Supplementary Material for: Hemoglobin-to-Red Cell Distribution Width Ratio at Admission as an Anemia-Independent Predictor of Mortality after Fragility Hip Fracture Surgery in Older Adults

Background: The hemoglobin-to-red cell distribution width ratio (HRR), which has demonstrated better predictive ability than the red blood cell distribution width (RDW) and hemoglobin (Hb) level, has not been used to predict orthopedic surgical outcomes and may be a novel prognostic parameter for mortality.
Methods: In this single-center cohort study, data of 363 patients (aged ≥60 years) who underwent surgery for fragility hip fracture at our institution between January 2016 and December 2018 were retrospectively analyzed. Multivariable Cox proportional hazards and Kaplan–Meier survival curve analyses were performed to compare the high and low HRR and RDW groups, divided based on cutoff values. The power of mortality prediction over time was assessed by comparing Harrell’s concordance index using the bootstrapping method.
Results: Among 363 patients, the overall mortality was 48.48% (176/363), with a mean±standard deviation of 4.31±2.09 (0.02–7.44) years. HRR was significantly associated with all-cause mortality after hip fracture surgery (hazard ratio: 0.989; 95% confidence interval: 0.978–0.999; p=0.044). Moreover, during the follow-up period after 1 year, HRR demonstrated the second-highest predictive ability for mortality among all laboratory parameters and indicators reflecting general condition, and it remained unaffected by anemia status for up to 4 years.
Conclusions: HRR is proposed as a novel prognostic indicator for mid- to long-term survival after hip fracture surgery in older patients.