Relative contribution of respiratory impairment and non-respiratory impairment/functional limitations to prospective risk of COPD-related disability
| COPD severity measure | Area under the receiver operating characteristic curve (95% CI) | |
| Entire cohort (n=1051) | GOLD Stage II or greater | |
| Model 1: sociodemographic and personal characteristics | 0.65 (0.59 to 0.70) | 0.66 (0.60 to 0.72) |
| Model 2: sociodemographic characteristics + respiratory impairment | 0.69 (0.63 to 0.74) | 0.70 (0.65 to 0.76) |
| Model 3: sociodemographic characteristics + respiratory impairment + non-respiratory impairment/functional limitations | 0.75 (0.70 to 0.80) | 0.78 (0.72 to 0.84) |
| Overall comparison | p<0.001 | p<0.001 |
| Comparison of model 2 vs model 1 | p=0.029 | p=0.064 |
| Comparison of model 3 vs model 2 | p=0.003 | p=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).