Frailty Index as a Risk Stratification Tool for the Proposed CMS Surgical Hip and Femur Fracture Treatment Bundle.

Objectives: To determine the extent to which the Comprehensive Geriatric Assessment based Frailty Index (FI) predicts in-hospital costs of care for older adult hip fracture patients with implications for risk adjustment of future bundled payment models by identifying higher-cost patients.

Design: Retrospective cohort study.

Setting: One academic level 1 trauma center in the United States of America.

Patient selection criteria: Included were all patients over the age of 65 who underwent surgery for a femoral neck or intertrochanteric hip fracture (OTA/AO 31A and 31B) between March 2018 and August 2020 and had a frailty index recorded for the injury admission.

Outcome measures and comparisons: The primary outcome of interest was a percentage difference of in-hospital total cost of care between severely frail, moderately frail, and non-frail patients. Univariate and multivariate regression were also used to evaluate the association of frailty index, along with other demographic and clinical variables, with cost of care.

Results: A total of 326 patients were included. Compared to non-frail patients, the average in-hospital cost was 20% higher for severely frail patients and 12% higher for moderately frail patients (both p<0.05). In univariate regression, FI was found to have a significant association with total cost (β=$1,106 incremental cost per 0.1 increase in FI, p=0.005) and direct cost (β=$586 incremental cost per 0.1 increase in FI, p=0.014).

Conclusion: Higher Frailty Index scores are associated with increased costs of in-hospital treatment for hip and femur fractures as both a categorical and continuous variable. Thus, Frailty Index offers a potential risk adjustment tool for future hip and femur fracture payment bundles.

Level of evidence: III.