Prognostic value of the FBG/HDL-C ratio for 28-day all-cause mortality in critically ill patients: a retrospective cohort study with external validation.

Abstract

Background: Metabolic dysregulation in critical illness may involve early changes in early morning fasting blood glucose (FBG) and high-density lipoprotein cholesterol (HDL-C), but the prognostic value of combining these measures is unclear.

Methods: We analyzed adult ICU patients from MIMIC-IV (v3.1) with FBG (03:00-07:59) and HDL-C measured within 24 h of admission. Using multivariable Cox models, we assessed the association between the FBG/HDL-C ratio and 28-day all-cause mortality, examining nonlinear effects via restricted cubic splines and exploratory mediation by white blood cell count (WBC) and blood-urea-nitrogen (BUN). Findings were externally validated in the eICU database.

Results: Elevated FBG/HDL-C ratios were independently associated with 28-day all-cause mortality, with a nonlinear threshold identified at 5.934 and an AUC of 0.773. This association may be partially mediated by systemic inflammation and renal impairment.

Conclusions: Among critically ill patients with available FBG and HDL-C measurements, the FBG/HDL-C ratio was independently associated with short-term mortality, suggesting its potential as a supplementary risk stratification tool-though generalizability is limited by nonroutine HDL-C testing.