Association between allostatic load and asthma in US adults: A nationwide cross-sectional study

Chronic psychosocial stress has been implicated in asthma pathogenesis, but large-scale population-based evidence remains limited. We examined the association between allostatic load (AL) (a composite marker of multisystem physiological dysregulation induced by chronic stress) and asthma prevalence among U.S. adults using National Health and Nutrition Examination Survey 2005 to 2010 data. The allostatic load index (ALI) was calculated from 8 physiological biomarkers representing cardiovascular, metabolic, and inflammatory systems and was categorized as ≤1, 2, and ≥3 for comparative analysis. Asthma was defined by self-reported physician diagnosis. Survey-weighted logistic regression was used to estimate odds ratios (OR) for asthma across ALI categories, adjusting for age, sex, race/ethnicity, socioeconomic indicators, and smoking. Of 15,533 participants (mean age 45.8 years), 2110 (13.6%) reported a history of asthma. Among these individuals, there were 40.57% ALI ≤ 1, 21.0% ALI = 2, and 38.4% ALI ≥ 3. Each 1-unit increase in ALI was associated with a 13% higher odds of asthma (adjusted OR: 1.13, 95% confidence interval [CI]: 1.08-1.18). Compared to those with ALI ≤ 1, the ALI ≥ 3 group was associated with a 45% higher odds of asthma (OR: 1.45, 95% CI: 1.25-1.69, P < .001), with a significant dose-response trend across ALI categories (P for trend < .001). In sensitivity analyses applying clinically defined biomarker thresholds, the results remained robust (adjusted OR for ALI ≥ 3 compared with ALI ≤ 1, 1.62; 95% CI, 1.39-1.89). Subgroup analyses revealed significant effect modification by sex and socioeconomic status: the ALI-asthma association was stronger in women and in individuals with poverty-to-income ratio < 1.3 (interaction P = .01), but was not statistically significant in men. Associations remained consistent across age, race/ethnicity, smoking status, and education. These findings indicate that cumulative biological stress, as indexed by AL, is associated with asthma in U.S. adults, particularly among women and socioeconomically disadvantaged populations. Incorporating AL into asthma risk assessment may improve identification of high-risk individuals and guide upstream interventions targeting chronic stress. Addressing chronic stress and social determinants of health may be important strategies for reducing asthma burden.