Association between asthma, obesity, and metabolic syndrome in adolescents and young adults

Background: The association of asthma and metabolic syndrome (MetS) among adolescents and young adults (AYAs) remains unclear, as well as the role of obesity in this relationship. Methods: AYAs aged 12-25 years who participated in the 2011–2020 National Health and Nutrition Examination Survey were included in this cross-sectional analysis. The moderating effect of obesity (age- and sex-adjusted body mass index ≥ 95th%ile for adolescents or ≥ 30 kg/m² for adults) on asthma and MetS were evaluated in four groups: 1) both asthma and obesity; 2) asthma and no obesity; 3) obesity and no asthma; and 4) healthy controls with no obesity/asthma. Results: A total of 7,709 AYAs (53.9% aged 12–18 years, 51.1% males, and 54.4% non-Hispanic White) were included in this analysis. 3.6% (95% CI 2.8–4.3%) had obesity and asthma, 7.6% (95% CI 6.8–8.4%) had asthma and no obesity, 21.4% (95% CI 19.6-23.2%) had obesity and no asthma, and 67.4% (95% CI 65.4–69.4%) had neither obesity nor asthma. The estimated prevalence of MetS was greater among those with both obesity and asthma versus those with only asthma (4.5% [95% CI 1.7–7.3%] vs. 0.2% [95% CI 0–0.5%], p < 0.001). Compared to healthy controls, those with both obesity and asthma had ∼10 times higher odds of having MetS (aOR 10.5, 95% CI 3.9–28.1). Conclusions: Our results show the association between MetS and asthma is stronger in AYAs with BMI-defined obesity. Efforts to prevent and treat obesity may reduce MetS occurrence in AYAs with asthma.