Table 3

Non-respiratory impairment/functional limitations and the prospective risk of COPD-related disability

Predictor variable*Prospective disability measure
Primary outcome†Secondary outcome†
Increase in proportion of activities unable to perform (n=1051)Development of ≥1 activity unable to perform in those with no baseline disability (n=777)
Non-respiratory impairment*
Body composition

  • 1.80 (1.08 to 3.02)

  • p=0.025

  • 1.42 (0.71 to 2.82)

  • p=0.32

Muscle strength
 Quadriceps

  • 1.93 (1.22 to 3.05)

  • p=0.0052

  • 1.83 (0.98 to 3.40)

  • p=0.057

 Hip flexors

  • 1.64 (1.03 to 2.59)

  • p=0.036

  • 1.83 (0.98 to 3.33)

  • p=0.052

 Hip abductors

  • 1.80 (1.15 to 2.84)

  • p=0.011

  • 2.22 (1.21 to 4.05)

  • p=0.01

 Elbow flexors

  • 1.51 (0.93 to 2.45)

  • p=0.093

  • 1.69 (0.89 to 3.20)

  • P=0.11

 Grip

  • 0.86 (0.51 to 1.47)

  • p=0.59

  • 0.57 (0.26 to 1.28)

  • p=0.18

 Pinch

  • 0.67 (0.39 to 1.15)

  • p=0.15

  • 0.64 (0.31 to 1.30)

  • p=0.22

Functional limitations*
Lower extremity functioning

  • 2.57 (1.65 to 4.01)

  • p<0.0001

  • 3.20 (1.76 to 5.81)

  • p<0.0001

Balance

  • 1.41 (0.90 to 2.21)

  • p=0.14

  • 2.18 (1.23 to 3.86)

  • p=0.008

Exercise performance

  • 2.93 (1.90 to 4.53)

  • p<0.0001

  • 4.01 (2.23 to 7.20)

  • p<0.0001

Mobility-related dyspnoea

  • 2.93 (1.80 to 4.75)

  • p<0.0001

  • 4.55 (2.22 to 9.30)

  • p<0.0001

Cognitive dysfunction

  • 1.34 (0.62 to 2.90)

  • p=0.46

  • 1.53 (0.51 to 4.57)

  • p=0.44

  • ↵* For each non-respiratory impairment/functional limitation, poor function was defined as the lowest quartile of the distribution (except cognitive impairment which used a standard cut-point of 24 points on the Mini-Mental Status Examination). Measurements = body composition (lean/fat ratio from bioelectrical impedance), muscle strength testing (dynamometry), lower extremity functioning (Short Physical Performance Battery), balance (Functional Reach Test), exercise performance (Six Minute Walk Test), and dyspnoea (Modified MRC Dyspnoea Scale).

  • ↵† Individual multivariable logistic regression analyses controlling for age, sex, race, height, educational attainment, household income, smoking status, and respiratory impairment (FEV1 and oxygen saturation). All results are ORs (95% CIs) with accompanying p values.