211. Defining a surgical invasiveness threshold for major complications following adult spinal deformity surgery

Abstract

BACKGROUND CONTEXT Risk factors have been identified for complications following adult spinal deformity (ASD) surgery; however, the risk of complications following ASD surgery in relation to the degree of surgical invasiveness is unknown. Understanding the relationship between surgical invasiveness and risk of major complications is important to patients and surgeons for estimating these risks based upon the planned surgical treatment. PURPOSE To define a surgical invasiveness threshold that predicts increased likelihood of major complications following surgical treatment of ASD. STUDY DESIGN/SETTING Retrospective review of a prospective multicenter database PATIENT SAMPLE Five hundred seventy-four of 760 (76%) eligible ASD patients (>5 levels fused) were identified in a multicenter database with complete 2-year follow-up OUTCOME MEASURES Our primary outcome was development of a major complication at any time point in the postoperative period METHODS Surgical invasiveness was calculated according to the previously published and validated ASD Surgical and Radiographic (ASD-SR) score, which assigns point values to 13 operative and radiographic factors. Youden's index was used to identify the highest predicted probability cut-off of developing a major complication to be an ASD-SR of 90. Using this value, patients were divided into quartiles (Q1: ASD-SR 0-65; Q2: ASD-SR 66-89; Q3: ASD-SR 90-119; Q4: ASD-SR 120+). Odds of developing a major complication were analyzed after controlling for baseline frailty and radiographic deformity. RESULTS Mean age of patients was 59 ± 14 years, 79% females. Mean levels fused were 11.2 ± 4.3. The overall risk of a major complication was 17% in Q1, 21% in Q2, 35% in Q3 and 33% in Q4 (p 0.05). The mean ASD-SR scores above and below the ASD-SR threshold of 90 were 120.7 ± 25.4 and 63.4 ± 16.8, respectively. Example of a patient with an ASD-SR of 63 (low invasiveness): T11-Pelvis, 6 Smith-Peterson Osteotomies, -.9cm change in SVA, +1° change in TK, + 43° change in PT. Example of a patient with an ASD-SR of 121 (high invasiveness): T8-Pelvis, 3-column osteotomy, -2.3cm change in SVA, -5° change in TK, +38° change in PT. CONCLUSIONS ASD patients have an increased risk of major complications above an ASD-SR score of 90, while the risk of minor complications and inpatient medical complications is not significantly increased. The ASD-SR score can be used as a tool to counsel patients regarding these increased risks. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.