P79. Prevalence and surgical outcomes of primary severe sagittal plane deformity (pSPD) in adult spinal deformity (ASD) surgery: comparison between Japan and the United States

Abstract

BACKGROUND CONTEXT Primary severe sagittal plane deformity (pSPD) is a distinct form of ASD commonly seen in Asian countries. The prevalence and surgical outcomes of pSPD are still poorly understood. PURPOSE The aim of this study was to report the prevalence and to compare clinical outcomes of pSPD between Japan (JP) and the US. STUDY DESIGN/SETTING Multicenter retrospective case series of surgically treated ASD patients. PATIENT SAMPLE A total of 345 consecutive, surgically treated primary ASD patients (JP:181, US:164) with age >50y and minimum 2-yr followup were included (JP vs US; age: 63±9vs 65±9). OUTCOME MEASURES Baseline and 2yr postop SRS22 were used to assess the clinical outcomes. METHODS This was a retrospective review of two prospective multicenter databases in JP and US. pSPD included primary patients (no previous fusion) with C7SVA>9.5cm, PT>20o, PI-LL>30o, and Cobb angle RESULTS Prevalence of pSPD in surgically treated ASD was significantly higher in JP (20% vs 12%, p=0.01). In both countries, gender, BMI, and Charlson Comorbidity Index were comparable with other ASD types, while baseline ODI and SRS22 (function and appearance) for pSPDs were poorer than other ASD types in the US. Although pSPDs had worse sagittal alignment at 2 yrs, similar HRQL improvement was observed in both countries with equivalent complication rates compared with other ASDs (Table). Baseline SRS22 function, pain, and appearance were significantly worse in the US, while SRS22 mental health was worse in JP (function: 2.5±0.8vs 2.7±0.8, pain: 2.2±0.7vs 2.8±0.7, appearance: 2.1±0.7vs 2.4±0.8, mental health; 3.3±1.2vs 2.6±0.7, p CONCLUSIONS Prevalence of pSPD in surgically treated ASD was significantly higher in JP (20% vs 12%, p=0.01). pSPD patients had worse HRQL at baseline compared with other ASDs. However, equivalent improvement for HRQL was observed in both countries with comparable complication rates and similar surgical invasiveness. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.