Association between red blood cell distribution width-hematocrit ratio and 28-Day all-cause mortality in patients with acute pancreatitis in ICU: A retrospective study

Acute pancreatitis (AP) is a sudden inflammatory condition of the pancreas that can lead to severe systemic complications and high mortality, especially in critically ill patients. Red cell distribution width-to-hematocrit ratio (RDH) has emerged as a potential prognostic biomarker in critical care. This study aimed to explore the association between RDH and 28-day mortality in intensive care unit (ICU) patients with AP. This retrospective observational cohort study utilized data from the Medical Information Mart for Intensive Care-IV (MIMIC-IV, v3.1) database. Cox proportional hazards regression and restricted cubic spline analyses were used to assess the relationship between RDH and 28-day all-cause mortality. Receiver operating characteristic curve analysis, along with area under the curve (AUC), net reclassification improvement, and integrated discrimination improvement, was performed to evaluate the incremental prognostic value of RDH beyond sequential organ failure assessment (SOFA) and SAPSⅡ scores. Survival curves and subgroup analyses were performed based on pertinent covariates. A total of 1126 ICU patients with AP were included. RDH were significantly associated with 28-day all-cause mortality. In multivariable Cox models, the highest RDH quartile exhibited a 5.52-fold increased mortality risk (heart rate: 6.52; 95% confidence intervals: 2.88-14.7; P <.05) compared to those in the lowest quartile. The relationship was linear (P for nonlinearity >.05). Kaplan-Meier survival curves demonstrated low survival rates in the highest RDH quartile (P <.001). RDH alone showed modest discrimination (AUC = 0.640), while SOFA (AUC = 0.724) and SAPSⅡ (AUC = 0.768) performed better. Adding RDH improved model performance (SOFA + RDH AUC = 0.743; SAPSⅡ+RDH AUC = 0.792) with significant net reclassification improvement and integrated discrimination improvement gains. RDH is an independent predictor of 28-day mortality in ICU patients with AP. Higher RDH values are linked with increased clinical severity and mortality risk.