Table 2.
Linear regression analysis for LOS (log-transformed). The univariate models include CCI or Clavien-Dindo as the only covariate. The multivariate models are adjusted for the following covariates: type of surgery (major vs. minor), open vs. laparoscopy, age (per year), American Society of Anesthesiologists (ASA) score (1–2 vs. 3–4), Child grade (A vs. B), duration of surgery (>4 h vs. ≤4 h), center volume (high vs. medium/low). Patients died during hospital stay are excluded from all samples.
| Sample | Model | Derivation Set | Validation Set | |||
|---|---|---|---|---|---|---|
| Mean Change (95% CI) | R2 | RMSE | R2 | RMSE | ||
| Overall sample Derivation set n = 1331. Validation set n = 1304. |
CCI, per 10 unit increase Univariate model |
0.290 (0.273;0.307) | 45% | 0.41 | 36% | 0.49 |
| Clavien-Dindo, per category increase Univariate model |
0.312 (0.292;0.332) | 41% | 0.43 | 34% | 0.49 | |
| CCI, per 10 unit increase Multivariate model |
0.267 (0.251;0.282) | 57% | 0.37 | 44% | 0.50 | |
| Clavien-Dindo, per category increase Multivariate model |
0.291 (0.273;0.309) | 54% | 0.38 | 43% | 0.51 | |
| Subgroup of patients with at least two complications Derivation set n = 177. Validation set n = 154. |
CCI, per 10 unit increase Univariate model |
0.240 (0.197;0.283) | 41% | 0.47 | 15% | 0.59 |
| Clavien-Dindo, per category increase Univariate model |
0.254 (0.186;0.323) | 24% | 0.54 | 12% | 0.59 | |
| CCI, per 10 unit increase Multivariate model |
0.219 (0.176;0.262) | 47% | 0.45 | 23% | 0.59 | |
| Clavien-Dindo, per category increase Multivariate model |
0.223 (0.157;0.289) | 32% | 0.52 | 21% | 0.63 | |
LOS: Length of stay; CCI: Comprehensive complication index; CI: Confidence Interval; RMSE: Root mean squared error.