Periodic resurveys of are conducted every 4-5 years and cover about 5% (25,000) of the surviving participants. The resurveys assess long-term usual level of risk factors in order to adjust for ‘regression dilution’ and other sources of variation.
The second resurvey was conducted between August 2013 and September 2014, two or three RCs at a time. This allowed the equipments to be shared and some freedom for the RCs to decide when to start the resurvey. The survey team recruited in each RC received four-days onsite training about standard operating procedures by the CKB second resurvey training team including colleagues from ICC (International Collaborating Centre, Oxford University), NCC (National Collaborating Center, Chinese Academy of Medical Science) and sonographers (ultrasound experts) from Peking Union Medical College Hospital. During the second resurvey, participants were interviewed using an electronic questionnaire; were measured for a range of physical parameters; and provided 10 ml blood sample plus 10 ml urine sample for onsite spot tests (blood glucose, blood lipids and urine routine test) and long-term storage. The questionnaire used during the second resurvey was the updated version of the baseline questionnaire, asking all information collected during the baseline survey plus several dozens of new variables such as ethnicity, coffee consumption, amount of food group consumption, consumption of salt, cooking oil and soft drinks, COPD treatment etc. In addition to the physical measurements taken during the baseline survey, heel bone density, 12 lead ECG, pulse wave velocity, handgrip strength, ankle-brachial index, and carotid intima media thickness and plaques measurements were also performed to collect more detailed information on risk factors of chronic diseases, in particular cardiovascular disease.
Data from the second survey is now being reviewed and will be added to the snapshot database for CKB researchers to access by the end of 2014.