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 cor onary 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 an d 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 prosp ective studies were included. Available data on risk estimates from 23 stud ies 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 st udies, did not show an association between smoking and CHD. In the 1980s, m ost case control studies found an association but the prospective studies d id 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, the re were one cross-sectional and two case control studies. Conclusions The existing evidence supports that smoking is a cause of CHD i n Chinese, particularly in men. More data in women are needed to quantify t he risk more precisely. The risk estimates probably indicate only the early stage of a growing tobacco epidemic.