Abstract
INTRODUCTION: Asthma drives significant healthcare use, including frequent emergency department (ED) visits in the US. Modifiable factors like overweight/obesity and smoking exacerbate the disease through inflammation and reduced treatment efficacy. Their combined link to the burden of current symptoms in adults requires further study. This study used nationally representative data to investigate the independent and synergistic associations of overweight and smoking history with current asthma symptoms among United States adults, specifically examining potential gender differences. METHODS: This cross-sectional study conducted a pooled analysis of secondary data from 1655 participants in the 2015-2016 and 2017-2018 cycles of the National Health and Nutrition Examination Survey (NHANES). The outcome was current asthma symptoms, defined by a positive response to the question 'Do you still have asthma?', among those ever diagnosed. Exposures were overweight (body mass index, BMI ≥25 kg/m(2)) and ever smoking (≥100 cigarettes in lifetime). Multivariable logistic regression models adjusted for age and gender were used to assess associations. RESULTS: Among 1655 participants (mean age 46.5 years), 999 (60.4%) reported current asthma symptoms. In the fully adjusted model, both overweight (adjusted odds ratio, AOR=1.42; 95% CI: 1.12-1.79) and smoking history (AOR=1.27; 95% CI: 1.03-1.57) were independently associated with higher odds of current asthma symptoms. Notable gender differences were observed: these associations were significant and strong in women (overweight, AOR=1.89; smoking, AOR=1.41) but absent in men. No significant interaction between overweight and smoking was detected (interaction p=0.580). CONCLUSIONS: Overweight and smoking are independent, modifiable predictors associated with current asthma symptoms in US adults, with a disproportionately strong effect observed in women. These findings identify a symptomatic profile that is associated with the likelihood of exacerbations. This profile may help inform clinical attention and future research aimed at reducing asthma morbidity and potential ED visits.