How to avoid premature death if you are a smoker
Worldwide, smoking is a major cause of premature death; however, it has declined substantially among adults in the United States. Despite this decline, estimates based on extrapolation from studies in the 1980s suggest that for those between 35 and 69 years of age, smoking currently accounts for almost 200,000 deaths annually in the US, or about one fourth of all deaths in this age group. A new study attempted to determine the current health impact of smoking in the US as well as methods to decrease it. An international team of researchers published their findings on January 24 in the New England Journal of medicine.
The study group comprised 113,752 women and 88,496 men 25 years of age or older who were interviewed between 1997 and 2004 in the US National Health Interview Survey (NHIS). The NHIS sampling frame excludes only about 7 million adults (primarily patients in long-term care facilities, prisoners, and active-duty military personnel) from the total US domestic population of 226 million adults in 2004. Enrollment rates for women exceeded those of men. Smoking and smoking-cessation histories were obtained from the subjects and that data was correlated to the causes of deaths that occurred by December 31, 2006 (8,236 deaths in women and 7,479 deaths in men). Hazard ratios for death among current smokers, as compared with those who had never smoked, were adjusted for age, educational level, adiposity, and alcohol consumption.
Current smokers more commonly consumed alcohol, had lower educational levels, and had a lower body-mass index (BMI) than did former smokers or those who had never smoked. Approximately two thirds of current smokers and of former smokers had started smoking before 20 years of age. The proportion of former smokers increased sharply with age; therefore, they were, on average, older than current smokers and those who had never smoked. Cessation of smoking was less common among women than among men; the ratio of former smokers to current smokers at 65 to 69 years of age was 2:1 for women but 4:1 for men.
The researchers found that for participants who were 25 to 79 years of age, the rate of death from any cause among current smokers was about three times that among those who had never smoked (hazard ratio for women: 3.0; hazard ratio for men: 2.8; 99% CI). They noted that most of the excess mortality among smokers was due to neoplastic (cancer), vascular (blood vessel), respiratory (lungs), and other diseases that can be caused by smoking. The probability of surviving from 25 to 79 years of age was approximately twice as high in individuals who had never smoked, compared to current smokers (70% vs. 38% among women; 61% vs. 26% among men). Compared to individuals who never smoked, life expectancy was shortened by more than 10 years among the current smokers. Compared to individuals who continued to smoke, adults who had quit smoking at 25 to 34, 35 to 44, or 45 to 54 years of age gained about 10, 9, and 6 years of life, respectively.
The authors concluded that, compared to individuals who never smoked, smokers lose at least one decade of life expectancy. They stressed that cessation before the age of 40 years reduces the risk of death associated with continued smoking by about 90%.