Smoking, quitting and mortality in an elderly cohort of 56 000 Hong Kong Chinese

Background: Although the harms of smoking are well established, it is unclear how they extend into old age in the Chinese. Aim: To examine the relationship of smoking with all-cause and major cause-specific mortality in elderly Chinese men and women, respectively, in Hong Kong. Methods: Mortality by smoking status was examined in a prospective cohort study of 56 167 (18 749 men, 37 416 women) Chinese aged ≥65 years enrolled from 1998 to 2000 at all the 18 elderly health centres of the Hong Kong Government Department of Health. Results: After a mean follow-up of 4.1 years, 1848 male and 2035 female deaths occured among 54 214 subjects (96.5% successful follow-up). At baseline, more men than women were current smokers (20.3% vs 4.0%) and former smokers (40.8% vs 7.9%). The adjusted RRs (95% Cl) for all-cause mortality in former and current smokers, compared with never smokers, were 1.39 (1.23 to 1.56) and 1.75 (1.53 to 2.00) in men and 1.43 (1.25 to 1.64) and 1.38 (1.14 to 1.68) in women, respectively. For current smokers, the RRs (95% Cl) for all-cause mortality were 1.59 (1.39 to 1.82), 1.72 (1.48 to 2.00) and 1.84 (1.43 to 2.35) for daily consumption of 1-9, 10-20 and >21 cigarettes, respectively (p for trend <0.001). RRs (95% Cl) were 1.49 (1.30 to 1.72) and 2.20 (1.88 to 2.57) in former and current smokers for all deaths from cancer, and 1.24 (1.04 to 1.47) and 1.57 (1.28 to 1.94) for all cardiovascular deaths, respectively. Quitters had significantly lower risks of death than current smokers from all causes, lung cancer, all cancers, stroke and all cardiovascular diseases. Conclusions: In old age, smoking continues to be a major cause of death, and quitting is beneficial. Smoking cessation is urgently needed in rapidly ageing populations in the East.