Discriminative Ability for Adverse Outcomes After Surgical Management of Hip Fractures: A Comparison of the Charlson Comorbidity Index, Elixhauser Comorbidity Measure, and Modified Frailty Index

Objectives: The Charlson comorbidity index (CCI), Elixhauser comorbidity measure (ECM), and modified frailty index (mFI) have been associated with mortality after hip fracture. The present study compares the clinically informative discriminative ability of CCI, ECM, and mFI, as well as demographic characteristics for predicting in-hospital adverse outcomes after surgical management of hip fractures. Methods: Patients undergoing hip fracture surgery were selected from the 2013 National Inpatient Sample. The discriminative ability of CCI, ECM, and mFI, as well as demographic factors for adverse outcomes were assessed using the area under the curve analysis from receiver operating characteristic curves. Outcomes included the occurrence of any adverse event, death, severe adverse events, minor adverse events, and extended hospital stay. Results: In total, 49,738 patients were included (mean age: 82 years). In comparison with CCI and mFI, ECM had the significantly largest discriminative ability for the occurrence of all outcomes. Among demographic factors, age had the sole or shared the significantly largest discriminative ability for all adverse outcomes except extended hospital stay. The best performing comorbidity index (ECM) outperformed the best performing demographic factor (age) for all outcomes. Conclusion: Among both comorbidity indices and demographic factors, the ECM had the best overall discriminative ability for adverse outcomes after surgical management of hip fractures. The use of this index in correctly identifying patients at risk for postoperative complications may help set appropriate patient expectations, assist in optimizing prophylaxis regimens for medical management, and adjust reimbursements. More widespread use of this measure for hip fracture studies may be appropriately considered. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.