Smoking-associated mortality in a cohort of Singaporeans observed for 20 years

Smoking is well established as a main cause of preventable mortality throughout the world, but little data are available on Asian populations and none on Singapore. This study is the first to provide data specific to Singapore on the increased mortality among smokers, and is one of the few such studies on Asians. In 1974, smoking history data were taken from a random sample of 3579 adults living in Singapore. Of these, 3361 (1522 men and 1839 women) were eligible for follow-up and vital status was determined as at 31 December 1993. Cox regression analysis was used to estimate the relative risks of variety of causes of death for smokers compared to non-smokers, adjusted for age and ethnicity. Smoking was categorized as ever or never and also as none, light or heavy. As at 31 December 1993, 330 (21.7%) of the men and 249 (13.5%) of the women had died. Relative risk values were clearly elevated for male and female smokers for all-cause mortality (1.42 and 1.52, respectively), lung cancer (13.2, 6.37) and death due to chronic obstructive pulmonary disease (COPD) (4.71, 8.50). Relative risk values for death from cancer of the larynx or oesophagus, ischaemic heart disease and cerebrovascular disease were elevated but not significantly different from 1.0. A trend of increasing risk with increasing smoking intensity was seen for all-cause mortality among men and for lung cancer and COPD mortality, among both sexes. Ethnicity was associated with ischaemic heart disease mortality among men, with elevated risks in both the Indians (2.55) and the Malays (1.66) relative to the Chinese. These results should serve to strengthen the anti-smoking campaigns in Singapore.