Table 1

Baseline demographics

VariableOverall (n=729)Neither (n=194)Muscle (n=137)Cardiovascular (n=154)Both (n=132)
Age (years)67 (8)66 (7)*** 63 (8)*** 70 (7)*** 70 (7)***
Gender (% male)60.658.354.767.562.9
Smoking history (total pack years)47 (28)45 (27)47 (26)51 (31)47 (28)
BMI (kg / m2)27.3 (5.8)26.3 (4.9)** 26.9 (5.6)27.1 (4.9)28.3 (6.5)*
Fat-free mass (kg)51.0 (11.1)49.7 (10.6)50.1 (11.2)51.9 (10.5)52.2 (11.9)
CAT score (0–40)20 (0–40)17 (0–38)*** 22 (1–39)** 19 (3–40)21.5 (6–40)*
SGRQ total score51.4 (22.3)44.2 (21.2)*** 57.4 (21.5)*** 47.7 (22.5)*55.8 (20.5)*
FEV1 (L)1.34 (0.53)1.50 (0.52)*** 1.31 (0.53)1.32 (0.50)1.26 (0.50)
FEV1 (% predicted)52.2 (16.1)57.4 (14.2)*** 49.4 (16.3)*51.8 (16.4)50.5 (15.8)
FEV1/FVC0.48 (0.13)0.49 (0.12)0.48 (0.13)0.47 (0.12)0.49 (0.13)
Muscle indices
 QMVC (kg)30.6 (11.5)36.1 (10.1)23.4 (7.9)36.7 (10.7)22.7 (8.2)
 QMVC (% predicted)68.2 (20.7)81.4 (15.3)51.5 (12.0)82.2 (14.9)50.2 (12.9)
 SPPB total score10 (1–12)11 (3–12)*** 10 (3–12)11 (4–12)** 9 (2–12)***
 6MWD (m)345 (130)404 (104)*** 338 (129)361 (125)282 (132)***
Cardiovascular indices
 Supine MAP (mm Hg)98 (12)96 (11)*95 (10)*** 100 (10)*100 (11)*
 aPWV (m/s)10.3 (2.6)8.3 (1.1)8.3 (1.1)12.2 (2.0)12.7 (1.9)
Inflammatory markers
 Fibrinogen (g/dL)3.49 (0.86)3.44 (0.95)3.41 (0.76)3.49 (0.78)3.52 (0.90)
 hsCRP (mg/L)6.57 (12.1)7.45 (19.7)6.11 (8.13)5.63 (6.95)6.365 (6.55)
 WCC (×109/L)7.50 (2.16)7.32 (2.15)7.19 (2.18)7.42 (1.95)7.70 (2.38)
Comorbidities
 Exacerbations per year1.9 (2.1)1.71 (1.8)2.2 (2.0)*1.81 (2.34)2.2 (2.3)*
 Diabetes (%)11.46.37.210.418.3**
 Antihypertensive therapy (%)35.931.428.939.043.9*
 Cholesterol-lowering therapy (%)32.622.828.537.9** 43.8***
 Previous myocardial infarction (%)7.96.36.69.19.2
  • Baseline demographics for overall cohort (n=729) and phenotypic groups. Values expressed as mean (SD) for continuous variables and median (range) for discrete variables. The ‘Neither’ group (n=194) represents subjects with neither elevated aPWV nor skeletal muscle weakness. The ‘Muscle’ group (n=137) represents subjects with skeletal muscle weakness alone. The ‘Cardiovascular’ group (n=154) represents subjects with cardiovascular manifestation, defined as elevated aPWV, alone, and the ‘Both’ group (n=132) contains subjects demonstrating both skeletal muscle weakness and elevated aPWV. Skeletal muscle weakness according to predicted QMVC based on equations developed by Seymour et al 2 and elevated aPWV defined as >10 m/s.

  • *P<0.05, **P<0.01, ***P<0.001 for significant differences across groups. For continuous variables, the P value represents differences between overall mean and group mean. For ordinal and binary variables, the P value represents differences between the ‘Neither’ group and the remaining groups. Adjustments have not been made for multiple comparisons.

  • 6MWD, 6 min walk distance; aPWV, aortic pulse wave velocity; BMI, body mass index; CAT, COPD Assessment Test; hsCRP, high-sensitivity C reactive protein; MAP, mean arterial pressure; QMVC, quadriceps maximal volitional contraction; SGRQ, St George’s Respiratory Questionnaire; SPPB, short physical performance battery; WCC, white cell count.