Cohort profile and representativeness of participants in the Diet, Cancer and Health-Next Generations cohort study.

The Diet, Cancer and Health-Next Generations (DCH-NG) study is a large population-based cohort study that was established as a resource for transgenerational research. The cohort is an extension of the Diet, Cancer and Health (DCH) cohort. The aim of this paper was to describe the study design and methods and to investigate the representativeness of participants by comparing participants with non-participants with emphasis on socioeconomic determinants. In 2015-2019, children (G1), their spouses (G1P) and grandchildren (G2) of DCH cohort members were invited to participate. Participants completed questionnaires, a physical examination and collection of biological material. Information on general and sociodemographic variables was obtained by linkage to administrative registries in Denmark. The cohort includes 39,554 adult participants with complete data collection. Participants are represented in different family structures including 2- and 3-generation relationships, offspring-parents trios and siblings. The odds ratio for participation was highest among G1, females, middle-aged and married individuals and individuals with the highest education, highest income, occupations requiring high-level skills and residency near a study centre. The different family structures allow a range of studies with cohort and transgenerational designs. The pattern of more likelihood of participation in higher socioeconomic groups was similar to the pattern of participation in the DCH cohort and the general patterns in population-based studies. Accordingly, the study population has some limitations as to being representative of the general population. Yet, the DCH-NG cohort will provide valuable insight on the association between risk factor-disease relationships and the role of heredity on these associations.