Table 1– Baseline characteristics and disease progression in both study groups

Variable	Younger COPD	Older COPD	p-value
Subjects n	103	463
Baseline characteristics
Age years	50±4	72±5
Males	85	92	0.02
Follow up months	62 (43–98)	50 (36–69)	<0.001
Survival	90	65	<0.001
Active smoker	59	20	<0.001
FEV₁ % predicted	53±24	48±20	0.06
GOLD 1	17.4	7.6	0.002
GOLD 2	28.2	35.2	0.17
GOLD 3	37.9	41.0	0.55
GOLD 4	16.5	16.2	0.94
Assessments	4 (3–6)	4 (3–5)	0.01
Charlson index	2.3±1.5	5.0±2.5	<0.001
BODE index	3.4±2	4.1±2	0.049
Quartile 1	31	28	0.55
Quartile 2	39	30	0.13
Quartile 3	20	25	0.32
Quartile 4	10	17	0.14
Annual change
FEV₁ mL·year⁻¹	−38.8±93	−40.6±96	0.86
FEV₁ % predicted	−0.75±3	−0.66±3.8	0.80
BODE index	0.19±0.5	0.23±0.6	0.42
Rapid decliners^#	42	46	0.41

Data are presented as mean±sd, % or median (interquartile range), unless otherwise stated. COPD: chronic obstructive pulmonary disease; FEV₁: forced expiratory volume in 1 s; GOLD: Global Initiative for Chronic Obstructive Lung Disease; BODE: body mass index, airflow obstruction, dyspnoea, exercise capacity. ^#: FEV₁ decline >40 mL·year⁻¹.