The LIP score: a pathophysiology-driven tool for sepsis screening and prognosis—a multicenter prospective study

The development of convenient and effective screening tools for sepsis is a critical global priority, yet a systematically evaluated and efficient tool for early identification remains lacking. In this prospective, multicenter observational study across 10 tertiary hospitals in China, the novel LIP score (Lymphocyte count, INR, Procalcitonin) was validated against established tools. Analytical methods included ROC curve analysis for performance comparison, Restricted Cubic Splines (RCS) for ICU length of stay (ICU-LOS) association, and advanced visualizations (Sankey/Chord diagrams, SHAP) for risk stratification and feature interpretation. Among 1,202 enrolled adults with suspected infection, the LIP score demonstrated superior performance. For sepsis diagnosis (cutoff ≥ 3), its AUROC was 0.932 (95% CI: 0.916–0.945), with a sensitivity of 85.37% and a specificity of 94.83%, significantly outperforming all comparator scores (all P < 0.001). In mortality prediction, LIP surpassed SIRS ( P < 0.001) but was inferior to NEWS ( P = 0.031) and SOFA ( P < 0.001), while comparable to qSOFA ( P = 0.28). LIP scores showed a biphasic relationship with ICU stay and modestly predicted microbiological confirmation, on par with qSOFA, APACHE-II, and NEWS. As an early-warning tool, a threshold of LIP ≥ 2 provided high sensitivity (94.58%) but limited specificity (62.72%). Notably, applying a modified rule (any two of three components ≥ 1 point) increased the specificity to 83.14%. This multicenter study validates the LIP score as a simple and efficient screening tool for sepsis in hospitalized patients, demonstrating good diagnostic performance at a cutoff of ≥ 3 and close association with clinical outcomes; preliminary data also suggest promise for emergency use, though further validation is needed.