Association Between Allostatic Load and Delirium in ICU Patients: A Retrospective Analysis of the MIMIC-IV Database

Background: Allostatic load reflects the cumulative physiological effects of chronic and repeated stress on the body and is associated with dysregulation of multiple systems. This study aimed to examine the association between the allostatic load score (ALS) and the development of delirium in intensive care unit (ICU) patients. Method: The adult patients from the Medical Information Mart for Intensive Care (MIMIC-IV) database were screened and included in this study. Allostatic load was scored by hemoglobin A1c, high-density lipoprotein, total cholesterol, systolic blood pressure, diastolic blood pressure, body mass index, C-reactive protein, and serum albumin, and varied from 0 to 8. Restricted cubic spline and multivariate logistic regression were used to assess the relationship between ALS and delirium risk in the ICU. The threshold of the ALS was determined by the decision tree approach. A sensitivity analysis was also conducted. Results: A total of 656 patients were included in the study, and the incidence of delirium was 50.6% (n = 332). In a fully adjusted restricted cubic spline model, an increase in ALS was linearly positively correlated with the occurrence of delirium in the ICU (p-overall = 0.039, p-nonlinear = 0.506). The threshold for ALS was determined to be 3. ALS ≥ 3 was associated with increased delirium rates (p < 0.001), longer hospital stays (p < 0.001), and higher in-hospital mortality (p = 0.002). Subgroup analyses revealed no significant interactions (all p values for interactions > 0.05). Conclusions: Higher ALS was linearly associated with increased risk of ICU delirium. An ALS ≥ 3 identified patients with greater delirium incidence, longer hospital stays, and higher mortality.