Table 2.
Hazard Ratios for Mortality of Random Survival Forest-Selected Variables Used in MLMP-COPD (Cox Regression) Model Trained on Subjects in COPDGene
| Feature | Unadjusted Hazard Ratio (95% CI) | P Value | Adjusted Hazard Ratio (95% CI) | P Value |
|---|---|---|---|---|
| 6-Min walk distance, per 100 ft | 0.85 (0.83-0.87) | < .0001 | 0.9 (0.87-0.93) | < .0001 |
| FEV1 % predicted | 0.96 (0.957-0.968) | < .0001 | 0.99 (0.974-0.997) | .01 |
| Age | 1.04 (1.03-1.05) | < .0001 | 1.04 (1.03-1.06) | < .0001 |
| mMRC dyspnea score | 1.49 (1.39-1.61) | < .0001 | 1.15 (1.05-1.25) | .002 |
| FEV1/FVC ratioa | 0.009 (0.005-0.02) | < .0001 | 0.1 (0.02-0.45) | .003 |
| FEF25%-75%, L/min | 0.14 (0.1-0.2) | < .0001 | 1.74 (1.02-2.98) | .04 |
| Resting SaO2 | 0.9 (0.88-0.92) | < .0001 | 0.97 (0.948-0.995) | .02 |
| Exacerbations per year | 1.2 (1.14-1.28) | < .0001 | 1.03 (0.96-1.11) | .4 |
| Pack-years cigarette smoking | 1.01 (1.006-1.011) | < .0001 | 1.01 (1.002-1.008) | .0003 |
| BMI, kg/m2 | 0.97 (0.96-0.99) | .00022 | 0.97 (0.95-0.99) | .001 |
| Severe exacerbations | 1.95 (1.6-2.4) | < .0001 | 1.33 (1.05-1.7) | .02 |
| PA:A ratio | 5.8 (3.01-11.3) | < .0001 | 2.7 (1.35-5.55) | .005 |
| Pi10 | 5.5 (3.1-9.7) | < .0001 | 1.6 (0.8-3.3) | .2 |
| Diabetes | 1.4 (1.1-1.8) | .0072 | 1.3 (1.01-1.73) | .04 |
| % LAA < −950 HU | 1.03 (1.027-1.04) | < .0001 | 0.995 (0.98-1.004) | .3 |
Adjusted models include all covariates, and FVC and GOLD spirometry grade were removed for multicollinearity. FEF25%-75% = forced expiratory flow 25% to 75%; MLMP = machine learning mortality prediction; mMRC = modified Medical Research Council; PA:A = pulmonary artery to aorta; % LAA < −950 HU = percent emphysema determined by the percent low attenuation area of the lungs < −950 Hounsfield units; Pi10 = square root of wall area of a hypothetical airway with internal perimeter of 10 mm; SaO2 = arterial oxygen saturation. See Table 1 legend for expansion of other abbreviations.
FEV1/FVC is reported as a ratio from 0 to 1 and not as a percentage.