Prognostic value of baseline RDW-CV in critically ill patients with pelvic fractures: A retrospective cohort study.

Abstract

Red blood cell distribution width coefficient of variation (RDW-CV) is a potential prognostic biomarker, but its prognostic significance in critically ill patients with pelvic fractures remains unclear. This study evaluated the association between baseline RDW-CV and mortality and developed a nomogram for predicting 365-day mortality. This retrospective cohort study included adult patients with pelvic fractures admitted to the intensive care unit (ICU) in the MIMIC-IV database. Baseline RDW-CV was defined as the first measurement after ICU admission. Associations with 30-, 90-, and 365-day mortality were evaluated using Kaplan-Meier analysis, Cox regression, restricted cubic splines (RCS), and subgroup analyses. A nomogram incorporating RDW-CV, age, and Acute Physiology Score III (APSIII) was internally validated. Among 270 patients, 37 (13.7%) had elevated RDW-CV (>15.5%). Patients with elevated RDW-CV had higher 30-day (32.4% vs. 7.3%), 90-day (35.1% vs. 9.4%), and 365-day mortality (40.5% vs. 12.0%) than those with RDW-CV ≤ 15.5% (all P < 0.001), with significantly lower survival probabilities (log-rank P < 0.0001). In fully adjusted Cox models, elevated RDW-CV remained independently associated with 30-day (HR 2.68, 95% CI 1.20-5.99; P = 0.016), 90-day (HR 2.33, 95% CI 1.12-4.84; P = 0.024), and 365-day mortality (HR 2.21, 95% CI 1.14-4.26; P = 0.018). RCS analysis showed a significant overall association with 365-day mortality (P = 0.007), without significant nonlinearity (P = 0.079). Findings were consistent across prespecified subgroup and sensitivity analyses. The nomogram showed good calibration and discrimination for 365-day mortality (AUC 0.878). Exploratory analyses of dynamic RDW-CV changes during ICU stay showed no significant association with survival. Elevated baseline RDW-CV was independently associated with increased short- and long-term mortality in critically ill patients with pelvic fractures. Baseline RDW-CV may provide a practical marker for early risk stratification, while serial RDW-CV measurements offered limited additional prognostic value.