Life expectancy study shows it’s never too late to stop smoking

Quitting smoking even as late as at 75 years of age can meaningfully increase a person’s life expectancy, according to a new study in the American Journal of Preventive Medicine. The research measures the impact of smoking on life expectancy at 10-year intervals from 35–75 years of age to determine the potential benefits of smoking cessation. The results show that although the benefits of quitting smoking diminish with age, there are still substantial gains for older individuals.

Thuy T.T. Le, Ph.D., who conducted the study with co-investigators David Mendez, Ph.D., and Kenneth E. Warner, Ph.D., all affiliated with the Department of Health Management and Policy at the University of Michigan School of Public Health, explains, “We have seen a remarkable decline in young adult smoking over the past decade. However, rates among older adults who smoke have remained stagnant and to our knowledge, no research had established the benefits for them of quitting. We wanted to show that stopping smoking is beneficial at any age and provide an incentive for older people who smoke to quit.”

Cigarette smoke contains thousands of toxic chemicals that harm almost all organs in the body and are linked to numerous cancers, stroke, heart disease, and lung disease. In the United States, cigarette smoking has long been the leading cause of premature preventable death, with an estimated 480,000 smoking-related deaths annually. Previous studies have consistently demonstrated that quitting smoking at any age yields health benefits.

This is the first study to quantify the impact of quitting smoking for individuals older than 65. The investigators used all-cause mortality relative risks due to smoking to build life tables that show the benefits of quitting smoking at different ages. They report the expected life years lost to individuals who smoke at various ages compared to those who never smoked.

Compared to people who never smoked, those who smoke currently, aged 35, 45, 55, 65, or 75 years and who have smoked throughout adulthood until that age, will lose on average, 9.1, 8.3, 7.3, 5.9, and 4.4 years of life, respectively, if they continue to smoke for the rest of their lives. However, if they quit smoking at each of these ages, they will avoid an average loss of 8.0, 5.6, 3.4,1.7, and 0.7 years, respectively. The chances of gaining at least one year of life among those who quit at age 65 are 23.4% and 14.2% at age 75.

This study adds to the body of knowledge supporting the profoundly important assessment that quitting smoking is the single best thing people can do to enhance their life expectancy. Results showed that nearly 10% of individuals who quit at age 65 gain at least 8 years of life compared to those who do not.

Additionally, 8% of those who quit by age 75 gain at least 4 years of life compared to those who continue smoking. Life expectancy for a 75-year-old person who smokes is 9 years. If that person quits, he/she will regain (on average) 0.7 years (7.8% of the life expectancy), and about 8% of those individuals who quit will regain at least 4 years of life (45% of the life expectancy).

Dr. Warner concludes, “The cessation benefit is not limited to young and middle-aged adults who smoke; this study demonstrates its applicability to seniors as well. While the gains from quitting at older ages may seem low in absolute values, they represent a large proportion of an individual’s remaining life expectancy.”