women during the last decade. To attempt to solve public health issues resulting from these population trends and prepare for personalized and preventive health care in the future, the Korean government (National Research Institute of Health (NIH), Centers for Disease Control and Prevention and the Ministry of Health and Welfare, Korea) initiated a large prospective cohort study with government funding, named the Korean genome and epidemiology study (KoGES). The study is a consortium project consisting of six prospective cohort studies that would be categorized into population-based and gene-environment model studies (Figure 1). The aim of the KoGES was to establish a genome epidemiological study platform for the research community with a health database and biobank, to investigate the genetic and environmental aetiology of common complex diseases in Koreans (i.e. T2DM, hypertension, obesity, metabolic syndrome, osteoporosis, CVD,and cancer) and causes of death with long-term follow-up. The ultimate goal of the KoGES was to develop comprehensive and applicable health care guidelines for common complex diseases in Koreans, reduce the burden of chronic diseases and improve the quality of life. Flow diagram of baseline recruitment and follow-up for the Korean genome and epidemiology study (KoGES). *The follow-up survey was conducted in 6 out of 11 counties (baseline number from the six counties = 21 715). **The follow-up recruitment included only immigrant mothers and children. ***The follow-up survey was continued only in Japan due to difficulties in the follow-up of Chinese participants (see the ‘Who is in the cohort consortium and how often have they been followed up?’ section). The population-based cohorts in the KoGES, including the KoGES_Ansan and Ansung study, the KoGES_health examinee (HEXA) study and the KoGES_cardiovascular disease association study (CAVAS), consist of community-dwellers and participants recruited from the national health examinee registry, men and women, aged ≥ 40 years at baseline (Figure 1). The KoGES gene-environment model studies include the KoGES_twin and family study, the KoGES_immigrant study and KoGES_emigrant study (Japan and China). For baseline recruitment, eligible participants were asked to volunteer through on-site invitation, mailed letters, telephone calls, media campaign or community leader-mediated conferences. The responders were invited to visit the survey sites, including ≥ 50 national and international medical schools, hospitals and health institutions (Figure 2), for an interview, a questionnaire administered by trained staff and physical examination. The followed-up participants were invited to complete the surveys by mail and telephone calls periodically. The inclusion criteria for baseline and follow-up recruitment for each cohort are described in Supplementary material (available as Supplementary data at IJE online). Geographical location of the survey sites in the Korean genome and epidemiology study. In Korea (A); Japan (B); China (C). The selected baseline characteristics of participants and disease prevalence are summarized by cohort in Tables 1, 2 and 3, with additional data in Supplementary Table 2 (available as Supplementary data at IJE online). The age-standardized prevalence rates for T2DM, hypertension and obesity among the population-based cohort studies are compared in Table 2. When compared with the age-standardized prevalence rates (≥ 30 years) reported in the Korea National Health and Nutrition Examination Survey (KNHANES III, 2005: hypertension, 28.0%; diabetes, 9.1%⁠; obesity, 34.8%⁠),1 the prevalence of hypertension appeared to be higher in the KoGES population-based studies. A total of 7224 incident cancer cases and 4351 all-cause deaths were identified in the population-based studies between 2001 and 2013 (Table 3). The distribution patterns of leading primary cancer sites by sex were observed to be similar in the constituent studies, which were also comparable with the national cancer statistics, Korea Central Cancer Reg