Table 2

Description* of the three chronic obstructive pulmonary disease (COPD) groups identified by cluster analysis

	All subjects n=342	Group 1 n=126	Group 2 n=125	Group 3 n=91	F^†
Cough day or night, %	49	62	38	44	8.19
Sputum day or night, %	53	63	46	51	4.05
Asthma (self-reported), %	9	11	8	9	0.22
Dyspnoea (modified Medical Research Council scale, 0–5), mean	2.6	3.2	1.9	2.8	33.53
St George Respiratory Questionnaire-Symptoms (0–100), mean	49	54	44	47	11.35
St George Respiratory Questionnaire-Activity (0–100), mean	47	61	32	49	60.01
St George Respiratory Questionnaire-Impacts (0–100), mean	27	36	17	26	42.62
Prebronchodilator forced expiratory volume in 1 s (FEV₁) (% predicted), mean	49	35	58	55	139.74
Postbronchodilator FEV₁ (% predicted), mean	52	38	63	58	148.99
Postbronchodilator FEV₁ to forced vital capacity ratio, mean	0.53	0.44	0.57	0.61	101.49
FEV₁ bronchodilation change (% of prebronchodilator FEV₁), mean	9.0	9.9	9.1	7.6	1.04
Thoracic gas volume (% predicted), mean	137	161	129	114	52.98
Inspiratory capacity/total lung capacity ratio, mean	0.31	0.23	0.34	0.37	95.26
Carbon monoxide diffusing capacity (% predicted), mean	65	54	73	70	13.67
Arterial oxygen partial pressure (mm Hg), mean	74	70	81	72	47.39
Time with arterial oxygen saturation <90% when sleeping (%), mean	19	26	6	27	23.88
Minimum arterial oxygen saturation during 6-minute walk test (%), mean	89	86	92	90	33.13
C-reactive protein in serum (mg/dl), mean	0.86	0.99	0.36	1.37	8.46
Fibrinogen in serum (g/l), mean	4.13	4.23	3.77	4.50	11.40
Tumour necrosis factor in serum (pg/ml), mean	0.87	0.88	0.72	1.05	1.37
Interleukin 6 in serum (pg/ml), mean	1.45	1.52	1.12	1.81	5.88
Peripheral blood neutrophil count (n×10⁹/l), mean	4.62	4.76	3.94	5.35	23.55
Skin prick test (number of positive allergens), mean	0.18	0.13	0.18	0.25	1.53
Body weight (kg), mean	76	69	74	90	87.04
Height (cm), mean	1.64	1.62	1.64	1.66	11.24
Body mass index (kg/m²), mean	28.2	26.0	27.2	32.4	78.30
Fat free mass index (kg/m²), mean	19.6	18.6	19.3	21.6	29.53
6-Minute walk total distance (m), mean	434	414	466	417	8.52
Myocardial infarction (doctor diagnosed), %	11	6	7	23	9.40
Congestive heart failure (doctor diagnosed), %	7	5	1	17	11.14
Left ventricle telediastolic diameter (mm), mean	50.5	49.6	50.1	52.3	5.34
Ejection fraction (%), mean	59.3	59.7	58.8	59.5	0.25
Tricuspid insufficiency, %	58	66	61	43	4.63
Diabetes (doctor diagnosed), %	19	16	14	32	6.11
Density less than −950 Hounsfield units in both lung infracarinal thin sections (%)^‡, mean	14	24	16	6	34.03
Bronchial wall thickness extension in right inferior lobe (score 0–3)^‡, mean	1.9	2.7	1.5	1.1	47.26
Potentially pathogenic microorganism colonisation^‡, %	34	36	35	26	0.79
Interleukin 8 (×10³) in sputum supernatant (pg/ml)^‡, mean	10.11	11.90	8.54	8.98	2.72
Neutrophil count in sputum (n×10⁶/ml)^‡, mean	370	250	290	570	1.59
Maximal oxygen uptake at cardiopulmonary incremental exercise test peak (% predicted)^‡, mean	62	53	69	68	19.93

↵* Non-standardised values of a selection of 40 out of 224 variables in figure 1, including those obtained with the variable selection procedure (bold text) and variables selected according to clinical experts' knowledge. Complete data are provided in Supplementary table 3.
↵† F values correspond to the ratio of the variance of the group means (between-group variance) over the overall variance of the variable (higher values meaning higher relevance of the variable for separating cluster groups), and were obtained by means of linear regression models using each variable as the outcome, and the cluster group as the exposure (see Supplement for details).
↵‡ Variables obtained in a subsample of patients (see text for details).