TABLE 1

Demographics and baseline disease severity

Low-income smokers (<USD15000 per year)Higher-income smokers (>USD15000 per year)p-value
Subjects n15493277
Age years55.7±7.461.7±8.5)<0.0001
African American5716<0.0001
Male49520.031
BMI kg·m−229.1±6.729.1±5.70.95
More than high-school education4577<0.0001
ATS pack-years42.5±25.042.2±22.60.66
Age started smoking years16.7±5.117.2±4.10.0016
Current smoking status7336<0.0001
Using respiratory medications4231<0.0001
FEV1 % pred78.4±23.280.4±23.00.0042
FVC % pred87.7±17.889.6±16.50.0002
FEV1/FVC0.70±0.140.68±0.140.0003
Percentage emphysema LAA@-950HU4.68±7.66.24±8.9<0.0001
Percentage gas trapping LAA@-856HU19.3±17.920.5±17.80.0652
Airway wall thickness mm1.063±0.2311.018±0.211<0.0001

Data are presented as mean±sd or %, unless otherwise stated. BMI: body mass index; ATS: American Thoracic Society; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; LAA: low-attenuation areas.