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Smoking takes at least 10 years off a woman's life reports new study

Robin Wulffson MD's picture
smoking, women, mortality, lung cancer, cardiovascular disease

Smoking is associated with an increased risk of cardiovascular disease, cancer, and other diseases that shorten one’s life span. According to a new study, women who smoke decrease their life span by a decade or more. Researchers affiliated with the University of Oxford in the United Kingdom published their findings online on October 27 in The Lancet.

The researchers note that women born around 1940 in nations such as the UK and USA were the first generation in which many smoked substantial numbers of cigarettes throughout adult life. Thus, only in the 21st Century can the direct effects of prolonged smoking, and of prolonged smoking cessation, on mortality among women in the UK. The researchers recruited 1.3 million UK women from 1996 through 2001 and resurveyed via mail survey approximately three and eight years later. All the women were followed to January 1, 2011 via national mortality records (average: 12 woman-years). The participants were asked at entry whether they were current or ex-smokers, and how many cigarettes they currently smoked. Those who were ex-smokers at both entry and the three-year resurvey and had stopped before the age of 55 years were categorized by the age they had stopped smoking. They computed relative risks that compared categories of smokers or ex-smokers with otherwise similar never-smokers.

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The investigators found that, after excluding 0.1 million women with previous disease, 1.2 million women remained; their average year of birth was 1943 and their average age was 55 years. Overall, 66,489/1,180,652 (6%) died, at an average age of 65 years. At baseline, 232,461 (20%) were current smokers, 328,417 (28%) were ex-smokers, and 619,774 (52%) were never-smokers. For 12-year mortality, those smoking at baseline had a mortality rate ratio of 2.76 compared with never-smokers, even though 37,240/85,256 (44%) of the baseline smokers who responded to the eight-year resurvey had by then stopped smoking. Mortality was tripled, largely irrespective of age, in those still smoking at the three-year resurvey. Even for women smoking fewer than ten cigarettes per day at baseline, 12-year mortality was doubled (rate ratio: 1.98 (range: 1.91 - 2.04)). Of the 30 most common causes of death, 23 were increased significantly in smokers; for lung cancer, the rate ratio was 21.4 (range: 19.7 - 23.2). The excess mortality among smokers (in comparison with never-smokers) was mainly from diseases that, like lung cancer, can be caused by smoking. Among ex-smokers who had stopped permanently at ages 25 to 34 years or at ages 35 to 44 years, the respective relative risks were 1.05 and 1.20 (range: 1.14 – 1.26) for all-cause mortality and 1.84 (range: 1.45 to 2.34) and 3.34 (range: 2.76 – 4.03) for lung cancer mortality. Thus, although some excess mortality remains among these long-term ex-smokers, it is only 3% and 10% of the excess mortality among continuing smokers. If combined with 2010 UK national death rates, tripled mortality rates among smokers indicate 53% of smokers and 22% of never-smokers dying before age 80 years, and an 11-year lifespan difference.

The authors concluded that among UK women, two-thirds of all deaths of smokers in their 50s, 60s, and 70s are caused by smoking; smokers lose at least 10 years of lifespan. Although the hazards of smoking until age 40 years and then stopping are substantial, the hazards of continuing are ten times greater. Stopping before age 40 years (and preferably well before age 40 years) avoids more than 90% of the excess mortality caused by continuing smoking; stopping before age 30 years avoids more than 97% of it.

Take home message:
This study is significant in that it includes the population of Baby Boomers entering golden years. Those who smoke are likely to see their golden years tarnished. Women typically have smaller lungs than men; thus, an equivalent amount of smoking is more detrimental to women.

Reference: The Lancet