Background: Although smoking is a major risk factor for cardiovascular disease, it has been suggested that Asians may be less susceptible to the adverse effects of smoking than Caucasians. This may have contributed to the high prevalence of smoking, and the low quitting rates, in Asian men. Worldwide, smoking rates are increasing for women, amongst whom cardiovascular awareness is relatively poor.
Methods: An individual participant data analysis of 40 cohort studies was carried out, involving 463 674 Asians (33% female) and 98 664 Australasians (45% female). Cox proportional hazard models, stratified by study and sex where appropriate, were employed.
Results: The HR [95% confidence interval (CI)], comparing current smokers with non-smokers, for coronary heart disease (CHD) was 1.60 (1.49-1.72); haemorrhagic stroke 1.19 (1.06-1.33); ischaemic stroke 1.38 (1.24-1.54). There was a clear dose-response relationship between the number of cigarettes smoked per day and both CHD and stroke, with no significant difference (P >/= 0.20) between populations from Asia and Australia/New Zealand. Although there was no sex difference for stroke in the effect of amount smoked (P = 0.16), for CHD, women tended to have higher hazard ratios than men (P = 0.011). Quitting gave a clear benefit, which was not significantly different between the sexes or regions (P > 0.63). The HR (CI) for ex-smokers compared with current smokers was 0.71 (0.64-0.78) for CHD and 0.84 (0.76-0.92) for stroke.
Conclusions: Unless urgent public health measures are put into place, the impact of the smoking epidemic in Asia, and among women, will be enormous. Tobacco control policies that specifically target these populations are essential.