207. Cost benefit of implementation of risk stratification models for adult spinal deformity surgery

Abstract

<h3>BACKGROUND CONTEXT</h3> A previous study by Pellisé et al identified that a lowest instrumented vertebrae (LIV) at the pelvis, frailty, and sagittal deformity (global sagittal alignment [SVA], lordosis gap [PI-LL], T1 sagittal tilt [T1Slope]) were strong preoperative predictors of major complications. In addition to the preoperative predictors, blood loss and surgical time were strong predictors that occur operatively. It is unknown whether being at risk by these criteria has an effect on cost of surgery. <h3>PURPOSE</h3> To determine whether previously established risk stratification criteria will reduce operative costs. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study of a prospectively collected multicenter ASD database. <h3>PATIENT SAMPLE</h3> This study included 952 ASD patients. <h3>OUTCOME MEASURES</h3> Health-related quality of life measures (HRQLs), quality adjusted life years (QALYs), utility gained, ODI, total cost. <h3>METHODS</h3> Adult spinal deformity (ASD) patients with complete baseline (BL) and 2-year (2Y) HRQLs and radiographic data were included. Frailty score, sagittal deformity measures, blood loss, and surgical time were divided into tertiles, with the highest tertile being high risk. Published methods converted ODI to SF-6D. QALYs utilized a 3% discount rate for residual decline to life expectancy (LE, 78.7 years). Cost was calculated using the PearlDiver database and assessed for complications/major complications and comorbidities according to CMS.gov definitions. Cost per QALY at 2Y and LE were calculated for additive risk factors (LIV at pelvis, high frailty, any high sagittal deformity measure, high blood loss, high surgical time). These costs represented national averages of Medicare pay-scales for services within a 30-day window including length of stay and death differentiated by complication/comorbidity, revision, and surgical approach. Internal cost data were based on individual patient DRG codes. <h3>RESULTS</h3> Of 926 patients included, 118 did not meet any risk criteria, 171 met 1, 207 met 2, 151 met 3, 56 met 4, and 3 met 5 (these 3 patients were excluded due to small sample size). There was a significant trend (R2=0.897) in terms of national average cost at 2-years with increasing amount of risk measures met, as cost increased by $11,566 with each additional risk factor. Amount of risk factors met had a positive correlation to baseline ODI (0: 30.89; 1: 39.66; 2: 46.96; 3: 51.59; 4: 54.69; p<0.001) and 2Y ODI (0: 18.06; 1: 22.55; 2: 27.53; 3: 34.23; 4: 38.54; p<0.001). When analyzing initial surgical cost by DRG code, there was a $3,844 increase in cost per risk factor (R2=0.8703). Patients meeting 2 risk factors had the highest ODI improvement from BL to 2Y (p=0.06). QALYs gained at LE decreased by 0.0756 per risk factor (R2=0.8153). National average cost per QALY at 2Y increased by $45,852 per risk factor (R2=0.4151), and cost per QALY at LE increased by $15,759 per risk factor (R2=0.8822). <h3>CONCLUSIONS</h3> Increasing risk factors involving frailty, baseline deformity, and operative factors reduce cost effectiveness by increasing total cost and reducing QALYs. Preoperative or intraoperative measures to reduce a patient's amount of applicable risk factors would concurrently reduce operative cost and improve cost-effectiveness. Awareness of non-modifiable risk factors may also help educate surgical approach. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.