Resurveying of 1402 participants was completed in Haikou (Hainan Province, RC26) on 16th April. Liuyang (Hunan Province, RC88) and Tongxiang (Zhejiang Province, RC78) started resurvey in mid-March and mid-April respectively. Onsite training was completed in Qingdao Province (RC12) on the 7th May with resurvey starting on the 11th May. The resurvey of the final remaining RC, Gansu (RC58) will be launched on the 15th June.
Approximately 13,500 participants from 5 study areas including Pengzhou (Sichuan Province, RC52), Huixian (Henan Province, RC68), Harbin (Heilongjiang Province, RC16), Suzhou (Jiangsu Province, RC36) and Liuzhou (Guangxi Zhuang Autonomous Region, RC46), had previously been resurveyed in the first phase of the resurvey between August 2013 and January 2014. The overall response rate for the second resurvey currently stands over 75%.
Periodic resurveys of China Kadoorie Biobank are conducted every 4-5 years and cover about 5% (25,000) of the surviving participants. The resurveys allow the relevance of long-term “usual” levels of risk factors to be assessed by allowing appropriate adjustment for “regression dilution” and other sources of variation.