TABLE 1

Patient demographics

Never-smokersSmokers without COPDCOPDOverall p-value
GOLD stage IGOLD stage II–III#GOLD stage IV
Patients8971815
Male/female2/63/64/313/55/10
Age years66 (33–76)58 (47–68)69 (56–75)70 (53–75)ƒ62 (53–66)##0.015
Height m1.6 (1.5–1.8)1.7 (1.6–1.8)1.7 (1.6–1.8)1.7 (1.5–1.9)1.7 (1.5–1.9)0.276
BMI kg·m−222.6 (19.8–29.7)23.4 (19.7–28.3)23.8 (20.3–28.4)25.2 (17.7–34.1)23.6 (17.0–31.2)0.807
Smoking history pack-years036 (15–80)46 (25–66)¶¶46 (30–65)++40 (20–60)¶¶<0.001
Smoking status ex-smoker/ current smokerNA5/43/412/5+15/0
FEV1 L2.5 (1.7–5.1)2.67 (1.8–3.5)2.8 (1.6–3.2)1.9 (1.1–2.9)0.6 (0.36–1.0)++,§§,ƒƒ,###<0.0001
FEV1/FVC %81.5 (66–121)76 (71–88)66.5 (65–70)61.5 (41–70)¶¶¶,+++32 (20–39)##,++,§§,§§§<0.0001
FEV1 % predicted108 (82–141)95 (75–120)86.66 (80–95)69 (43.2–77.8)¶¶,+++23.84 (15–28)##,++,§§,ƒƒ<0.0001
Inhaled β2-agonists
 Short-acting yes/no/unknown0/8/00/9/02/5/04/11/39/5/1§
 Long-acting yes/no/unknown0/8/00/9/01/6/02/13/36/8/1§
Inhaled anticholinergics
 Short-acting yes/no/unknown0/8/00/9/01/6/03/12/36/8/1§
 Long-acting yes/no/unknown0/8/00/9/00/7/02/13/310/4/1§
Inhaled short-acting β2-agonist plus anticholinergics yes/no/unknown0/8/00/9/00/7/01/14/33/11/1§
Corticosteroids
 Inhaled yes/no/unknown0/8/00/9/00/7/02/13/32/12/1§
 Oral yes/no/unknown0/8/00/9/00/7/00/15/32/12/1§
Inhaled long-acting β2-agonist plus corticosteroids yes/no/unknown0/8/00/9/00/7/02/13/39/4/2§
Mucolytics yes/no/unknown0/8/00/9/02/5/00/15/37/6/2§

Data are presented as median (range) or n. Statistical analysis was performed using Kruskal–Wallis nonparametric test followed by Dunn's multiple comparison post-test. Further patient descriptions, including inclusion and exclusion criteria are presented in the supplementary material. GOLD: Global Initiative for Chronic Obstructive Lung Disease; BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; NA: not applicable. #: two patients with GOLD stage III COPD (median (range) FEV1 44.5 (43.2–45.9)% predicted); : the mean age of the study group was 64 years; +: data missing from one patient; §: one patient with unknown medical history; ƒ: p<0.01 versus smokers without COPD; ##: p<0.05 versus patients with GOLD stage II–III COPD; ¶¶: p<0.005 versus never-smokers; ++: p<0.0001 versus never-smokers; §§: p<0.0001 versus smokers without COPD; ƒƒ: p<0.0005 versus patients with GOLD stage I COPD; ###: p<0.005 versus patients with GOLD stage II–III COPD; ¶¶¶: p<0.01 versus never-smokers; +++: p<0.05 versus smokers without COPD; §§§: p<0.02 versus patients with GOLD stage I COPD.