Univariate Cox regression analyses comparing the Gender, Age, Physiology (GAP) index staging system with scores derived from two separate hazard ratio formulae
| Composite score (max score 3) | Hazard ratio (95% CI) | p-value | Harrell's c-index |
| Univariate analysis | |||
| GAP index staging system | 2.00 (1.61–2.48) | <0.0001 | 0.62 |
| CALIPER–CPI | 2.23 (1.85–2.69) | <0.0001 | 0.67 |
| CALIPER only | 2.14 (1.78–2.58) | <0.0001 | 0.67 |
| Bivariate analysis | |||
| GAP index staging system | 1.25 (0.97–1.62) | 0.09 | |
| CALIPER–CPI | 1.99 (1.58–2.50) | <0.0001 | |
| GAP index staging system# | (-0.03–0.48) | 0.09 | |
| CALIPER–CPI# | (0.46–0.95) | 0.001 | |
| GAP index staging system | 1.41 (1.11–1.80) | 0.005 | |
| CALIPER only | 1.87 (1.51–2.30) | <0.0001 | |
| GAP index staging system# | (0.10–0.59) | 0.007 | |
| CALIPER only# | (0.41–0.86) | 0.001 |
CALIPER–CPI: derived from the hazard ratios of the three independent predictors of mortality in a combined visual, CALIPER and pulmonary function index multivariate model. CALIPER only: derived from the hazard ratios of CALIPER variables that were independent predictors of mortality. Bivariate analyses compared the hazard ratio derived scores to the GAP index staging system with the results confirmed on bootstrapping of 1000 samples. CPI: composite physiologic index. #: bootstrapped results.