Comparison of Value per Operative Time between Primary and Revision Surgery for Adult Spinal Deformity: A Propensity Score-Matched Analysis

Study design: Retrospective cohort study.

Purpose: To compare the relative value units (RVUs) per minute of operative time between primary and revision surgery for adult spinal deformity (ASD).

Overview of literature: Surgery for ASD is technically demanding and has high risks of complications and revision rates. This common need for additional surgery can increase the overall cost of care for ASD. RVU is used to calculate reimbursement from Medicare and to determine physician payments nationally. In calculating RVUs, the physician's work, the expenses of the physician's practice, and professional liability insurance. Cost effectiveness of surgeries for ASD have been evaluated, except for RVUs per minute compared between primary and revision surgery.

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.