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A review on studies of smoking and coronary heart disease in China and Hong Kong.

PURPOSE
To document and review all the published reports on smoking and coronary heart disease (CHD) in China and Hong Kong, and to estimate the risks of CHD due to smoking.


DATA SOURCES
Papers cited in Medline, Chinese Biomedical Literature Disc and Chinese Medical Current Contents, references in review papers, conference papers and abstracts.


STUDY SELECTION
All published reports which had findings on smoking and CHD were included.


DATA EXTRACTION
Reports on 13 cross-sectional, 16 case-control and 13 prospective studies were included. Available data on risk estimates from 23 studies were extracted and pooled odds ratios (OR) and relative risks (RR) were calculated using Mantel-Haenszel's methods.


RESULTS
In China in 1970s, most results, which were from cross-sectional studies, did not show an association between smoking and CHD. In the 1980s, most case control studies found an association but the prospective studies did not. In the 1990s, there was stronger evidence from prospective studies mainly in men. The relative risk was about 1.90 in men and about 2.50-3.50 in women although the 95% confidence interval for the latter was wide. Dose response relationships were observed in 12 studies. In Hong Kong, there were one cross-sectional and two case control studies.


CONCLUSIONS
The existing evidence supports that smoking is a cause of CHD in Chinese, particularly in men. More data in women are needed to quantify the risk more precisely. The risk estimates probably indicate only the early stage of a growing tobacco epidemic.