Smoking will cause two thirds of smoker deaths rather than the 50% rate that had been suggested by previous research. An Australian study has concluded that smoking regularly could reduce a person’s life expectancy by ten years on average.
The risks of smoking have been well-documented in other countries. The longer a person smokes and the more cigarettes consumed has an impact on life expectancy, bringing risk of cancer, respiratory disease, cardiovascular disease and other health risks. People who stop smoking gain significant health benefits and the earlier they stop, the more those benefits increase.
Although Australia traditionally has a high incidence of smoking among the population, it has had a successful anti-tobacco campaign and in 2013, 13% of adults admitted to being daily smokers. The country had not previously run a smoking-related mortality study and the researchers felt that in the light of previous high prevalence of the habit, that a research study was due.
200 000 people over the age of 45 were recruited into this study. They had no history of cancer other than skin cancer, heart disease, stroke or thrombosis. Respiratory illness which had caused hospital admission in the previous 6 years was excluded.
Some of the participants would have lived through a time where smoking was acceptable, but they would all have witnessed the changes in attitude towards tobacco. Both men and women took part in the research. The study began with a baseline questionnaire which established health behaviour, height and body weight, medical history, socio-demographic factors, functional capacity and physical activity. It also granted permission for access to medical records. 6000 people took part in a resample survey three years later.
The average age at starting smoking for men did not vary greatly whether they were born in 1920-1929 or 1960-1969. It changed from around 18.5 years to 17.5 years. However the age when women started smoking decreased from 24 years down to 17.5 years in the same time period. The average smoking duration of current smokers was 38.5 years, with the majority of smokers reporting having smoked for over 35 years and smoking at least 15 cigarettes a day. Around one third of the resample survey had given up smoking – with those who had been smoking the least amount of cigarettes being more likely to do so.
Compared to non-smokers, the smokers who smoked on average 10 cigarettes a day doubled their risk of death. When the number of cigarettes consumed increased to 25 then the risk of dying was increased fourfold. Some of the evidence suggested that smoking more cigarettes increased women’s risk of dying more than men but during the study, the highest mortality rates belonged to the men.
This large, population-based study is able to be trusted due to its large size and relatively fast follow up on the participants (five years). The heavy incidence of mortality among smokers is a testament to its previous heavy smoking history, but the low incidence of adult smokers currently bodes better for the future generations. However the authors warn that complacency must not ensue and that anti-tobacco measures should continue.
E.Banks, et al, Tobacco smoking and all-cause mortality in a large Australian cohort study: finding from a mature epidemic with current low smoking prevalence; BMC Medicine; 2015; 13:38
Full study available online.