The Chinese Longitudinal Healthy Longevity Survey (CLHLS), supported by NIA and Chinese resources, conducted face-to-face interviews in 1998, 2000, 2002, 2005, 2008-2009, 2011-12, 2014, respectively, using internationally compatible questionnaires. The CLHLS project has the largest sample of centenarians in the world (plus compatible groups of nonagenarians, octogenarians, and young-old aged 65-79). The goal of the survey is to determine which factors, out of a large set of social, behavioral, and environmental risk factors, play an important role in healthy longevity. The large population size, the focus on healthy longevity (rather than on a specific disease or disorder), the simultaneous consideration of various risk factors, and the use of analytical strategies based on demographic concepts make this an innovative demographic data collection and research project.
The CLHLS project focuses on the oldest-old aged 80 and older from 22 provinces in mainland China. From 2002 on, the CLHLS includes those young elders aged 65-79 for comparison. The baseline survey was conducted in 1998, with follow-up surveys with replacement for deceased elders, were conducted in 2000, 2002, 2005 and 2008-2009 in a randomly selected half of the total number of counties and cities in the 22 provinces. The survey areas covered 1.1 billion people (85% of the total population in China). The baseline survey included approximately 9,000 individuals, and follow-up surveys included approximately 11,200 respondents in 2000, 20,200 in 2002, 18,500 in 2005, 19,900 in 2008-09, 9,679 in 2011-2012, and 7,107 in 2014. Among approximately 80,000 interviews conducted in the first five waves, 14,376 were with centenarians, 18,938 with nonagenarians, 20,823 with octogenarians, 14,285 with younger elders aged 65-79, and 10,962 with middle-age adults aged 35-64. Data on mortality and health status before dying for the 17,649 elders aged 65-110 who died between waves were collected in interviews with a close family member of the deceased.
Biomarkers available in the CLHLS include weight, height, blood pressure, heart rhythm and rate, peak lung flow (1998 only), lower and upper extremities performance. In addition, dry blood spot samples were collected from 4,116 oldest-old aged 80 and older in the CLHLS 1998 baseline survey. About 14,000 DNA samples were collected (including 12,032 individuals with saliva samples only, 1,826 individuals with both whole blood and saliva samples and 119 individuals with whole blood samples only) in the CLHLS 2008-2009 wave. In total, we have DNA samples from 18,093 individuals, including 3,312 centenarians, 4,375 nonagenarians, 4,658 octogenarians, 3,250 younger elderly aged 65-79, and 2,521 controls aged 40-64. As part of CLHLS data/DNA sample collection, interviews and a health exam with blood/urine collection by local medical personnel were carried out in Feb.-June 2009 in the seven “Chinese Longevity Areas (CLA)” professionally evaluated and formally designated by the Chinese Society of Gerontology. These 2009 samples consist of 2,029 participants and among them 1,939 (95.1%) provided their venous blood for biomarkers testing including 369 centenarians, 354 nonagenarians, 336 octogenarians, 419 young-old aged 60-79 and 461 adults aged 40-59. The CLHLS biomarker data were released in 2008-2009 (5th), 2012 (6th), and 2014(7th).