Has the impact of cigarette smoking on mortality been underestimated by overlooking second-hand smoke? Tohoku medical megabank community-based cohort study
Objectives Previous studies have assessed the impact of active smoking on mortality using the population-attributable fraction (PAF). However, these studies have not included second-hand smoking (SHS), potentially underestimating smoking’s impact. We compared the PAF from active smoking alone with t...
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
BMJ Publishing Group
2025-01-01
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| Series: | BMJ Public Health |
| Online Access: | https://bmjpublichealth.bmj.com/content/3/1/e001746.full |
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| Summary: | Objectives Previous studies have assessed the impact of active smoking on mortality using the population-attributable fraction (PAF). However, these studies have not included second-hand smoking (SHS), potentially underestimating smoking’s impact. We compared the PAF from active smoking alone with the PAF, including SHS exposure.Design Prospective cohort study.Setting A community-based cohort study in Japan.Participants 40 796 participants aged ≥20 years.Main outcome measures SHS was defined as inhaling someone else’s cigarette smoke at the workplace or home in the past year. We classified smoking status and SHS into ten categories: never-smoker without SHS, never-smoker with SHS, past smoker without SHS, past smoker with SHS, current smoker 1–9 cigarettes/day without SHS, current smoker 1–9 cigarettes/day with SHS, 10–19 cigarettes/day without SHS, 10–19 cigarettes/day with SHS, ≥20 cigarettes/day without SHS and ≥20 cigarettes/day with SHS. The main outcome was all-cause mortality.Results During the median follow-up period of 6.5 (5.7–7.5) years, 788 men and 328 women died. For men, compared with never-smokers without SHS, past smokers without SHS (HR, 1.39 [95% CI, 1.11 to 1.73]) and past smokers with SHS (HR, 1.48 (95% CI, 1.10 to 2.00)) were associated with all-cause mortality. For women, never-smokers with SHS had a significantly higher risk of all-cause mortality (HR, 1.36 (95% CI, 1.00 to 1.84)). Without considering SHS, 28.0% and 2.3% of all-cause mortality in men and women, respectively, were attributable to past and current smoking. Including SHS, PAF increased to 31.3% in men and 8.4% in women.Conclusions We clarified that smoking’s impact was underestimated by not accounting for SHS, especially in women. Information on SHS is crucial for understanding smoking’s health impact. This study supports the importance of avoiding smoking and preventing SHS. |
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| ISSN: | 2753-4294 |