Objectives: Several studies have shown that smoking may confer a greater excess risk for chronic diseases in women compared with men. The reasons for this excess risk of smoking in women are unclear, yet sex differences in smoking habits may play a role. We, thus, characterised sex differences in smoking habits in a contemporary Western population.
Design: Cross-sectional population-based study. Setting: UK Biobank Resource.
Participants: 499 797 (54% women) individuals with data on smoking habits. Main outcome measures: Women-to-men prevalence ratios in smoking status, and the womenminus- men mean difference in age at smoking initiation, number of cigarettes smoked daily and age at smoking cessation in 5-year birth cohort bands.
Results: The women-to-men ever-smoking ratio ranged from 0.57 in the oldest to 0.87 in the youngest birth cohort. In the oldest cohort, born 1935 1939, women started smoking 1.9 years (95% CI 1.7 to 2.1) later than did men, but in those born after 1959 there was no difference in the age at initiation. The oldest women smoked 5.3 (95% CI 4.7 to 5.9) cigarettes per day fewer than did the oldest men, compared with 2.0 (95% CI 1.7 to 2.3) fewer cigarettes smoked per day in the youngest, born 1965 1969. Among quitters, women born before 1945 were, on average, 1.5 years older than their male contemporaries, but this differential was 1 year or less among people born after 1949. Conclusions: Differences in smoking behaviour between women and men have decreased over time. Even past differentials are unlikely to explain the increased susceptibility to smoking-related chronic disease in women compared with men that has previously been observed. Future studies are required to determine whether sex differences in the physiological and biological effects of smoking are responsible for the differential impact of smoking on health in women and men.
Peters SAE, Huxley RR, Woodward M. Do smoking habits differ between women and men in contemporary Western populations? Evidence from half a million people in the UK Biobank study. BMJ Open 2014;4:e005663. doi:10.1136/bmjopen-2014-005663
Comparisson of smoking behaviour between men and women to assess risk inducing habits
We have recently completed meta-analyses involving millions of subjects, which showed that, although smoking increased risk considerably in both sexes, women who smoke have a 25% greater excess relative risk for coronary heart disease compared to men who smoke. Although not as strong, there is also a trend towards a similar excess risk for stroke among women smokers compared with men. Furthermore, we have published other data, which suggest an excess relative risk of around 100% from smoking for women, compared to men, for lung cancer mortality. One possible reason for these excess relative risks in women is that their smoking habits tend to be more risk-inducing. For example, they may smoke more, or start at a younger age. On the other hand, it may be that women have less risk-inducing smoking habits, in which case the excess relative risks we, and others, have found are even more remarkable, with implications for targeted public health measures to prevent smoking and promote quitting. We request the use of the baseline Biobank data on smoking habits to make comparisons between women and men, so as to understand whether variations in habits may explain the excess relative risks we have found. We shall also explore whether sex differences persist within important subgroups of the Biobank population, by age, self-reported illness, socio-demographic status, and ethnicity. These will all be cross-sectional analyses; in the future we propose to make a further application to investigate whether sex-specific smoking habits contribute to the risk of the major smoking-related chronic diseases using longitudinal Biobank data.
|Lead investigator:||Professor Mark Woodward|
|Lead institution:||George Institute for Global Health|