Association of Obesity with Quantitative Chest CT Measured Airway Wall Thickness in WTC Workers with Lower Airway Disease

Cluster Analysis of World Trade Center Related Lower Airway Diseases

“…Given those results with cluster 4, Pi10, as well as other airway imaging metrics, deserve further investigation in the WTC cohort, as studies have shown its association with persistent chronic bronchitis, 52 and possibly with more adverse but possibly preventable long-term functional outcomes. Cluster 4 also showed weight gain, and our previous studies had suggested the association of obesity 12 and weight gain 10 with quantitative CT markers of airway inflammation, and accelerated longitudinal expiratory flow decline, respectively. While cluster 4 had the highest proportion of current and former smokers, our studies have shown the remarkable success of smoking cessation interventions in this cohort.…”

“…We also considered 6 bronchodilator response (BDR) at any visit, most often the baseline, defined as an increase in either FEV 1 or FVC of at least 12% and 200 mL in response to inhaled albuterol administration 7,10 ; body mass index (BMI) in kilograms per square meter measured at the baseline visit 8 ; weight gain (as indicated by longitudinal measured BMI trajectory (BMIslope) in kilograms per square meter per year 10 ). Lastly, from the QCT data, 9 total lung volume (TLV CT ), with calculated predicted values 28 and assessed by z scores, 10 lung attenuation volume percent, either high (HAV% from −600 to −250 Hounsfield units [HU], with >10% as cut point) and low (LAV% less than −950 HU, low attenuation volume percent, with >2.5% as cut point), 4,29 indirect distal airway measurements such as 11 end-expiratory air trapping at −856 HU (AT EXP 856), 8,29 and 12 mean expiratory:inspiratory lung density ratio (MLD EI ), 8 and proximal airway metrics such as 13 wall area percent (WAP) directly measured on the third generation of the right upper lobe, 8,10,29 and 14 Pi10, the average wall thickness of a hypothetical airway with a 10-mm luminal perimeter on CT 29,30 …”

“…and A.P.R.). 4,8,[10][11][12] We selected spirometries that met our quality selection requirement, namely, forced exhalatory time >6 seconds and overall spirometry (reproducibility) grades A, B, or (if at least five trials were available) C. 2,8,23 As previously reported, 23 our spirometry program quality assurance included both daily inspiratory and expiratory volume calibration checks and weekly expiratory linearity checks.…”

“…Among workers engaged in rescue and recovery efforts, occupational exposures to dust and fumes at the World Trade Center (WTC) disaster site have been associated with lower respiratory symptoms, 1 worse lung function 2 and accelerated longitudinal lung function decline trajectories, 3,4 asthma 5 and other chronic airway diseases, 6–8 and both qualitative 9 and quantitative 4,8,10–12 abnormalities on computed tomography (CT) of the chest. Common co-existing morbidities, such as obesity, are linked to greater severity of WTC-related respiratory symptoms, airway disorders, and morbidity 13–19 …”