TABLE 1

Characteristics of 370 chronic obstructive pulmonary disease (COPD) patients according to whether they experienced oxygen desaturation during the 6 min walk test (6MWT)

TotalNo desaturationDesaturationp-value#
Subjects37028486
Sex0.83
 Female147 (40)76.2%23.8%
 Male223 (60)77.1%22.9%
Age years63±6.863.1±6.964.0±6.60.31
Body composition0.08
 Normal215 (58)80.5%19.5%
 Cachectic98 (27)74.5%25.5%
 Obese57 (15)66.7%33.3%
Smoking habits<0.001
 Ex-smoker205 (55)69.8%30.2%
 Daily smoker165 (45)85.5%14.5%
GOLD (2007) stage<0.001
 II180 (49)91.7%8.3%
 III160 (43)66.9%33.1%
 IV30 (8)40.0%60.0%
Exacerbations in past 12 months0.18
 0–1300 (82)78.1%21.9%
 ≥266 (18)70.0%30.0%
PaO2 at baseline kPa9.3±1.19.5±1.18.6±0.9<0.001
Charlson comorbidity score0.15
 1220 (59)76.4%23.6%
 284 (23)71.4%28.6%
 3–666 (18)84.8%15.2%
Pre-6MWT SpO294±2.695±2.493±2.7<0.001
Post-6MWT SpO291±5.694±2.783±5.5<0.001
Pre-6MWT pulse86±1584±14.590±14.6<0.01
Post-6MWT pulse110±18107±16.5118±1.6<0.001
Post-6MWT pulse/age-expected  maximal pulse ratio0.7±0.10.68±0.10.76±0.1<0.001
6MWD m432±103.5440.7±98.8406.0±114.7<0.01
  • Data are presented as n, n (%) or mean±sd, unless otherwise stated. GOLD: Global Initiative for Chronic Obstructive Lung Disease; PaO2: arterial oxygen tension; SpO2: arterial oxygen saturation measured by pulse oximetry. #: Chi-squared for categorical variables and t-test for continuous variables.