Sample data
Samples collected
At baseline a 10 mL non-fasting blood sample was collected from each participant and the time since last meal was recorded. The samples were maintained at 0-4°C and shipped to the local study laboratory for aliquotting into three plasma cryovials and one DNA-containing buffy coat cryovial. They were then stored in a -40°C freezer for three to four months before being couriered on dry ice to the central blood repository in Beijing for storage at -80°C or liquid nitrogen tanks. Two of the frozen plasma aliquots from each participant were couriered to Oxford and stored in liquid nitrogen tanks.
Repeat blood samples and other biological samples (eg urine, saliva and faecal) from participants, were collected during subsequent resurveys.
Various blood tests were conducted at each survey, either on-site using blood spot tests e.g. blood glucose, hepatitis B surface antigen (HBsAg) or at local laboratory using desktop analysers eg lipid-related biomarkers.
Sample assays
Assays of the stored plasma, urine and DNA samples were undertaken using various platforms. These included blood biochemistry, NMR-based metabolomics, MS-based metabolomics, OLINK proteomics, red cell fatty acids, infectious markers, genotyping and whole genome sequencing. Typically, they covered a subset of participants based on the nested case-cohort design for particular diseases. As the cost for many assays continues to fall, we plan to expand the assays to the entire CKB cohort, especially assays related to genetics and multi-omics that are relevant to a wide range of exposures and health outcomes.
