Table 1.

Characteristics of Patients with COPD Stratified by Six Minute Walking Distance (6MWD)

Characteristics	6MWD < 350m	6MWD> 350m	p-value
N	17	38
Age (y), mean	64 (59 – 69)	62 (59 – 65)	0.42
Sex (F)	10	15	0.19
BMI (kg/m2)	30.3 (28.1 – 32.5)	27.8 (25.8 – 29.8)	0.12
Smoking history, pack years, mean	58 (44 – 72)	53 (41 – 64)	0.54
Smoking status (Current smoker) (n)	7	17	0.81
CAD (n)	0	3	NS‡
Congestive Heart Failure (n)	0	1	NS
Diabetes Mellitus (n)	6	1	<0.01
FEV1 (L), mean	0.96 (0.71 – 1.21)	1.42 (1.22 – 1.62)	<0.01
FEV1 (% predicted), mean	34 (26 – 42)	46 (41 – 52)	0.01
FEV1/FVC, mean	54 (46 – 61)	57 (51 – 63)	0.49
RV, L, mean	3.9 (3.2 – 4.7)	3.8 (3.4 – 4.2)	0.8
FRC, L, mean	4.5 (3.7 – 5.2)	4.8 (4.3 – 5.2)	0.51
TLC, L, mean	6.5 (5.9 – 7.2)	7.2 (6.6 – 7.8)	0.2
DLCO, uncorrected (ml/min/mmHg), mean	10.27 (7.88 – 12.65)	13.83 (12.33 – 15.33)	0.01
DLCO, % predicted, mean	48 (39 – 57)	61 (56 – 66)	<0.01
VO2 max, % predicted, mean	54 (46 – 61)	63 (57– 69)	0.08
VE/MVV %, mean	71 (65 – 78)	69 (62 – 77)	0.74
HRR %, mean	46 (34 – 58)	69 (62 – 76)	<0.01
Pre-SPO2 %, mean	92 (89 – 95)	95 (94 – 96)	<0.01
Peak-SPO2 %, mean	90 (87 – 93)	94 (93 – 95)	<0.01

^*Numbers in brackets denote 95% confidence intervals. 6MWD denotes the six minute walking distance. FEV1 denotes the forced expiratory volume in 1 second, FVC the forced vital capacity, RV the residual volume, FRC the functional residual capacity, TLC the total lung capacity, DLCO the diffusing capacity of the lung for carbon monoxide.

^**VO2 max is the peak oxygen uptake. VE/MVV is the maximum minute ventilation during exercise relative to minimum voluntary ventilation at rest; a ratio > 80% suggests a pulmonary limitation to exercise. O2 pulse approximates stroke volume. HRR is the heart rate recovery and SpO2 denotes arterial oxygen saturation.

^†n, number of cases

^‡NS, non-significant