Table 1—

Characteristics of the patient groups

ControlStage IIStage IV
Subjects n8118
Age yrs63 (36–78)68 (44–81)54 (44–61)
Smoking (C/Ex/N)3/3/26/5/00/8/0
Pack-yrs smoking27 (0–75)40 (14–58)31 (12–54)
FEV1 % pred104 (83–134)68 (50–76)#21 (13–29)#
FEV1/FVC %74 (70–81)53 (37–68)#35 (24–66)#
Chronic bronchitisNoNoNo
  • Data are presented as mean (range), unless otherwise stated. Stage II: Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II chronic obstructive pulmonary disease (COPD); Stage IV: GOLD stage IV COPD; C: current smoker; Ex: ex-smoker, not smoking for ≥1 yr; N: never-smoker; FEV1: forced expiratory volume in one second; % pred: percentage of predicted value; FVC: forced vital capacity. #: indicates a significant difference compared with the control group.