Smoking is a known risk factor for many chronic diseases, including cardiovascular disease and cancer, but the epidemiological evidence mostly has relied on studies conducted among middle-aged adults, according to background information in the study, which appears in the June 11 issue of the Archives of Internal Medicine.
Researchers with the German Cancer Research Center in Heidelberg, Germany, identified 17 studies published between 1987 and 2011 in seven countries (the U.S., China, Australia, Japan, England, Spain and France). The follow-up time of the studies ranged from three to 50 years, and the size of the study populations ranged from 863 to 877,243 participants, most of whom were ages 60 and older.
In summarizing the results from the 17 studies, the authors noted an 83% increased relative mortality for current smokers and a 34% increased relative mortality for former smokers compared with people who never smoked.
“This review and meta-analysis demonstrates that the relative risk for death notably decreases with time since smoking even at older age,” the authors wrote.
In a commentary, Tai Hing Lam, MD, of the University of Hong Kong, wrote: “Most smokers grossly underestimate their own risks. Many older smokers misbelieve that they are too old to quit or too old to benefit from quitting.
“Because of reverse causality and from seeing deaths of old friends who had quit recently, some misbelieve that quitting could be harmful. A simple, direct, strong and evidence-based warning is needed.”