Association between the hemoglobin, albumin, lymphocyte, and platelet (HALP) score and 28-day mortality in neurocritical care patients: a retrospective cohort study based on the MIMIC-IV database.

BACKGROUND: In recent years, reliable prognostic markers are increasingly important in neurocritical care. The hemoglobin, albumin, lymphocyte, and platelet (HALP) score, a composite biomarker reflecting systemic immune-nutritional status, has shown promise as a predictor. This study aims to evaluate the prognostic value of the HALP score for predicting 28-day mortality in neurocritical care unit (NCCU) patients. MATERIALS AND METHODS: We conducted a retrospective cohort study by identifying neurocritical care patients from the MIMIC-IV database. The association between the HALP score and 28-day mortality was primarily assessed using multivariable Cox proportional hazards regression. Multiple analytical approaches were employed to comprehensively examine this relationship, including restricted cubic spline (RCS) regression to evaluate nonlinearity and Kaplan-Meier survival analysis. A risk prediction nomogram was developed based on a Cox regression model. The model's discriminative performance at 28 days was evaluated using receiver operating characteristic (ROC) curve analysis, with the area under the curve (AUC) quantified using logistic regression. RESULT: Finally, 858 patients in the MIMIC database were analyzed, with 28-day ICU and in-hospital mortality rates of 21.0% and 20.4%, respectively. In the fully adjusted Cox model for ICU mortality, notably, the continuous HALP score was not independently predictive (HR = 0.99, 95% CI 0.98-1.00, p = 0.13). However, when analyzed categorically, which may better capture nonlinear risk relationships, higher HALP categories showed significant associations. Specifically, the 28-day ICU mortality rates progressively decreased across low, moderate, and high HALP score groups (29.7% vs 20.3% vs 12.9%, respectively; p < 0.001). After adjusting for all covariates using Cox regression, high HALP scores demonstrated significantly lower mortality risk compared to the lowest scores (HR = 0.56, 95% CI 0.36-0.87; p = 0.009). Restricted cubic spline analysis revealed a nonlinear threshold effect of the HALP score on mortality risk. The HALP score provided incremental predictive risk value for 28-day mortality when combined with conventional critical illness severity scores. The predictive model based on the HALP score achieved area under the curve (AUC) values of 0.71, 0.72, and 0.73 in the complete, Internal Validation Subset A, and Internal Validation Subset B, respectively. Our risk model provided additional identification of neurocritical patients when combined with traditional ICU scoring systems. This performance profile suggests that the HALP score may hold complementary predictive value to traditional ICU scoring systems. CONCLUSION: Our findings are consistent with an inverse association between HALP scores and short-term survival in neurocritical care patients. With a modest predictive discrimination (AUC ≤ 0.73), this scoring system may have potential as a complementary clinical risk assessment tool. Future validation is warranted to confirm its utility in aiding the risk stratification of neurocritical care patients.