Who are super-utilizers in adult spine deformity surgery and how can surgeons identify them preoperatively?

BACKGROUND CONTEXT: A relatively small percentage of patients are responsible for a disproportional amount of resource utilization in adult ASD surgery and contribute to significantly elevating the average cost across the surgically treated patients. These patients are called super-utilizers (SU). Modest reduction in the frequency of these super-utilization episodes has the potential to significantly improve the value of ASD surgery. PURPOSE: The goal of this study was to determine which, if any, baseline patient, radiographic, and/or surgical factors are the most important drivers of this disproportional increased resource utilization. We hypothesize that baseline patient factors predicts super-utilizers (SU) in adult spinal deformity surgery (ASD) more than surgical or deformity factors. STUDY DESIGN/SETTING: Retrospective Review of a prospective, multicenter registry. PATIENT SAMPLE: A total of 1299 index operative ASD patients eligible for 2-yr follow-up. OUTCOME MEASURES: Predictors of SU vs Non-SU in ASD. METHODS: A prospective multicenter consecutive series of ASD patients was reviewed. Inclusion criteria was diagnosis of ASD (scoliosis≥20°, C7-SVA≥5cm, PT≥25°, or TK≥60°), >4 level posterior fusion, and minimum 2-year follow-up. Index and total episode of care (EOC) cost in 2022 dollars were calculated using average itemized direct costs obtained from the administrative hospital records for all events in the inpatient EOC. Patients with total 2-year EOC cost greater than 90^th percentile were considered SU. Multivariate generalized linear models were used to identify the most significant predictors of SU. RESULTS: A total of 1299 patients were eligible for 2-yr follow-up with mean age 60.0+14.1 years, 76% female, and 93% caucasians. SU patients are marginally older (+2.6 yrs; p=0.03), depressed (34.2% vs 25.8%; p=0.03) and tend to have higher propensity for fraility (p=0.003), comorbidities (0.01), reoperation rates (54.8% vs 17.0%; p<0.001), and LOS (+3 days; p<0.0001) compared to non-SU. While degree of sagittal deformity (Schwab sagittal modifiers, all p>0.05) and proportion of 3-column osteotomies (p>0.05) were similar between the groups, SU patients have higher surgical invasiveness score (+28; p<0.001), more vertebrae fused (+3; p<0.0001); more interbody fusions (80% vs 55%; p<0.0001), more BMP use (87.3% vs 69.4%; p=0.0002); longer OR time (+91 mins; p<0.0001), increased blood loss (+700 mL; p<0.0001), and longer length of stay (+3 days; p<0.0001). Index and EOC cost were 49% (p<0.0001) and 62% (p<0.0001) higher respectively in SU. While cost/QALY was 3-times higher in SU compared to non-SU. Multivariate analysis identified Schwab modifier SVA, surgical invasiveness, OR time, blood loss, BMP use, and LOS as strong predictors of SU (all p<0.01). CONCLUSIONS: Surgical invasiveness score greater than 118, being in OR for more than 7.6 hrs, blood loss more than 700 ml, utilizing BMP, and LOS more than 11 days were strong predictors of being a SU. Patients with SVA grade of + and ++ were less likely to be a SU compared to SVA grade 0. Procedural and resource utilization factors were strong predictors of being a SU compared to patient factors. FDA Device/Drug Status: This abstract does not discuss or include any applicable devices or drugs.