Clinical Question: Is an increased rate of infection another argument to encourage smokers to quit?

Setting: Outpatient (any)

Study Design: Systematic review

Synopsis: The authors of this systematic review searched MEDLINE for articles on the mechanisms and epidemiology of smoking-related infectious disease. Pneumococcal pneumonia is related to smoking, especially in patients with chronic obstructive pulmonary disease. In a population-based survey in Texas, smokers comprised 47 percent of the patients with invasive pneumococcal disease, although smokers typically comprise only 23 percent of the population.

In two case-control studies, adult smokers were two to four times more likely to develop invasive pneumococcal disease or pneumonia than similar nonsmoking adults (odds ratio [OR] in the two studies = 1.9 to 4.1). Smokers are seven times more likely than nonsmokers to develop legionnaires’ disease (OR = 3.5; 95 percent confidence interval [CI], 3.3 to 17). Cigarette smoking also is associated with meningococcal disease. In one study of a meningococcal disease outbreak among college students, smokers were almost eight times more likely to become infected than nonsmokers, although the exact estimate is imprecise (OR = 7.8; 95 percent CI, 1.3 to 64).

Exposure to secondhand smoke is associated, in a dose-related manner (the amount of smoking by the parents), with children developing meningococcal disease. Otitis media occurs more frequently in children of smoking parents (OR = 1.9; 95 percent CI, 1.0 to 3.5), although the clinical course is similar between the two groups. In another study, smoking during pregnancy predicted subsequent ear infections in children in a dose-related fashion. Periodontal disease is 2.5 to six times more common in smokers (again, in a dose-related manner) and is more severe. Gastric and duodenal ulcers are more likely in smokers. As is already well known, the common cold, influenza, and tuberculosis occur more often in smokers.

Bottom Line: The list of infections that occur more commonly in smokers is long and not limited to the respiratory tract. Colds, pneumonia, tuberculosis, and influenza are more common in smokers, as is legionnaires’ disease. Meningococcal disease, periodontal disease, and ulcers occur more frequently in smokers. In children of parents who smoke, especially mothers who smoke, otitis media occurs more frequently. All of these diagnoses present another opportunity to counsel patients that their lives would be better without cigarettes. (Level of Evidence: 2b)