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

Close associations among secondhand smoke (SHS) and metabolic syndrome (MetS) and its components have been demonstrated, however sex differences in these associations remain unclear. We collected 121,364 participants from the Taiwan Biobank, and excluded those with smoking history, the remaining 88,297 participants (male: 18,595; female: 69,702; mean age 50.1 ± 11.0 years) were included. SHS exposure was evaluated based on self-reported questionnaires. SHS was associated with MetS (odds ratio [OR], 1.268, p < 0.001 for males vs. 1.180, p < 0.001 for females), abdominal obesity (OR, 1.234, p < 0.001 for males vs. 1.199, p < 0.001 for females), low high-density lipoprotein cholesterol (OR, 1.183, p = 0.008 for males vs. 1.094, p = 0.011 for females), hyperglycemia (OR, 1.286, p < 0.001 for males vs. 1.234, p < 0.001 for females), but not with hypertriglyceridemia. SHS was associated with high blood pressure (BP) (OR, 1.278, p < 0.001) only in males, but not in females. Furthermore, significant interactions were found between sex x SHS on MetS (p = 0.023), abdominal obesity (p = 0.032), and elevated BP (p < 0.001). Moreover, the participants who were exposed to SHS for ≥1 hour per week were associated with a higher risk (OR = 1.316, p = 0.001 in males vs. OR = 1.220, p < 0.001 in females) of MetS compared to those with no exposure. These results showed an association between SHS and a high OR for MetS in both the males and females. Furthermore, sex differences were identified in the associations between SHS and MetS and its components, and SHS was more closely related to MetS, abdominal obesity, and high BP in males than in females.