Lactate dehydrogenase and short-term mortality in ICU patients with ischemic stroke: a single-center retrospective analysis of MIMIC-IV.

BACKGROUND AND

aimsElevated lactate dehydrogenase (LDH) has been linked to unfavorable outcomes across various diseases, yet its prognostic relevance in critically ill patients with ischemic stroke (IS) remains insufficiently defined. This study aimed to investigate whether LDH levels at admission to the intensive care unit (ICU) are independently associated with short-term mortality among IS patients requiring critical care.

methodsThis retrospective cohort study utilized data from the Medical Information Mart for Intensive Care (MIMIC-IV, version 3.1) database. The primary and secondary endpoints were all-cause in-hospital mortality and 30 day mortality, respectively. Associations between LDH and outcomes were evaluated using Kaplan-Meier survival curves, multivariable Cox proportional hazards models, and restricted cubic splines (RCS) analyses. Discriminative performance was assessed by time-dependent receiver operating characteristic (ROC) curves and concordance index (C-index). Incremental prognostic value beyond established clinical scores (SAPS II, APS III, OASIS, and LODS) was quantified using category-free net reclassification improvement (NRI) and integrated discrimination improvement (IDI).

resultsOf 818 patients, higher LDH was associated with worse survival (log-rank P < 0.001). After full adjustment, LDH remained independently associated with in-hospital death (36.6% vs. 7.0%; HR 2.82, 95% CI 1.46-5.46; P = 0.002) and 30 day mortality (41.0% vs. 14.8%; HR 2.07, 95% CI 1.24-3.44; P = 0.005). However, results for 30 day mortality attenuate to non-significance after full adjustment in sensitivity analysis (41.0% vs. 14.8%; HR 1.45, 95% CI 0.97-2.17; P = 0.068). RCS modeling revealed a nonlinear relationship, with mortality risk rising sharply above approximately 268 IU/L. Log-transformed LDH demonstrated modest discriminative ability for both in-hospital (AUC 0.642, 95% CI 0.583-0.701; C-index = 0.657, 95% CI 0.612-0.702) and 30 day mortality (AUC 0.668, 95% CI 0.629-0.707; C-index = 0.652, 95% CI 0.617-0.687). Incorporating LDH into conventional severity scores modestly but significantly improved discrimination (positive NRI and IDI).

conclusionAdmission LDH levels are independently associated with in-hospital and 30 day mortality among critically ill IS patients and may serve as a potential adjunct to established prognostic tools for early risk stratification. External, multicenter validation is warranted to confirm these findings.