Red Cell Distribution Width as an Independent Predictor of Long-Term Mortality in Hip Fracture Patients: A Prospective Cohort Study

Red blood cell distribution width (RDW) has been found to be a significant prognostic factor of mortality in many cardiovascular diseases. However, a link between RDW at admission with long-term mortality in the hip fracture population has not been well established. Therefore, we sought to evaluate the long-term prognostic value of RDW in a well-defined hip fracture cohort, and to compare the effect of RDW in patients with and without anemia. A prospective cohort study was performed on 1479 hip fracture patients admitted at the General Hospital of Chinese PLA between January 2000 and October 2011 with a follow-up study over a 2-year period. A total of 1479 patients were used for the evaluation of 2-year all-cause mortality, while 804 patients with more than 4 years of follow-up were extracted for further evaluation of 4-year all-cause mortality. Cox proportional regression was used to evaluate the association between admission RDW and long-term mortality, adjusting for potential confounding variables. Higher RDW values were strongly associated with increased all-cause mortality. After adjusting for age, mean corpuscular volume, admission hemoglobin, comorbidities, and complications, RDW had a significant independent association with both 2-year mortality with a hazard ratio (HR) of 1.183 (95% confidence interval [CI], 1.017 to 1.376) and 4-year mortality with an HR of 1.244 (95% CI, 1.052 to 1.471). In stratified analysis, the effect of RDW was even more pronounced, with 2-year mortality HR of 1.341 (95% CI, 1.095 to 1.643) and 4-year mortality HR of 1.345 (95% CI, 1.071 to 1.688) in non-anemic patients. In non-anemic patients, elevated RDW values are significantly associated with increased odds of all-cause mortality, implying that RDW may be a possible laboratory biomarker for risk stratification in non-anemic hip fracture patients. Further studies are needed to confirm the current finding in different and larger hip fracture cohorts.