The Charlson and Elixhauser Scores Outperform the American Society of Anesthesiologists Score in Assessing 1-year Mortality Risk After Hip Fracture Surgery

Abstract

Background Risk adjustment has implications across orthopaedics, including informing clinical care, improving payment models, and enabling observational orthopaedic research. Although comorbidity indices (such as the American Society of Anesthesiologists [ASA] classification, Charlson comorbidity index [CCI], and Elixhauser comorbidity index [ECI]) have been examined extensively in the immediate perioperative period, there is a dearth of data on their three-way comparative effectiveness and long-term performance. Moreover, the discriminative ability of the CCI and ECI after orthopaedic surgery has not been validated in the ICD-10 era, despite new diagnosis codes from which they are calculated. Question/purpose Which comorbidity index (ASA, CCI, or ECI) is associated with the greatest accuracy on receiver operating curve (ROC) analysis with respect to the endpoint of death at 90 days and 1 year after hip fracture surgery in the ICD-10 era? Methods A retrospective study was conducted on all patients undergoing surgical fixation of primary hip fractures at two Level I trauma centers and three community hospitals from October 2016 to May 2019. This time frame allowed for a 1-year baseline period of ICD-10 data to assess comorbidities and at least a 1-year follow-up period to assess mortality. Initially 1516 patients were identified using Common Procedural Terminology and ICD codes, of whom 4% (60 of 1516) were excluded after manual review; namely, those with pathologic fractures (n = 38), periprosthetic fractures (n = 12), and age younger than 18 years (n = 10). Of the patients who were studied, 69% (998 of 1456) were women and the mean ± SD age was 77 ± 14 years; 45% (656 of 1456) were treated with intramedullary nails, 32% (464 of 1456) underwent hemiarthroplasties, 10% (149 of 1456) underwent THAs, 7% (104 of 1456) underwent percutaneous fixations, and 6% (83 of 1456) were treated with plates and screws. The mean ± SD ASA score was 2.8 ± 0.6, CCI was 3.1 ± 3.2, and ECI was 5.2 ± 3.5. Hip fracture fixation was chosen as the operation of interest given the high incidence of this injury, the well-documented effects of comorbidities on complications, and the critical importance of risk stratification and perioperative medical management for these patients. Demographics, comorbidities, surgical details, as well as 90-day and 1-year mortality were collected. Logistic regressions with ROC curves were used to determine the accuracy and comparative effectiveness of the three measures. The 90-day mortality rate was 7.4%, and the 1-year mortality rate was 15.0%. Results The accuracy (area under the curve [AUC]) for 1-year mortality was 0.685 (95% CI 0.656 to 0.714) for the ASA, 0.755 (95% CI 0.722 to 0.788) for the ECI, and 0.769 (95% CI 0.739 to 0.800) for the CCI. The CCI and ECI were more accurate than ASA (p < 0.001 for both), while the CCI and ECI did not differ (p = 0.30). The ECI (AUC 0.756 [95% CI 0.712 to 0.800]) was more accurate for 90-day mortality than the ASA (AUC 0.703 [95% CI 0.663 to 0.744]; p = 0.04), while CCI (AUC 0.742 [95% CI 0.698 to 0.785]) with ASA (p = 0.17) and CCI with ECI (p = 0.46) did not differ at 90 days. Conclusion Performance measures and research results may vary depending on what comorbidity index is used. We found that the CCI and ECI were more accurate than the ASA score for 1-year mortality after hip fracture surgery. Moreover, these data validate that the CCI and ECI can perform reliably in the ICD-10 era. If other studies from additional practice settings confirm these findings, as would be expected because of the objective nature of these indices, the CCI or ECI may be a useful preoperative measure for surgeons to assess 1-year mortality for hip fracture patients and should likely be used for institutional orthopaedic research involving outcomes 90 days and beyond. Level of Evidence Level III, diagnostic study.

Prognostic nomogram for risk of mortality after hip fracture surgery in geriatrics

“…According to the present multivariable Cox proportional hazards regression model, the CCI, but not the ASA score, was an independent factor associated with mortality. This is consistent with Varady et al [7] , which reported that CCI performed better than the ASA score for evaluating the 1-year mortality risk after hip fracture surgery, though some other studies have disagreed. Quach et al [13] found that the ASA score, rather than either version of the CCI, was independently associated with 12-month mortality.…”

“…Yet, as a single factor to predict the mortality risk of patients with hip fracture, the CCI did not perform well. Varady et al [7] reported an AUC value of 0.769 (95% CI 0.739-0.800) for CCI for predicting the 1year mortality risk. Karres et al [6] .…”

High Charlson Comorbidity Index Score is associated with early fracture-related complication for internal fixation of neck of femur fractures

“…The included patients were neck of femur fractures only, and we studied on fracture-related complications but not perioperative complications as current literature has shown that this risk is low with hip screws fixation 6 . Furthermore, studies have shown that the modified Elixhauser’s Comorbidity Measure achieves a very good prediction of complications following hip fractures and have been found to be superior to the Charlson Comorbidity Index 51 , although some studies have shown similar accuracies in terms of mortality risk 52 . We adopted ACCI as it has been published in numerous studies that the score correlates with mortality, complications, and readmission rates after treatment of hip fractures 22 , 33 , 53 – 55 , and has been used and published in our locality 56 .…”

A New Nomogram Model for Predicting 1-Year All-Cause Mortality After Hip Arthroplasty in Nonagenarians With Hip Fractures: A 20-Year Period Retrospective Cohort Study

“…Both aCCI and ASA classification are common tools for operative risk stratification. Previous studies have attempted to use CCI and ASA for risk stratification and suggested that CCI performed better than ASA classification in the prediction for 1-year mortality after surgery for hip fractures ( 17 , 18 ). However, some studies suggested that ASA classification was an independent risk factor for it, rather than CCI ( 19 ).…”