Smoking is bad, quitting is good -- even for Great-Grandma
Most studies on smoking and its well-known health risks have been performed in middle-aged adults (younger than 60). In a large epidemiological study published in the June 11, 2012 Archives of Internal Medicine, Carolin Gellert, Ben Schottker, and Hermann Brenner showed that (spoiler alert!!) smoking's excess risks extend to older adults, as well. Just as importantly, quitting smoking seemed to reduce the risk in people older than age 60 who quit at any age.
Smoking Risk in Older Adults: What They Did
Authors pulled together 17 longitudinal cohort studies from 7 countries published prior to July 2011 considered to be "good quality" according to specified criteria, and combined them into an epidemiologic meta-analysis. Other than randomized trials, longitudinal cohort studies are the best way to confidently identify the risk of an event/outcome over time in association with a particular exposure. In a real-world population, longitudinal cohort studies are the only way to discover this.
Studies had to include people over 60 and study all-cause mortality as the outcome of interest, with the exposure of smoking.
Results were reported as "relative mortality" -- basically, the chance of dying from any cause over a given period, in relation to never-smokers.
What They Found
Smoking is associated with increased all-cause mortality in older people, just like in middle-aged people:
Men over age 60 who were current smokers had a relative mortality (risk of dying from any cause during a given period) somewhere between 1.3 - 3.4 in relation to never-smokers. For currently smoking women, the relative mortality was 1.2 to 2.5.
There was a clear dose-response relationship between number of cigarettes smoked (pack years by self report) and all cause mortality in older current and former smokers (in almost all, but not all the studies that included this information).
Former smokers had an increased relative mortality compared to never-smokers, but significantly less than current smokers: their risk of all-cause mortality was somewhere between 1 (no elevated risk) and 2 (double the risk) in both men and women.
Quitting at any age appeared to save lives: The more years elapsed since quitting smoking, the lower the risk of all-cause mortality, in a clear dose-response relationship. This was based on 5 studies that could quantify age since smoking cessation in former smokers.
What It Means
The increased all-cause mortality from smoking was roughly equal in older people in this meta-analysis as compared to a previous meta-analysis by Shavelle et al in middle-aged people -- smoking approximately doubles the risk of dying from any cause at a particular age.
Possibly the longest longitudinal cohort study to date -- more than 40 years long by Doll et al -- suggested that among smokers that start at a young age, 2 out of 3 will be killed by a smoking-related disease.
Quitting after age 60 could add years to a person's life. Counseling older patients on smoking cessation can feel futile for physicians -- and may be in many cases -- but repeated, broken-record-like reminding of patients to quit smoking on every visit does indeed lead to more people quitting smoking than a nihilistic approach, in studies in outpatient clinics. Adding the information from this study into the counseling spiel would seem like a good idea, to help tip over the psychologically almost-ready older patient into finally quitting smoking for good.
Gellert C et al. Smoking and All-Cause Mortality in Older People: Systematic Review and Meta-analysis. Arch Intern Med 2012;172:837-844.