Development and Internal Validation of a Novel Pediatric-Adapted Liver (PAL) Score for Predicting Advanced Fibrosis: Comparison with Transient Elastography

Background & Aims: Accurate assessment of liver fibrosis is important for the management of pediatric chronic liver disease (CLD). Transient Elastography (TE) has emerged as a validated non-invasive method for accurately assessing hepatic fibrosis, yet it remains available only in specialized centers and requires specialized equipment. We aimed to develop and internally validate a novel, simple, blood-based scoring system—the pediatric-adapted liver score (PAL score)—to predict advanced fibrosis as defined by liver stiffness, measured using TE across diverse etiologies. Methods: A retrospective study was conducted on 107 pediatric patients with CLD who underwent liver stiffness measurement through TE. Advanced fibrosis was defined as a liver stiffness measurement corresponding to the F3 METAVIR stage or above. Independent predictors of advanced fibrosis were identified using multivariable logistic regression with manual backward elimination. To facilitate bedside utility, the regression model was simplified into a ratio-based index. Performance was assessed via the area under the receiver operating characteristic curve (AUROC) and validated using bootstrap resampling (10,000 iterations). Results: Gamma-glutamyl transferase (GGT), platelets, and albumin were identified as independent predictors of fibrosis. The simplified PAL score demonstrated good discrimination with an AUROC of 0.901 (95% CI: 0.84–0.95). While statistically equivalent to the adult-derived GGT-to-platelet ratio (GPR) and S-Index, the PAL score incorporates parameters of hepatic synthesis and portal hypertension that are absent from other ratios and is easier to calculate at the patient’s bedside. At a clinically practical integer cut-off of 5.0, the score achieved a sensitivity of 95.5% and a negative likelihood ratio of 0.06, effectively ruling out advanced fibrosis. Bootstrap validation confirmed the stability of the model (bootstrap-corrected AUC 0.901). Conclusions: The PAL score is the first simple fibrosis index derived for a diverse pediatric population. Highlighting its primary strength as a highly effective screening tool, the score achieves a sensitivity of 95.5% and a negative likelihood ratio of 0.06 at a user-friendly cut-off of 5. These robust metrics allow clinicians to confidently rule out advanced fibrosis, offering an accessible triage alternative in primary care settings where transient elastography is unavailable.