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Secondhand smoke exposure can increase the risk of first ischemic stroke: a 10.7-year prospective cohort study in China

Ru-Mei Lu, Yu-Lu Qin, Changping Xie, Xiaoping Tan, Tingping Zhu, Jinxue Tan, Si-Si Wang, Jiajia Liang et al.

Annals of Epidemiology, 2024

50,174 participants · 6 citations

Abstract

INTRODUCTION

Passive smoking is considered a major public health issue in China. Prospective evidence regarding the link between secondhand smoke (SHS) and ischemic stroke in China is scarce.

METHODS

The China Kadoorie Biobank (CKB) study in Liuzhou City recruited 50,174 participants during 2004-2008. Of these 30,456 never-smokers were included in our study. The median follow-up period was 10.7 years. The incidence of ischemic stroke was obtained through the China Disease Surveillance Points (DSP) system and the Health Insurance (HI) database. Cox proportional risk models were used to evaluate the association between SHS exposure and ischemic stroke.

RESULTS

During 320,678 person-years of follow-up, there were 2,059 patients with ischemic stroke observed and the incidence of ischemic stroke was 6.42 per thousand person-years. Participants exposed to SHS daily faced a 21% higher risk of ischemic stroke (HR=1.21, 95%CI: 1.09-1.34) compared to those exposed to SHS less than once a week. Subgroup analyses revealed that daily SHS exposure was linked to heightened risk of ischemic stroke among women, non-employed, and non-weekly tea drinkers.

CONCLUSIONS

Daily SHS exposure was associated with higher risks of ischemic stroke. Proactive tobacco control strategies are necessary to decrease the risk of ischemic stroke in never smokers.

How strong is the evidence?

Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 50,174 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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