Table 4. . Multivariate COX proportional hazard modeling.
HR, hazard ratio; CI, confidence interval; AIC, Akaike information criterion; LR, likelihood ratio test; PaO2/FiO2, partial pressure of oxygen in arterial blood to the fraction of inspired oxygen ratio; ROX, respiratory rate and oxygenation index; CRP, C-reactive protein; CT, computed tomography; SOFA, Sequential Organ Failure Assessment
| HR | 95% CI | P-value | AIC | LR | |
| Model 1: PaO2/FiO2 ratio | 181 | <0.001 | |||
| PaO2/FiO2 | 6.40 | 2.39, 17.1 | <0.001 | ||
| CRP at admission | 1.01 | 1.00, 1.01 | 0.004 | ||
| COVID-19 extension on chest CT | 1.03 | 1.01, 1.06 | 0.012 | ||
| SOFA score at 24 hours | 1.05 | 0.79, 1.39 | 0.755 | ||
| Model 2: ROX index | 183 | <0.001 | |||
| ROX index | 5.83 | 2.54, 13.4 | <0.001 | ||
| CRP at admission | 1.00 | 1.00, 1.01 | 0.035 | ||
| COVID-19 extension on chest CT | 1.03 | 1.00, 1.05 | 0.025 | ||
| SOFA score at 24 hours | 1.07 | 0.83, 1.38 | 0.597 | ||
| Model 3: modified ROX index | 178 | <0.001 | |||
| Modified ROX index | 8.24 | 3.16, 21.5 | <0.001 | ||
| CRP at admission | 1.01 | 1.00, 1.01 | 0.007 | ||
| COVID-19 extension on chest CT | 1.03 | 1.00, 1.05 | 0.027 | ||
| SOFA score at 24 hours | 1.11 | 0.85, 1.46 | 0.444 |