Friday, September 28, 2018 3:00 PM–4:00 PM abstracts: spinal deformity analysis: 220. Predicting extended operative time and length of inpatient stay in cervical deformity corrective surgery

Abstract

BACKGROUND CONTEXT As the field of cervical deformity (CD) surgery has continued to progress, it is increasingly common for surgeons to operate on more challenging cases and higher risk patients, resulting in longer operative time and inpatient length of stay (LOS). The factors predicting extended operative time and LOS for CD patients have been understudied. PURPOSE Identify predictors of extended operative time and LOS after CD-corrective surgery using a statistical learning algorithm. STUDY DESIGN/SETTING Retrospective review of prospective, multicenter CD database. PATIENT SAMPLE A total of 142 surgical CD patients. OUTCOME MEASURES Operative time, LOS, health-related quality of life (HRQL) scores. METHODS Cervical deformity patients (C2–C7 Cobb>10°, CL>10°, cSVA>4cm, or CBVA>25°)>18 years with baseline (BL) radiographic data. Patients were stratified: extended LOS (E-LOS; >75th percentile) and normal LOS (N-LOS; 12 hours. Univariate tests assessed differences in BL patient and surgical metrics between LOS groups and extended op time. Conditional Inference Decision Trees identified factors contributing to extended LOS and op time, and cut-offs at which factors have a global effect. A Conditional Variable Importance Table used a nonreplacement sampling set of 3,000 Conditional Inference trees to identify influential factors from patient and surgical data. Mean comparison tests compared LOS and op time for top factors at statistically meaningful cut-offs to determine effect size. RESULTS Included: a total of 142 patients (61±11 years, 62%F) undergoing surgery for CD (8.2±4.5 levels; 49.3% posterior approach, 15.4% anterior, 35.2% combined). Mean overall LOS and op time: 7.2±8.7 days and 358±213 minutes, respectively. 30% of patients experienced E-LOS (14±13 days); mean EBL was 796±863cc. There was no difference in LOS across enrolling surgical centers (P=.837), or age, sex, comorbidity burden, and BL HRQLs between LOS groups (all P>.05). Overlapping predictors of both E-LOS and op time included levels fused (>7 increased LOS 2.7 days; >5 increased op time 96 minutes, both p 38kg/m2 increased LOS 8.1 days; >39kg/m2 increased op time 17 minutes), and osteotomy (increased LOS 2.0 days, op time 62minutes, both p 42mm increased LOS 2.1 days; >50mm increased op time 53 minutes, both p −0.9° increased LOS 3.8 days, >0.3° increased op time 71 minutes, both p 850cc increased 4.2 days, P CONCLUSIONS Baseline cervical malalignment, levels fused, and osteotomy were all predictors of both increased operative time and inpatient length of stay. Increased LOS and operative time also correlated with inferior 1-year clinical outcomes. These results can be used in future efforts to optimize patient care, hospital efficiency, and resource allocation.