The German National Cohort: aims, study design and organization

The German National Cohort (GNC) is a joint interdisciplinary endeavour of scientists from the Helm- holtz and the Leibniz Association, universities, and other research institutes. Its aim is to investigate the causes for the development of major chronic diseases, i.e. cardio- vascular diseases, cancer, diabetes, neurodegenerative/- psychiatric diseases, musculoskeletal diseases, respiratory and infectious diseases, and their pre-clinical stages or functional health impairments. Across Germany, a random sample of the general population will be drawn by 18 regional study centres, including a total of 100,000 women and 100,000 men aged 20-69 years. The baseline assess- ments include an extensive interview and self-completion questionnaires, a wide range of medical examinations and the collection of various biomaterials. In a random sub- group of 20 % of the participants (n = 40,000) an inten- sified examination (''Level 2'') programme will be performed. In addition, in five of the 18 study centres a total of 30,000 study participants will take part in a mag- netic resonance imaging examination programme, and all of these participants will also be offered the intensified Level 2 examinations. After 4-5 years, all participants will be invited for a re-assessment. Information about chronic disease endpoints will be collected through a combination of active follow-up (including questionnaires every 2-3 years) and record linkages. The GNC is planned for an overall duration of 25-30 years. It will provide a major, central resource for population-based epidemiology in Germany, and will help to identify new and tailored strategies for early detection, prediction, and primary pre- vention of major diseases.