Mortality attributable to cigarette smoking in a cohort study in Japan
BACKGROUND Assessment of the impact of cigarette smoking on mortality helps to indicate the importance of tobacco control in a given country. OBJECTIVES To examine the relative risk of dying from various diseases for cigarette smoking and to estimate annual mortality attributable to cigarette smoking in Taiwan. DESIGN Prospective cohort study. SUBJECTS AND SETTING A cohort of 14,397 male and female residents aged 40 years or older recruited from 12 townships and precincts in Taiwan from 1982 to 1986. Information on cigarette smoking was collected from each subject at local health centres through a standardised personal interview based on a structured questionnaire. They were followed up regularly to determine their vital status until 1994. MAIN OUTCOME MEASURES Cox's proportional hazards regression models were used to derive relative risks of cause-specific mortality for current cigarette smokers compared with never-smokers, and to examine dose-response relationships between mortality from various causes and several measures of cigarette smoking (daily consumption, duration, age of initiation, and cumulative smoking in pack-years). RESULTS A total of 2552 persons died during the study period. Among men, cigarette smoking was significantly associated with an increased risk of dying from all causes combined (relative risk (RR) = 1.3); cancer of all sites combined (RR = 1.5); cancers of the stomach (RR = 1.9), liver (RR = 2.2), and lung (RR = 3.7); ischaemic heart disease (RR = 1.8); other heart diseases (RR = 1.4); and chronic obstructive pulmonary disease (RR = 1.9). Among women, cigarette smoking was significantly associated with an increased risk of dying from all causes combined (RR = 1.8), cancer of the lung (RR = 3.6), and peptic ulcer (RR = 17.8). The estimated number of deaths attributable to cigarette smoking in Taiwan in 1994 was 8161 (13.9% of total deaths) for men and 1216 (3.3% of total deaths) for women. In the same year cigarette smoking caused 21.3% and 2.9% of cancer deaths in men and women, respectively, in Taiwan. CONCLUSIONS Cigarette smoking has a striking impact on overall mortality and deaths from various causes in the Taiwanese population. Tobacco control should be established as the top priority in public health programmes in Taiwan.