168 Sustenance of Substantial Clinical Benefit in Adult Spinal Deformity Corrective Surgery Patients: A Minimum 5-Year Outcomes Analysis

Abstract

INTRODUCTION: Clinical outcomes for adult spinal deformity patients has been extensively reported on, however factors associated with sustaining two year (2Y) substantial clinical benefit (SCB) till five year (5Y) remains unclear. METHODS: ASD patients fused from at least L1 to sacrum with 5Y postoperative data were included. Good Outcome(GO) was defined as: no reoperation, mechanical failure, proximal junctional failure(PJF) based on Lafage criteria, and [meeting either: (1) SCB for Oswestry Disability Index(ODI)(decrease of >18.8), or (2) ODI <15 and Scoliosis Research Society(SRS-22r) Total>4.5]. Multivariable analysis controlled for age, BMI, CCI, frailty, deformity, HRQLs, and surgical variations. RESULTS: 330 ASD patients were included. 42% achieved GO at 2Y(2+) while 47% at 5Y(5+) did. 71% of 2+ cohort attained 5+. In 2- cohort, 29% achieved 5+. Isolating 2+ cohort, assessing 5+ vs 5-: 5- had greater SVA deformity at 5Y (p < .05). Regaining the level of activity postoperatively was associated with 4x higher odds of maintaining GO from 2Y to 5Y (p < .05). The odds of achieving GO at 5Y in 2+ decreased by 47% for each additional comorbidity and decreased by 74% in those that had lower extremity paresthesias at BL (both p < .05). Decreased number of levels fused, decreased correction in SVA and increased correction in PI-LL to be predictive of sustaining 2Y GO till 5Y (all p < 0.05). CONCLUSIONS: Overall, 47% had substantial clinical benefit till 5Y. While 71% of patients at 2Y sustained good clinical outcome till 5Y, major contributors to its loss were adjacent segment changes and rod fracture. The odds of achieving SCB till 5Y decreased by nearly 50% for each additional comorbidity. Decreased levels fused along with decreased correction of SVA and increased correction in PI-LL were predictive of optimal sustaining of clinical outcomes.