Hospital Frailty Risk Score and healthcare resource utilization after surgery for metastatic spinal column tumors
Authors: Elsamadicy Aladine A. , Koo Andrew B. , Reeves Benjamin C. , Pennington Zach , Yu James , Goodwin C. Rory , Kolb Luis , Laurans Maxwell , Lo Sheng-Fu Larry , Shin John H. , Sciubba Daniel M. 
Published: February 2022

OBJECTIVE
The Hospital Frailty Risk Score (HFRS) was developed utilizing ICD-10 diagnostic codes to identify frailty and predict adverse outcomes in large national databases. While other studies have examined frailty in spine oncology, the HFRS has not been assessed in this patient population. The aim of this study was to examine the association of HFRS-defined frailty with complication rates, length of stay (LOS), total cost of hospital admission, and discharge disposition in patients undergoing spine surgery for metastatic spinal column tumors.

METHODS
A retrospective cohort study was performed using the years 2016 to 2019 of the National Inpatient Sample (NIS) database. All adult patients (≥ 18 years old) undergoing surgical intervention for metastatic spinal column tumors were identified using the ICD-10-CM diagnostic codes and Procedural Coding System. Patients were categorized into the following three cohorts based on their HFRS: low frailty (HFRS < 5), intermediate frailty (HFRS 5–15), and high frailty (HFRS > 15). Patient demographics, comorbidities, treatment modality, perioperative complications, LOS, discharge disposition, and total cost of hospital admission were assessed. A multivariate logistic regression analysis was used to identify independent predictors of prolonged LOS, nonroutine discharge, and increased cost.

RESULTS
Of the 11,480 patients identified, 7085 (61.7%) were found to have low frailty, 4160 (36.2%) had intermediate frailty, and 235 (2.0%) had high frailty according to HFRS criteria. On average, age increased along with progressively worsening frailty scores (p ≤ 0.001). The proportion of patients in each cohort who experienced ≥ 1 postoperative complication significantly increased along with increasing frailty (low frailty: 29.2%; intermediate frailty: 53.8%; high frailty: 76.6%; p < 0.001). In addition, the mean LOS (low frailty: 7.9 ± 5.0 days; intermediate frailty: 14.4 ± 13.4 days; high frailty: 24.1 ± 18.6 days; p < 0.001), rate of nonroutine discharge (low frailty: 40.4%; intermediate frailty: 60.6%; high frailty: 70.2%; p < 0.001), and mean total cost of hospital admission (low frailty: $48,603 ± $29,979; intermediate frailty: $65,271 ± $43,110; high frailty: $96,116 ± $60,815; p < 0.001) each increased along with progressing frailty. On multivariate regression analysis, intermediate and high frailty were each found to be significant predictors of both prolonged LOS (intermediate: OR 3.75 [95% CI 2.96–4.75], p < 0.001; high: OR 7.33 [95% CI 3.47–15.51]; p < 0.001) and nonroutine discharge (intermediate: OR 2.05 [95% CI 1.68–2.51], p < 0.001; high: OR 5.06 [95% CI 1.93–13.30], p = 0.001).

CONCLUSIONS
This study is the first to use the HFRS to assess the impact of frailty on perioperative outcomes in patients with metastatic bony spinal tumors. Among patients with metastatic bony spinal tumors, frailty assessed using the HFRS was associated with longer hospitalizations, more nonroutine discharges, and higher total hospital costs.