The Royal Free Hospital score: a calibrated prognostic model for patients with cirrhosis admitted to intensive care unit. Comparison with current models and CLIF-SOFA score

Abstract

Objectives: Prognosis for patients with cirrhosis admitted to intensive care unit (ICU) is poor. ICU prognostic models are more accurate than liver-specific models. We identified predictors of mortality, developed a novel prognostic score (Royal Free Hospital (RFH) score), and tested it against established prognostic models and the yet unvalidated Chronic Liver Failure-Sequential Organ Failure Assessment (CLIF-SOFA) model.

Methods: Predictors of mortality were defined by logistic regression in a cohort of 635 consecutive patients with cirrhosis admitted to ICU (1989-2012). The RFH score was derived using a 75% training and 25% validation set. Predictive accuracy and calibration were evaluated using area under the receiver operating characteristic (AUROC) and goodness-of-fit χ(2) for the RFH score, as well as for SOFA, Model for End-Stage Liver Disease (MELD), Acute Physiology and Chronic Health Evaluation (APACHE II), and Child-Pugh. CLIF-SOFA was applied to a recent subset (2005-2012) of patients.

Results: In-hospital mortality was 52.3%. Mortality improved over time but with a corresponding reduction in acuity of illness on admission. Predictors of mortality in training set, which constituted the RFH score, were the following: bilirubin, international normalized ratio, lactate, alveolar arterial partial pressure oxygen gradient, urea, while variceal bleeding as indication for admission conferred lesser risk. Classification accuracy was 73.4% in training and 76.7% in validation sample and did not change significantly across different eras of admission. The AUROC for the derived model was 0.83 and the goodness-of-fit χ(2) was 3.74 (P=0.88). AUROC for SOFA was 0.81, MELD was 0.79, APACHE II was 0.78, and Child-Pugh was 0.67. In 2005-2012 cohort, AUROC was: SOFA: 0.74, CLIF-SOFA: 0.75, and RFH: 0.78. Goodness-of-fit χ(2) was: SOFA: 6.21 (P=0.63), CLIF-SOFA: 9.18 (P=0.33), and RFH: 2.91 (P=0.94).

Conclusions: RFH score demonstrated good discriminative ability and calibration. Internal validation supports its generalizability. CLIF-SOFA did not perform better than RFH and the original SOFA. External validation of our model should be undertaken to confirm its clinical utility.

Figure 1

Receiver operating characteristic curve for the different prognostic models in the training and validation sample.

Figure 2

Performance of the Royal Free Hospital (RFH) score with the optimal cutoff point of −0.82 (validation sample).

Figure 3

Mortality according to number of failing organ system (FOS, according to SOFA and chronic liver failure-SOFA (CLIF-SOFA) criteria) and acute-on-chronic-liver-failure (ACLF) classification.