The School of Public Health of The University of Hong Kong Li Ka Shing Faculty of Medicine has conducted a 10-year follow-up study based on 18 Elderly Health Centres of Department of Health and found that, among older smokers aged 65-84, one out of three were killed by smoking. The risks of lung cancer and coronary heart disease (CHD) mortality are increased by 277% and 35% respectively compared to never smokers. On the other hand, the risks of all-cause (deaths from any causes), lung cancer and CHD mortality in former older smokers (quitters) are significantly reduced.

The results demonstrate that, older people should quit smoking immediately to reduce the health risks and improve survival. This study is the first and largest follow-up study on the association of smoking, quitting and mortality in older people in Hong Kong. The results provide strong scientific evidence to support the increase in tobacco tax to encourage smoking cessation and improve health of the older people.

Research Methodology
Based on the data gathered from 18 Elderly Health Centres of Department of Health, a total of 64,654 older people who were aged 65-84 and first enrolled to the Centres during 1998 to 2001 were followed up. Information on smoking and other risk factors was collected by interviews, and death or causes of death were obtained from the Deaths Registries. The older people were followed up for about 10 years on average, so as to find out the association of smoking, quitting and mortality in older people in Hong Kong.

Research findings
Up to October 2010, among the over 60,000 older subjects, 14,438 deaths (22.3%) were observed. Compared to never smokers, the risks of all-cause, lung cancer and CHD mortality in current older smokers are increased by 55%, 277% and 35% respectively. On the other hand, compared to current older smokers, the risks of all-cause, lung cancer and CHD mortality in former older smokers are reduced by 4%, 32% and 7% respectively.

The study also shows that, among the older smokers, there are 27.8 deaths per year per 1,000 persons, which is at much higher rate than that among the never smokers (17.9 deaths per year per 1,000 persons).

Conclusion
According to previous studies, of every 4 smokers who started smoking in their adolescence, 2 will die of smoking-induced diseases. Of these 2 deaths, 1 dies in middle age and the other dies in older age. As this study finds that of every 3 older smokers, 1 will be killed by smoking-induced diseases, it further confirms the accuracy of the above mentioned argument in previous studies.

This study also shows a significant risk reduction of lung cancer mortality from quitting smoking. Previous studies found that, the earlier and longer the quitting, the more reduction in mortality risk. The risk reduction of all-cause mortality is relatively low in this study, probably because the former older smokers quitted smoking too late or quitted after having serious diseases. Hence, older people should quit smoking immediately to reduce mortality and improve survival as soon as possible. Increasing tobacco tax will encourage the older people to cease smoking and ultimately gain better health.

About the Research Team
This study was conducted by Professor Lam Tai-hing and Ms Xu Lin, a PhD candidate, of the School of Public Health, The University of Hong Kong Li Ka Shing Faculty of Medicine.