A U shaped association between the HCT-ALB and hospital mortality in patients with sepsis

Abstract

The difference between hematocrit and serum albumin (HCT-ALB) demonstrates diagnostic significance in infectious diseases, yet the nonlinear relationship between HCT-ALB and hospital mortality in ICU patients with sepsis remains unexplored. This retrospective multicenter cohort study analyzed 7,546 ICU sepsis patients (mean age 66 ± 16 years) to elucidate the HCT-ALB-mortality relationship. Using Cox proportional hazards models with smooth curve fitting, we identified a U-shaped association: Threshold analysis revealed an inflection point at 6.1. Below this threshold, each unit HCT-ALB increase corresponded to reduced mortality risk (adjusted HR 0.986, 95%CI 0.972-0.999; P = 0.036). Conversely, values ≥ 6.1 predicted escalating risk (adjusted HR 1.048 per unit increase, 95%CI 1.037-1.060; P < 0.0001). Significant age interaction was observed (P for interaction < 0.05), with heightened mortality risk in elderly patients (≥ 65 years: HR 1.022, 95%CI 1.014-1.031). These findings establish HCT-ALB as a non-linear predictor of sepsis outcomes, emphasizing its critical threshold dynamics and age-dependent prognostic implications.

Keywords: HCT-ALB; Mortality; Sepsis; U-shaped association; eICU.

Fig. 1

Flow chart of the study population.

Fig. 2

Smoothing spline fitting curve. Associations between the HCT-ALB and Hospital Mortality in ICU patients with sepsis. A threshold, nonlinear association between HCT-ALB and Hospital Mortality was found in a Cox proportional hazards regression model. The solid red line represents the smooth curve fit between variables. Blue bands represent the 95% confidence interval from the fit. All adjusted for Age; Sex; BMI; SOFA Score; Ventilation; Dialysis; Site of Infection; Temperature; Heart Rate; Mean BP; WBC; Vasopressor Use, AIDS; Metastatic Cancer; Diabetes; CHF; AMI; Pneumonia; Arrhythmia.