Geographic study of mortality, biochemistry,
diet and lifestyle in rural China
(Surveys in 1983, 1989 and 1993 of biochemistry, diet and lifestyle in 69 nationally representative rural counties, and correlations with cause-specific death rates in those counties in 1973-75 and 1986-88)
Principal investigators: Chen Junshi (Chinese Academy of Preventive Medicine), Liu Boqi (Chinese Academy of Medical Sciences), Pan Wenharn (Academia Sinica), Colin Campbell (Cornell University) and Richard Peto (University of Oxford)
Objectives: To describe the wide variation across 69 rural Chinese counties in diet, lifestyle, blood and urine biochemistry and mortality rates, characterising each county by the average of the characteristics of those living there (so the chief comparisons are between counties, not between individuals).
Design: (i) Surveys in 1983 and 1989 of individuals and households in two randomly chosen villages in each of 69 rural Chinese counties; and (ii) determination of cause-specific mortality rates in the whole of each of those counties for 1973-75 and 1986-88.
Techniques: (i) 8000 adults (60 per village x 2 villages x 69 counties) were interviewed at length and provided blood and urine samples, and a 3-day weighed dietary survey was completed for 4000 households (30 per village x 2 x 69). The whole survey was performed twice, in 1983  and in 1989, allowing reproducibility to be assessed, and in 13 of the counties it was repeated again 4 years later. (ii) The 1973-75 county-specific mortality rates were obtained from another study [2,3], and the 1986-88 mortality rates from a review of 300,000 individual death records . Several hundred descriptive variables have been constructed and the mean values of them for each county have been tabulated, correlated and plotted.
Measurements: (i) Six interviewer-administered questionnaires recorded individual characteristics (social factors, diet, health, smoking, alcohol consumption, other aspects of lifestyle, height, weight, blood pressure, lung function, etc), household characteristics (family structure, physical characteristics of the house, income, amenities, 3-day food consumption, cooking and heating fuel, etc), and village and county characteristics (location, climate, economic level, etc). Special surveys were done in each county of maternal education, infant feeding patterns, and height for age in schoolchildren. Laboratory measurements were made of various blood lipids, proteins, trace elements, antibodies (and, for hepatitis B, the surface antigen), cotinine and fatty acid profile (from red blood cell membranes). Among men, urinary cotinine, electrolytes and aflatoxin metabolites were also measured, and proline load tests were done to assess ascorbate-inhibitable gastric nitrosation rates. (ii) Age-standardised cause-specific mortality rates (1973-75, 1986-88) were calculated for each county.
Implications: The chief purpose is to describe the wide range of
differences between different counties in lifestyles and disease-specific
mortality rates in rural China, rather than to analyse differences between
counties in search of direct evidence of causes. A few of the
"ecological" (i.e. geographic) correlations of particular factors
with particular diseases do yield good evidence of causality, but the real
importance of this study is purely descriptive: better appreciation of the
extraordinarily wide range of lifestyles and of disease rates across different
Chinese counties will lead to more specific studies.