Oxidative Medicine and Cellular Longevity

Research Article

Heterogeneity of Systemic Oxidative Stress Profiles in COPD: A Potential Role of Gender

Table 4

Clinical, functional, and muscle characteristics in clusters of COPD patients.


	Cluster 1	Cluster 2	Cluster 3	Cluster 4	interact.

Sex ratio (W/M)	8/11	5/14	8/2	6/0	<0.01

Age (years)	59 ± 7	63 ± 7	61 ± 8	57 ± 4	0.23
BMI (kg/m²)	24.0 ± 4.8	25.3 ± 2.8	25.4 ± 4.4	24.1 ± 4.8	0.71
Fat-free mass index (kg/m²)	17.4 ± 2.4	17.9 ± 2.2	16.6 ± 2.3	15.5 ± 1.7	0.14
Muscle mass index (kg/m²)	8.0 ± 1.6	8.5 ± 1.4	7.0 ± 1.5^#	6.6 ± 0.6^#	0.02
FEV₁ (% pred.)	58 ± 24	50 ± 20	51 ± 13	61 ± 26	0.74
BODE score [18]	2.1 ± 1.3	1.6 ± 1.6	3.0 ± 1.4	1.8 ± 1.5	0.29
Breathlessness, MRC score	1.5 ± 1.3	1.5 ± 1.0	1.5 ± 1.3	1.3 ± 0.8	0.97
Tobacco consumption (packs/years)	43 ± 21	46 ± 26	34 ± 20	56 ± 27	0.31
Physical activity level, Voorips score [21]	4.6 ± 3.1	5.3 ± 4.1	4.1 ± 2.7	2.5 ± 1.1	0.69
6-MWD (m)	557 ± 87	516 ± 104	469 ± 35	481 ± 67	0.07
6-MWD (% pred.)	85 ± 14	79 ± 16	77 ± 10	79 ± 13	0.40
(% pred.)	53 ± 19	46 ± 16	49 ± 21	57 ± 24	0.53
VO₂sl (% pred.)	62 ± 17	57 ± 16	64 ± 17	63 ± 19	0.68
QMVC (Nm)	98 ± 29	119 ± 45	90 ± 33	77 ± 16	0.11
QMVC (% pred.)	73 ± 14	81 ± 24	71 ± 16	68 ± 14	0.53
Qend (s)	397 ± 170	327 ± 105	337 ± 92	458 ± 253	0.70

Results are expressed in mean ± SD. versus cluster 1; versus cluster 2. COPD = chronic obstructive pulmonary disease; W = women/M = men; MRC = Medical Research Council; BODE index = body mass index, airway obstruction, dyspnoea, and exercise capacity index (6-MWD); BMI = body mass index (kg/m²); FEV₁ (% pred.) = forced expiratory volume in 1 second; W_sl (% pred.) = symptom-limited power output; VO₂sl (% pred.) = symptom-limited oxygen uptake; 6-MWD (m) = 6-minute walking distance; QMVC (Nm) = quadriceps maximal voluntary contraction expressed in Newtons; Qend (s) = quadriceps endurance time expressed in seconds.