Table 2.
Univariable and Multivariable Marginal Cox Models With Robust Standard Errors to Assess the Prognostic Effect of the MPI Score at Admission for In-Hospital Mortality
| Models* | MPI Groups | HR (95% CI) | for MPI Groups | p Value | Survival C-Statistic (95% CI)† | HL p Value‡ | Diff. Survival C-Statistic p Value | cNRI (95% CI)† | cNRI for Events | cNRI for Nonevents | p Value CNRI | IDI (95% CI)† |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Model 1 | — | — | — | 0.500 | — | <.001 | — | — | — | — | — |
| Model 1 + MPI (at admission) | Intermediate vs. Low | 3.10 (0.92–10.50) | .069 | 0.777 (0.715–0.839) | .589 | 0.792 (0.514–1.086) | 0.425 | 0.367 | <.001 | 0.043 (0.032–0.060) | |
| High vs. Low | 6.79 (2.11–21.88) | .001 | |||||||||
| Model 2 | — | — | — | 0.568 (0.456–0.682) | .290 | <.001 | — | — | — | — | — |
| Model 2 + MPI (at admission) | Intermediate vs. Low | 3.09 (0.90–10.53) | .072 | 0.783 (0.720–0.845) | .656 | 0.931 (0.669–1.165) | 0.604 | 0.326 | <.001 | 0.045 (0.034–0.063) | |
| High vs. Low | 6.67 (2.06–21.66) | .002 | |||||||||
| Model 3 | — | — | — | 0.703 (0.625–0.782) | .257 | <.001 | — | — | — | — | — |
| Model 3 + MPI (at admission) | Intermediate vs. Low | 3.48 (1.02–11.88) | .047 | 0.849 (0.791–0.906) | .845 | 0.999 (0.757–1.204) | 0.661 | 0.337 | <.001 | 0.084 (0.061–0.119) | |
| High vs. Low | 8.31 (2.54–27.19) | <.001 |
Notes: cNRI = continuous net reclassification index; HR = hazard ratio; IDI = Integrated Discrimination Improvement; MPI = Multidimensional Prognostic Index.
*Model 1: unadjusted; Model 2: age, sex adjusted; Model 3: age, sex, and diseases (heart failure, arrhythmia, pneumonia, COPD, respiratory failure, dementia, acute or chronic kidney failure) adjusted.
†Discrimination and reclassification measures for in-hospital mortality risk prediction, adding the MPI at admission variable into the reference model (ie, Model 1–2–3), within a time horizon equal to the median length of stay of 9 days.
‡ p Value from Hosmer–Lemeshow (HL) test for calibration.