Methods: Data were obtained from the American College of Surgeons National Surgical Quality Improvement Program database. Patients aged ≥18 years who underwent surgery for spinal deformity between 2011 and 2019 were identified and included. To ensure a homogenous patient cohort, those who underwent anterior-only and concurrent anterior-posterior fusions were excluded. Propensity score matching analysis was performed, and Mann-Whitney U test, Pearson chi-square test, or Fisher’s exact test were used to compare matched cohorts as appropriate. Results: A total of 326 patients who underwent revision surgery were matched with 206 primary surgery patients via propensity score matching. Demographic characteristics, comorbidities, preoperative laboratory values, and readmission and reoperation rates were not significantly different between groups. The revision surgery group had significantly higher mean RVUs per minute than that of the primary surgery group (0.331 vs. 0.249, p <0.001), as well as rates of morbidity and blood transfusion. Conclusions Compared to primary surgery, revision surgery for ASD is associated with significantly higher RVUs per minute and total RVUs and higher rates of 30-day morbidity and blood transfusions. Readmission and reoperation rates are similar between surgeries.

Methods: Patients who underwent PCDF from 2005 to 2018 were identified using the National Surgical Quality Improvement Program database. Regression analysis was utilized to compare primary outcomes between surgical settings and evaluate for predictors thereof. Results: We identified 8,912 patients. Unadjusted analysis revealed that outpatients had lower readmission (4.7% vs. 8.8%, p =0.020), reoperation (1.7% vs. 3.8%, p =0.038), and morbidity (4.5% vs. 11.2%, p <0.001) rates. After adjusting for baseline differences, readmission, reoperation, and morbidity no longer statistically differed between surgical settings. Outpatients had lower operative time (126 minutes vs. 179 minutes) and levels fused (1.8 vs. 2.2) (p <0.001). Multivariate analysis revealed that age (p =0.008; odds ratio [OR], 1.012), weight loss (p =0.045; OR, 2.444), and increased creatinine (p <0.001; OR, 2.233) independently predicted readmission. The American Society of Anesthesiologists (ASA) classification of ≥3 predicted reoperation (p =0.028; OR, 1.406). Rehabilitation discharge (p <0.001; OR, 1.412), ASA-class of ≥3 (p =0.008; OR, 1.296), decreased hematocrit (p <0.001; OR, 1.700), and operative time (p <0.001; OR, 1.005) predicted morbidity. Conclusions The 30-day outcomes were statistically similar between surgical settings, indicating that PCDF can be safely performed as an outpatient procedure. Surrogates for poor health predicted negative outcomes. These results are particularly important as we continue to shift spinal surgery to outpatient centers. This importance has been highlighted by the need to unburden inpatient sites, particularly during public health emergencies, such as the coronavirus disease 2019 pandemic.