The association of smoking cessation with mortality from pneumonia among middle-aged and elderly community residents: The Japan Collaborative Cohort (JACC) study

Abstract

Several studies have shown that smoking is a significant risk factor for pneumonia, but it is uncertain to what extent smoking cessation reduces the risk. This study aimed to investigate whether and to what extent smoking cessation is associated with reduced risk of mortality from pneumonia in a Japanese, prospective, community-based cohort. We examined 94,972 individuals (mean age, 57 years; women, 57%) who provided valid responses to a lifestyle questionnaire including questions about smoking. We used years of smoking cessation at baseline to divide former smokers into 5 groups: 0–1 year, 2–4 years, 5–9 years, 10–14 years, and 15 years or more. The endpoint was the underlying cause of death from pneumonia. During the median 19-year follow-up of 94,972 study participants, 1806 died from pneumonia. Multivariable hazard ratios (95% confidence intervals) compared with the current smokers were 1.02 (0.72–1.45) for 0–1 year of smoking cessation at baseline, 0.92 (0.70–1.22) for 2–4 years, 0.95 (0.74–1.21) for 5–9 years, 0.71 (0.53–0.96) for 10–14 years, 0.63 (0.48–0.83) for 15 years or more, and 0.50 (0.36–0.70) for never-smokers. Although smoking increases the risk of pneumonia mortality, the present study showed that the risk of pneumonia mortality decreased with years of smoking cessation, eventually improving to levels similar to those of non-smokers for 10 years or more. Continued smoking cessation may be effective in preventing pneumonia deaths.