Demographics and baseline characteristics

Mild (GOLD 1)Moderate (GOLD 2)SmokersNever-smokers
Subjects n659784397262449335
Age years67.2±10.165.9±9.60.01968.0±9.8§,f65.9±10.3f65.6±9.4§66.3±9.80.008
Male404 (61.3)412 (52.6)<0.001259 (65.2)145 (55.3)262 (58.4)150 (44.8)<0.001
Never-smokers190 (28.8)335 (42.7)<0.001132 (33.2)§58 (22.1)§0335 (100.0)<0.001
Former smokers352 (53.4)346 (44.1)<0.001212 (53.4)§140 (53.4)f346 (77.1)§,f0<0.001
Current smokers117 (17.8)103 (13.1)0.01553 (13.4)§,f64 (24.4)f103 (22.9)§0<0.001
GOLD1397 (60.2)0397 (100.0)000
GOLD2262 (39.8)00262 (100.0)00
Self-reported physician-diagnosed asthma202 (30.7)124 (15.8)<0.00193 (23.4)§109 (41.6)§,f76 (16.9)f48 (14.3)§<0.001
Any respiratory medication prescription+215 (32.6)85 (10.8)<0.00181 (20.4)§,f134 (51.1)§,f54 (12.0)f31 (9.3)§<0.001
Emphysema score1.8±3.10.5±1.3<0.0011.4±2.5§2.3±3.7§0.7±1.5§0.2±0.7§<0.001
RV/TLC %42±9.637.5±8.2<0.00139.2±8.7f46.3±9.4§,f37.4±8.0f37.6±8.5§<0.001
Chronic bronchitis112 (17.0)99 (12.6)0.001944 (11.1)¶¶68 (26.0)f,##,¶¶69 (15.4)##30 (9.0)f<0.001

Data are presented as n, mean±sd or n (%), unless otherwise stated. BMI: body mass index; COPD: chronic obstructive pulmonary disease; GOLD: Global Initiative for Chronic Obstructive Lung Disease; ICS: inhaled corticosteroids; LABA: long-acting β2-agonist; LAMA: long-acting muscarinic antagonist; RV/TLC: residual volume/total lung capacity; SABA: short-acting β2-agonist; SAMA: short-acting muscarinic antagonist. #: p-values were obtained by performing Chi-squared or Fisher's exact test for category variables, and t-test (normal distribution) or Mann–Whitney U tests (non-normal distribution) for continuous variables. : p-values were obtained by performing Chi-squared or Fisher's exact tests for category variables, and analysis of variance (normal distribution) or Kruskal–Wallis test (not normal distribution) for continuous variables. +: Respiratory medicines included were: SAMA/SABA; LABA±SAMA/SABA; LAMA±SAMA/SABA; LAMA+LABA±SAMA/SABA; ICS±SAMA/SABA; LABA+ICS±SAMA/SABA; LAMA+ICS±SAMA/SABA; LAMA+LABA+ICS±SAMA/SABA. §, f, ##, ¶¶: Values with the same symbol are significantly different from each other after Tukey adjustment for multiple comparisons (p<0.05). Bold indicates statistical significance.