Table 4

Relative contribution of respiratory impairment and non-respiratory impairment/functional limitations to prospective risk of COPD-related disability

COPD severity measureArea under the receiver operating characteristic curve (95% CI)
Entire cohort (n=1051)GOLD Stage II or greater
Model 1: sociodemographic and personal characteristics0.65 (0.59 to 0.70)0.66 (0.60 to 0.72)
Model 2: sociodemographic characteristics + respiratory impairment0.69 (0.63 to 0.74)0.70 (0.65 to 0.76)
Model 3: sociodemographic characteristics + respiratory impairment + non-respiratory impairment/functional limitations0.75 (0.70 to 0.80)0.78 (0.72 to 0.84)
 Overall comparisonp<0.001p<0.001
 Comparison of model 2 vs model 1p=0.029p=0.064
 Comparison of model 3 vs model 2p=0.003p=0.0017
  • Area under the ROC curve derived from three multivariable logistic regression models using primary disability outcome. Baseline model included age, sex, race, height, educational attainment, household income, and smoking history. Second model included all baseline factors plus respiratory impairment indicators (FEV1 and baseline resting oxygen saturation). Third model includes all previous variables plus non-respiratory impairment (muscle strength, body composition) and functional limitations (lower extremity function, balance, submaximal exercise performance, mobility-related dyspnoea, and cognitive impairment).