Overview
CHARLS is a biennial nationally representative longitudinal survey of the middle-aged and elderly population (45+) in China run by Peking University. A two-province pilot sample was collected in 2008 and followed up in 2012. The national baseline survey started in 2011. The sample was followed in 2013 (wave 2), 2015 (wave 3), and 2018 (wave 4). The survey is harmonized with the HRS family of surveys and collects basic information on all household members, the structure of the family and detailed transfers with family members, individual health status and functioning, health care and insurance, work, retirement and pension, as well as income, consumption and wealth.
Data Collection
The baseline national wave of CHARLS, fielded from May 2011 to March 2012, covered 17,705 individuals in 10,029 households, 450 village-level units and 150 county-level units. It followed stratified random sampling procedures with multi-stage (counties-villages-households) PPS sampling. All counties in mainland China excluding those in Tibet were included in the sampling frame to choose counties. To construct a household sampling frame in village-level units, mapping/listing operations were conducted using CHARLS-GIS software operated on Google-Earth maps. One age-eligible member of the household is randomly selected to be the main respondent. All spouses are included. Refresher samples are identified in the national baseline and will be maintained and drawn into the survey when they become age-eligible in the next five years.
Biomarkers
At each wave anthropometric measures (height, weight, waist circumference, lower right leg length and upper arm length), lung capacity, grip strength, timed sit and stand, timed walk, balance tests, blood pressure and pulse rate were measured.
Blood samples were collected as part of CHARLS. Total and HDL cholesterol were measured using a cardiocheck meter in the 2008 pilot survey and dried blood spots were also collected and analyzed for hs C-reactive protein (CRP) and hemoglobin. Venous blood samples were collected for the national baseline sample (2011 and 2015) and assays now available include complete blood count, CRP, HbA1c, Lipids (total, LDL and HDL cholesterol, Triglycerides), glucose, blood urea nitrogen, creatinine, uric acid and Cystatin C. Blood samples were also collected in 2015.
User Guides
2011 National Baseline Blood Data Users’ Guides
http://charls.pku.edu.cn/pages/data/2011-charls-wave1/en.html
2013 Biomarker Questionnaire (Used for physical measurement)
http://charls.pku.edu.cn/pages/data/2013-charls-wave2/en.html
2015 Biomarker Questionnaire (Used for physical measurement)
http://charls.pku.edu.cn/pages/data/2015-charls-wave4/en.html
2018 National Baseline Blood Data Users’ Guides
http://charls.pku.edu.cn/pages/data/2018-charls-wave4/en.html