Abstract Rationale Youth with obesity-related asthma have worse asthma morbidity than their peers without obesity. Obesity has been associated with airway dysanapsis (an incongruency between the caliber of airways and the volume of the lungs), which in turn is associated with worse asthma outcomes. However, it is not known whether dysanapsis is driven by body mass index (BMI) or by other measures of adiposity and body composition. We hypothesized that adiposity distribution would be significantly associated with airway dysanapsis. Methods We analyzed data from the Genomics of Obesity-Related Asthma study (GenOAAT), a cohort of youths ages 6-20 years, with and without asthma. Anthropometric measurements included BMI, waist and hip circumferences, subscapular and tricipital skin fold thickness, and percent body fat (PBF) and basal metabolic rate (BMR) measured by bioimpedance. Dysanapsis was defined as a high FVC (100% of predicted), normal FEV1 (80% pred), and low FEV1/FVC (80% pred). The dysanapsis ratio (DR) was calculated as FEF25-75%/FVC (where dysanapsis = lower DR). We used multivariable linear or logistic regression models adjusted for age, sex, race, and asthma status to obtain odds ratios (ORs) or mean differences (MDs) and 95% confidence intervals (CIs). Results We analyzed data from 139 GenOAAT participants (mean age=14.1 ± 2.97 years, 46% female, 82% White, mean BMI z-score=0.99), including 68 with asthma and 32 who met the definition of airway dysanapsis. BMI z-score showed a near-significant trend for higher odds of dysanapsis (OR = 1.29; 95%CI=0.99-1.73; p = 0.06), while BMR z-score was significantly associated (OR = 1.37; 95%CI=1.04-1.84; p = 0.03) (Figure 1a). Higher anthropometric and metabolic indices were associated with lower dysanapsis ratio (Figure 1b): a 1.0 increment in BMI z-score was associated with 4.5% lower DR (95%CI:-7.06, -1.94; p 0.001); BMR z-score associated with 3.5% lower DR (95%CI: -6.2, -0.69; p = 0.02); waist circumference z-score with 3.3% lower DR (95%CI: -5.94, -0.64; p = 0.02); and waist-to-height z-score with 3.2% lower DR (95%CI: -5.85, -0.61; p = 0.02). Conclusion In our cohort of youth with and without asthma, anthropometric and bioimpedance measurements of central adiposity -more so than markers of general adiposity- are associated with airway dysanapsis. We will continue to characterize the associations between body composition, fat distribution, and airway dysanapsis to improve our understanding of this phenotype of airflow limitation. This abstract is funded by: NIH grant HL149693
Unruh et al. (Fri,) studied this question.