Predictive Value of the C-Reactive Protein to Albumin Ratio in 30-Day Mortality after Hip Fracture in Elderly Population: A Retrospective Observational Cohort Study.

Background: C-reactive protein (CRP) to Albumin ratio (CAR) has been used in multiple clinical settings to predict early mortality. However, there is a lack of evidence on the predictive role of CAR in 30-day mortality after a hip fracture. The purpose of this study was to establish a potential association between CAR and 30-day mortality and to assess if the CAR Receiving Operating Characteristics curve (ROC) can be a reliable predictor of early mortality.

Methods: We retrospectively reviewed the charts of 676 patients (>65 years) treated for hip fracture between 2006 and 2018. All hip fractures were included. Treatment strategies included closed reduction and internal fixation, open reduction and internal fixation, hemiarthroplasty, or total joint arthroplasty. Statistical analysis included T-test, Pearson correlation for CAR and other markers, ROC curves and area under the curve, Youden Model, and Odds Ratio.

Results: The 30-day mortality rate analysis showed that higher preoperative levels of CAR were associated with higher early mortality. When analyzing the area under the ROC curve (AUROC) for 30-day mortality, the reported value was 0.816. The point of the ROC curve corresponding to 14.72 was considered a cut-off with a specificity of 87% and a sensibility of 40.8%. When analyzing values higher than 14.72, the 30-day mortality rate was 17.9%, whilst, for values lower than 14.72, the 30-day mortality rate was 1.8%.

Conclusions: Patients older than 65 years affected by a hip fracture with increased preoperative levels of CAR are associated with higher 30-day mortality. Despite a moderate sensibility, considering the low cost and the predictivity of CAR, it should be considered a standard predictive marker.