Association between Secondhand Smoke Exposure and Metabolic Syndrome in 118,609 Korean Never Smokers Verified by Self-Reported Questionnaire and Urine Cotinine

Abstract

Background: No study has reported the association between secondhand smoke (SHS) exposure and metabolic syndrome (MetS) in self-reported never smokers verified by both self-reported questionnaire and urine cotinine.Methods: A total of 118,609 self-reported and cotinine-verified never smokers (38,385 male; age 34.8±7.1 years) who participated in the Kangbuk Samsung Health Study between 2011 and 2016 were included. Cotinine-verified never smokers were defined as individuals with urinary cotinine <50 ng/mL. SHS exposure was defined as current exposure to passive smoking indoors at home or workplace.Results: Prevalence of SHS exposure in the overall population was 22.6% (27.4% for males and 20.3% for females (<i>P</i><0.001). The overall prevalence of MetS was 6.8% and was higher in males than in females (10.7% vs. 4.9%, <i>P</i><0.001). In both genders, MetS prevalence was higher in the SHS exposure group than the non-SHS exposure group (11.3% vs. 10.4%, <i>P</i>=0.010 for males; 5.8% vs. 4.6%, <i>P</i><0.001 for females). However, there was significant gender interaction for the association between SHS exposure and MetS (<i>P</i> for interaction=0.010). In the multivariate regression analyses, SHS exposure was associated with increased MetS odds only in females (odds ratio [95% confidence interval], 1.02 [0.94 to 1.11] in male vs. 1.17 [1.06 to 1.29] in female). In particular, females with SHS exposure of ≥1 hour/day and ≥3 times showed increased odds of MetS compared with those without SHS exposure (1.22 [1.02 to 1.45], 1.30 [1.14 to 1.49]).Conclusion: This cross-sectional study showed that SHS exposure was significantly associated with prevalence of MetS in self-reported and cotinine-verified female never smokers.

Sex difference in the associations among secondhand smoke with metabolic syndrome in non-smokers in a large Taiwanese population follow-up study

“…Our finding of an association between SHS and a high OR for MetS in both the male and female participants is important. A previous study 8 of 118,609 Korean participants over 18 years of age who self-reported that they were never-smokers and were verified through urinary cotinine analysis investigated the associations among SHS exposure, sex and prevalence of MetS, and reported a notably higher prevalence of MetS in both males and females exposed to SHS compared to those without exposure. In another large longitudinal study 22 of 71,055 non-smokers without MetS at baseline, the subjects were classified into continuous, former, new and no exposure to environmental tobacco smoke (ETS) groups.…”

“…Exposure to secondhand smoke (SHS) is defined as currently being exposed to passive smoking indoors in the workplace or at home 8 . Tobacco smoke comprises many components, of which 20 carcinogens, and in particular polycyclic aromatic hydrocarbons and the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, are considered to play major roles in the development of lung cancer 9 .…”

“…Moreover, Kim et al identified sex interactions in the association between SHS exposure and MetS. Their results indicated that female never-smokers had higher risks of all five MetS components if they had been exposed to SHS in comparison to those without exposure to SHS, while this was not found in male never-smokers 8 .…”

Combined Influence of Eight Lifestyle Factors on Metabolic Syndrome Incidence: A Prospective Cohort Study from the MECH-HK Study

“…A previous meta-analysis highlighted that active smokers, including both current and former smokers, demonstrated an increased incidence of MetS compared to individuals who never smoked, with a pooled relative risk (RR) and 95% confidence interval (95% CI) of 1.26 (1.10–1.44) [ 5 ]. Additionally, findings from a Korean cohort study revealed a higher prevalence of MetS among women exposed to secondhand smoke than individuals who never smoked (5.8% vs. 4.6%; odds ratio (OR) = 1.17; 95% CI = 1.06–1.29; p < 0.001) [ 6 ]. Therefore, in this study, individuals who had never smoked and those not exposed to secondhand smoke were categorized into the healthy group (1 point).…”

“…Previous investigations have revealed significant associations between individual lifestyles and MetS. For example, both active smoking and secondhand smoke exposure were positively associated with MetS [ 5 , 6 ]. A meta-analysis demonstrated that an increase of 10 metabolic equivalent of task (MET) h/week in leisure-time physical activity correlated with an 8% reduction in MetS incidence [ 7 ].…”