Airway tree caliber across the adult lifespan

Rationale: Lung function peaks in early adulthood and declines thereafter. We hypothesized that increasing age would be associated with smaller airway tree caliber across the adult lifespan. Methods: A sample of non-smoking adults age 20 to 97 years old free of clinical lung disease was created by harmonization of four studies: MESA Lung, CanCOLD, SPIROMICS, and the Iowa Computed Tomography (CT) Study which performed computed tomography to quantify airway lumen diameters and total lung volume. Airway tree caliber was quantified as the mean of 19 airway lumen diameters at standard locations (trachea-to-subsegments) in standardized units. Sex-specific airway tree caliber regression models were fit with restricted cubic spline terms for age, body height and total lung volume. Age and airway tree caliber relationship was assessed while keeping body height and total lung volume fixed. Sensitivity analyses stratified by sex, study, scanner, and race-ethnicity. Results: Among 1,056 participants (median [range] age: 67 [20-97] years, 57% female), increasing age from 20 to 50 years was associated with larger airway caliber followed by a plateau (Figure). Compared with aged 51-60 years, participants aged 20-30, 31-40, and 41-50 years exhibited mean standardized differences in caliber of -0.53, -0.33 and -0.13 SD respectively with p<0.001. Sensitivity analyses were consistent. Conclusion: Increasing age from early to mid-adulthood was associated with larger airway tree caliber