Background: The prevalence of coronary artery disease in southern China is approximately one fifth that in "westernized" countries, even though approximately 70% of Chinese men smoke cigarettes and Chinese women have substantial passive exposure to cigarette smoke.
Objectives: Endothelial dysfunction is an early event in atherosclerosis and occurs in young white active and passive smokers; we compared endothelial physiology in healthy young Chinese and white smokers and nonsmokers.
Patients: 144 healthy adults who were 16 to 45 years of age: 72 Chinese persons in a village in southern China and 72 white persons in Australia and England who were matched for exposure to cigarette smoke. Each ethnic group comprised 36 controls (lifelong nonsmokers with no regular exposure to cigarette smoke; 16 men and 20 women) and 36 active or passive smokers (15 men and 21 women).
Measurements: Arterial endothelial function was tested with high-resolution external vascular ultrasonography, and brachial artery diameter was measured at rest, after flow increase (which causes endothelium-dependent dilatation), and after administration of sublingual nitroglycerin (an endothelium-independent dilator).
Results: Endothelium-dependent dilatation was similar in Chinese (7.9%) and white (8.4%) nonsmokers (P > 0.2). Among white persons, endothelium-dependent dilatation was lower in active or passive smokers (3.9%) than in nonsmokers (8.4%) (P < 0.001). Among Chinese persons, dilatation was not significantly lower in active or passive smokers (7.3%) than in nonsmokers (7.9%) (P > 0.2). Dilatation was higher in Chinese active or passive smokers (7.3%) than in white active or passive smokers (3.9%) (P < 0.001). Dilatation responses to nitroglycerin were similar in all groups (P = 0.17).
Conclusion: Young Chinese adults have less evidence of arterial endothelial dysfunction than young white adults with similar direct or indirect exposure to cigarette smoke.