The risk analysis index as a predictor of 30-day mortality for elderly obese patients undergoing elective total joint arthroplasty

Introduction

The older population of the United States of America is continuing to increase, leading to rising rates of degenerative joint disease. Combined with the high prevalence of obesity in the US, orthopaedic surgeons are performing record numbers of elective total joint arthroplasty (TJA) procedures in higher risk patients. As age and obesity are risk factors for mortality following TJA, preoperative risk stratification tools such as frailty may be used to optimize surgical candidate selection to mitigate adverse outcomes.

Methods

The American College of Surgeons National Surgical Quality Improvement Program database was queried for patients ≥65 years of age with a BMI of ≥30 kg/m² who underwent elective primary total knee or total hip arthroplasty for degenerative joint disease. Frailty was measured using the 5-item Modified Frailty Index (mFI-5) and the Risk Analysis Index (RAI). Multivariate regression was performed to evaluate predictive value of frailty and discriminatory accuracy was quantified using receiver operating characteristic (ROC) analysis.

Results

There were 169,065 patients who met the inclusion criteria from 2015 to 2019. The median age was 71 years, 60.8 % were women and 72.6 % were White. Increasing frailty predicted greater mortality as measured by the RAI and mFI-5. Further, the RAI had superior discrimination compared to the mFI-5 when quantified using ROC analysis.

Discussion

Frailty as measured by the RAI has superior clinical applicability, predictive value and discrimination for identifying patients at risk of mortality following TJA in an older obese population. Given this, orthopaedic surgeons may use the RAI as a tool for optimizing candidate selection and identifying high risk patients preoperatively.