Associations between red blood cell distribution width (RDW), hemoglobin-to-RDW ratio (HRR), and mortality in hip fracture patients in the ICU: A MIMIC-IV database analysis

Hip fractures are associated with significant mortality, and hematologic indices such as red blood cell distribution width (RDW) and hemoglobin-to-RDW ratio (HRR) have shown potential as prognostic markers. However, their prognostic value in the intensive care unit (ICU) setting remains uncertain. This study aimed to explore the associations between RDW, HRR, and mortality in hip fracture patients requiring ICU admission. Data of patients with hip fractures admitted to the ICU were extracted from the MIMIC-IV database and retrospectively analyzed. The primary outcomes were 28-day and 1-year mortality. Associations between RDW, HRR, and mortality outcomes were evaluated using logistic regression and Cox proportional hazards models. A total of 488 patients were included. After adjustment, high RDW (≥ 14.3 %) was associated with significantly increased 28-day mortality (adjusted odds ratio [aOR] = 2.04, 95 % confidence interval [CI]: 1.07-3.88) and 1-year mortality (adjusted hazard ratio [aHR] = 1.95, 95 % CI: 1.15-3.29). High HRR (≥0.65 %) was independently associated with a reduced risk of 28-day mortality (aOR = 0.37, 95 % CI: 0.21-0.66) and 1-year mortality (aHR = 0.51, 95 % CI: 0.32-0.81) after adjusting for confounders. In conclusions, both RDW and HRR are independent predictors of mortality in patients with hip fractures admitted to the ICU. These indices could serve as a valuable prognostic tool in this patient population.