162. Predictors of a sustained clinical benefit following adult spinal deformity correction with a minimum 3-year follow-up

Abstract

<h3>BACKGROUND CONTEXT</h3> Despite multiple reports showing favorable long-term functional outcomes following adult spinal deformity (ASD) correction, it is still unclear which patient factors may impact the sustainability of these outcomes. <h3>PURPOSE</h3> To assess the sustainability of functional gains following ASD correction and determine predictors for postoperative loss of patient functionality. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> A total of 689 ASD patients. <h3>OUTCOME MEASURES</h3> Sustained clinical benefit, Oswestry Disability Index (ODI), reoperation, mechanical failure, proximal junctional failure (PJF) <h3>METHODS</h3> ASD patients with baseline (BL) and three-year (3Y) follow-up data were considered for analysis. Only patients who met the definition of sustained clinical benefit (SCB) at one-year (1Y) were included: 1)Passias et al's threshold for ODI (ODI<31.3), 2) did not develop PJF, and 3) did not have a reoperation for a mechanical failure. Patient groups were created by those who met SCB at 3Y, and those who did not. SCB outcomes were also reported at five-years (5Y) postoperatively. Means comparison tests assessed differences in patient groups. Factors predicting SCB were identified using adjusted regression and conditional inference tree (CIT) analysis. <h3>RESULTS</h3> A total of 157 patients met inclusion criteria and had SCB at 1Y. Patient breakdown for SCB was 75.0% at 3Y. Gender (78% vs 81%), BMI (25.5 vs 26.4), levels fused (10.6 vs 10.5), operative time (345 vs 362 min), and surgical invasiveness were similar between groups, all P>.05. Following surgery, patient groups were similarly aligned to Lafage et al's age-adjusted PT, PI-LL, and SVA, all P>.05. Regression and CIT analysis adjusting for BL deformity determined that patients who met SCB at 3Y were 95.4% less likely to have an ASD-mFI score > 11 (.046[.005-.420], p=0.006), 73.1% less likely to be older than 55 years at DOS (.269[.091-.798], p=.018), 69.4% less likely to have a CCI score > 0(.306[.116-.811], p=.017), and 86.9% less likely to have a BL EQ5D score < .723 (.131[.029-.585], p=.008). Adjusted for patients without follow-up, sustained clinical benefit at 5Y was 57.9%. Predictors of SCB from 3Y to 5Y included age, CCI and EQ5D, all P < .05. <h3>CONCLUSIONS</h3> Sustained clinical benefit was maintainable for 75.0% of the operative ASD cohort at 3Y. Similarly, a 57.9% maintenance rate of sustained clinical benefit at 5Y reflects the longevity of ASD correction. Independent predictors of sustained clinical benefit included age, frailty, comorbidities and the patient health state. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.