If you cannot quit abruptly, only “reduction” of smoking will be of benefit to you !

著者名:Gerber Y.et al.
文献タイトル:Smoking reduction at midlife and lifetime mortality risk in men a prospective cohort study. 
雑誌名・書籍名:Am J Epidemiol.
発行年:2012 May 15;175(10):1006-12.

Previous studies have not shown a survival advantage for smoking reduction. The authors assessed survival and life expectancy according to changes in smoking intensity in a cohort of Israeli working men. 

Baseline smokers recruited in 1963 were reassessed in 1965 (n = 4,633; mean age, 51 years). Smoking behavior was self-reported (5 status : never smoker / past smoker / 1-10 / 11-20 / more than 20 cigarettes per days) respectively. They were followed up prospectively for mortality through 2005. Smoking intensity at both time points was self-reported and categorized as none, 1-10, 11-20, and ≥21 cigarettes per day. 

Change between smoking categories was noted, and participants were classified as increased (8%), maintained (65%), reduced (17%), or quit (10%) smoking (Table 1). During a median follow-up of 26 (quartiles 1-3: 16-35) years, 87% of participants died. Changes in intensity were associated with survival. In multivariable-adjusted models, the hazard ratios for mortality were 1.14 (95% confidence interval (CI): 0.99, 1.32) among increasers, 0.85 (95% CI: 0.77, 0.95) among reducers, and 0.78 (95% CI: 0.69, 0.89) among quitters, compared with maintainers (Table 3). Inversely, the adjusted odds ratios of surviving to age 80 years were 0.77 (95% CI: 0.60, 0.98), 1.22 (95% CI: 1.01, 1.47), and 1.33 (95% CI: 1.07, 1.66), respectively. The survival benefit associated with smoking reduction was mostly evident among heavy smokers and for cardiovascular disease mortality. 

These results suggest that decreasing smoking intensity should be considered as a risk-reduction strategy for heavy smokers who cannot quit abruptly.

・No information is available on smoking habits throughout follow-up.
・There was more factors that should adjusted detail. For example dietary and physical activity patterns.
・This study is a male-only cohort.