Death, Not Life, Begins at 40 for Smokers

Abstract & Commentary

By Barbara A. Phillips, MD, MSPH, Professor of Medicine, University of Kentucky; Director, Sleep Disorders Center, Samaritan Hospital, Lexington. Dr. Phillips serves on the speakers bureau for PotomaCME.

Synopsis: Stopping smoking before the age of 40 avoids more than 90% of the excess mortality caused by smoking in women.

Source: Pirie K, et al. The 21st century hazards of smoking and benefits of stopping: A prospective study of one million women in the UK. Lancet 2013;381:133-141.

This study resulted from the million women study,1 which is an on-going British study conducted by the National Health Service. Participants were recruited over a 5-year period and completed questionnaires by mail 3 and 8 years after recruitment. Deaths were ascertained by a national database. Smoking behavior was carefully assessed and categorized, as were multiple confounders, including geographical region, age, body mass index, socioeconomic status, deprivation index, current alcohol intake, physical activity, oral contraceptive use, menopausal status, and hormone replacement therapy use. Although 1.3 million women were recruited, about 0.1 million were excluded because of previous disease or for reasons that the investigators thought might affect the data (for example, women who had had bilateral oophorectomy were excluded from ovarian cancer analysis). The mean age of the participants was 55 years, and 20% were smokers at baseline. Overall, 6% of them died over the 12 years of follow-up. Those who reported smoking at baseline had nearly triple the risk (hazard ratio 2.76) of dying compared with never-smokers, even though nearly half of the women who were smoking at baseline had stopped smoking by the eighth year of follow-up. The excess mortality among smokers (in comparison with never smokers) was mainly from diseases that can be caused by smoking, including lung cancer, COPD, heart disease, and stroke. For those ex-smokers who stopped smoking at ages 25-34 years or at ages 35-44 years, the respective relative risks were 1.05 (95% confidence interval [CI], 1.00-1.11) and 1.20 (CI, 1.14-1.26) for all-cause mortality, and 1.84 (CI, 1.45-2.34) and 3.34 (CI, 2.76-4.03) for lung cancer mortality, respectively. The authors concluded that two-thirds of all deaths of women smokers in their 50s, 60s, and 70s are caused by smoking, and that the loss of lifespan is about 10 years. But stopping before age 40 avoids more than 90% of the excess mortality, while stopping before the age of 30 avoids more than 97% of mortality.

Commentary

As the Surgeon General put it in 1979, “Women who smoke like men die like men who smoke.”2 It was a novel and surprising idea at the time. It is likely that the devastating loss of health and life resulting from smoking by men has already peaked, but smoking prevalence in young women did not peak until the 1960s,3 so most previous studies of women have probably underestimated the full eventual risks of smoking in women. This huge, recent, carefully done study of women drives the point home that we really must continue to advise our female patients who smoke to quit. And earlier is better. For example, based on the science available, the authors did not even analyze the results by pack-years, since having smoked 10 cigarettes a day for 40 years results in a much higher risk of lung cancer at age 60 than having smoked 20 cigarettes a day for the past 20 years. The authors noted that if they did a combined analysis of the current study with 2010 U.K. national death rates, the data indicate that 53% of smokers, but only 22% of never-smokers, die before age 80, an 11-year lifespan difference.

Addressing smoking (or any behavioral health issue) in women is different, and likely easier, than in men. Women of all ages are more likely to seek and follow medical advice than are men, and women of child-bearing years (the group most likely to benefit from smoking cessation) are more likely to interact with health care professionals, particularly around issues of childbirth. Perhaps the values and effective messages are different between men and women. Young men probably need to hear that smoking adversely affects sexual performance,4 but it is likely that young women are more likely to respond to the message that smoking ages their skin.5

References

1. The Million Women Study Collaborative Group. The Million Women Study: Design and characteristics of the study population. Breast Cancer Res 1999;1:73-80.

2. Smoking and Health. A report of the Surgeon General. US Department of Health, Education and Welfare, Office on Smoking and Health, DHEW Publication; No 79-50066:i.

3. Wald N, Nicolaides-Bouman A. UK Smoking Statistics. 2nd ed. Oxford: Oxford University Press; 1991.

4. Mannino DM, et al. Cigarette smoking: An independent risk factor for impotence? Am J Epidemiol 1994; 140:1003-1008.

5. Model D. Smoker’s face: An underrated clinical sign? Br Med J (Clin Res Ed) 1985;291:1760-1762.