By: Dr. Geoffrey Modest
A recent combination of many large cohort observational studies assessed the role of smoking on mortality, looking beyond the accepted 21 smoking-related diseases (see N Engl J Med 2015;372:631-40.)
Background:
–current smokers have 2-3x the mortality of never-smokers
–the 2014 Surgeon General’s report estimated that >480K deaths/year in the US are smoking related, but considered only those deaths from those 21 acknowledged diseases
–the 21 diseases are the usual culprits: the 5 most common are lung cancer, COPD, ischemic heart disease, “other heart disease”, and total stroke (ischemic and hemorrhagic). Others include less common cancers (esophageal, stomach, lip/oral cavity, liver, colorectal, bladder, kidney and acute myelogenous leukemia), other atherosclerotic issues (aortic aneurysm and “other arterial diseases”), and infections (pneumonia, influenza, TB).
–the researchers looked at people >55 yo from 5 large US cohorts: Cancer Prevention Study II Nutrition cohort, Nurses’ Health Study I cohort, Health Professionals Follow-up Study cohort, Women’s Health Initiative cohort and National Institutes of Health — AARP Diet and Health Study Cohort. Of these, the NIH-AARP provided about 75% of the male data and the NIH-AARP and WHI each provided >30% of the female data.
–total of 421,378 men and 532,651 women were followed from 2000-2011, mean age 65, 92% white, 50% drinkers, 9% current smokers and 50% former smokers.
Results:
–total deaths 181,377, including 16,475 current smokers
–17% of the excess mortality was not in the 21 diseases per the US Surgeon General, with the most significant increases in current smokers for:
–renal failure, RR=2.0
–intestinal ischemia, RR=6.0
–hypertensive heart diseease, RR=2.4
–infections, RR=2.3
–various respiratory diseases, RR=2.0
–breast cancer, RR=1.3
–prostate cancer, RR=1.4
–others, though smaller numbers of deaths overall, included liver cirrhosis (RR=2.6), cancers of unknown site (RR=3.0), essential hypertension and hypertensive renal disease (RR=2.5)
–the specific death rates in general also increased with number of cigarettes smoked daily
–in general, the rates were increased in former smokers, with the RR declining as the number of years since quitting increased
–all of above associations were adjusted for current alcohol consumption. but as a side analysis looking at non-drinking smokers, the RR of liver cirrhosis still had RR=2.0 (somewhat lower), but for breast cancer was unchanged at 1.4
Conclusion: if one were to include these excess smoking-related deaths, the attributable annual mortality would be >60K more than the Surgeon General would have estimated by the 21 identified diseases
So, even more reason to not smoke, or to stop (and the sooner, the better). One can speculate about the mechanisms (eg, is death from renal failure from atherosclerotic disease, or the known dose-dependent increase in albuminuria?, is increased infections related to immune dysfunction, locally and/or systemically?). But, bottom line, smoking is not good for your health….. (and the above give us even more issues to discuss with patients)