Common Comorbidities and a Comparison of 4 Comorbidity Indices in Patients Undergoing Orthopaedic Oncology Surgery
Authors: Patel Shalin S. , Nalty Theresa , Fletcher Douglas H. , Ballard Timothy S. , Frink Spencer J. , Bird Justin E. , Lewis Valerae O. 
Published: January 2025

Background:
Comorbidity indices are used to help to estimate patients’ length of hospital stay, care costs, outcomes, and mortality. Increasingly, they are considered in reimbursement models. The applicability of comorbidity indices to patients undergoing orthopaedic oncology surgery has not been studied. The purpose of this study was to determine the predominant comorbidities in patients undergoing orthopaedic oncology surgery and to evaluate the predictive value of these indices.

Methods:
Patient demographic characteristics, diagnoses, and preoperative comorbidities were collected retrospectively on 300 patients undergoing orthopaedic oncology surgery between January 2014 and March 2023. In this study, 3 subsets of 100 patients each with malignant primary bone tumors, malignant primary soft-tissue tumors, or osseous metastatic disease were randomly selected. Comorbidities were tabulated and weighted according to the guidelines of the Charlson Comorbidity Index (CCI), the National Institute on Aging/National Cancer Institute (NIA/NCI) index, the van Walraven Index, and the Agency for Healthcare Research and Quality (AHRQ) Index. Two-tailed bivariate Pearson correlations were performed to assess the relationship between the indices and between each index and patient outcomes. Comorbidities in our patient population were compared with those published in other studies.

Results:
The predominant comorbidities in patients undergoing orthopaedic oncology surgery were hypertension, deficiency anemias, metastatic disease, recent unintended weight loss or being underweight, and fluid or electrolyte disorders. The percentage of patients with certain comorbidities exceeded those reported in other cancer, orthopaedic, and inpatient populations. The 4 comorbidity indices had variable correlation when assessing our patient population. The number of comorbidities and the weighted scores from all indices demonstrated little to no correlation with length of stay and survival in our patient sample.

Conclusions:
The prevalence of many comorbidities in patients undergoing orthopaedic oncology surgery is greater than those reported in other patient populations. Commonly utilized indices demonstrate variable correlation with one another. With these tools, there was little to no correlation between comorbidities and patient outcomes in our patient population. The comorbidities deemed protective in these tools may underestimate the true assessment of the comorbidities in patients undergoing orthopaedic oncology surgery. This highlights the importance of developing tools to properly assess the comorbidities in defined patient populations, especially as these models are used to set benchmarks for measuring patient outcomes; assessing quality, efficiency, and safety; and determining reimbursement criteria.

Level of Evidence:
Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.