(I-634) Minimally Invasive Transforaminal Lumbar Interbody Fusion in Ambulatory Surgery Center versus Inpatient Setting: A One-Year Cost Utility Analysis

Introduction: In an effort to improve the efficiency of care by reducing costs and recovery time, Minimally Invasive Transforaminal Interbody Fusion (MIS-TLIF) is increasingly transitioning to outpatient settings. However, its safety and cost-effectiveness in an ambulatory surgery center (ASC) remain contentious, owing to no cost-utility studies for MIS-TLIF existing in the literature. Herein, we performed the first high-quality cost-utility analysis of patients undergoing single-level MIS-TLIF in the ASC versus the inpatient setting.

Methods: 775 consecutive, ASA I-III patients (675 inpatients prospectively enrolled in the National Quality Outcomes Database (QOD), 100 from our single ASC database) undergoing single-level MIS-TLIF were retrospectively reviewed, and propensity-matched to yield 100 pairs. Facility utilization, lost wages, and EQ5D quality of life (QOL) were evaluated over a one-year period. All patients were assumed to be commercially insured. Direct cost (one-year unit costs based on Medicare national allowable payment amounts) and indirect cost (missed workdays x average US daily wage) were assessed and incremental cost-effectiveness ratio (ICER) was calculated.

Results: The ASC cohort was younger, more frequently male, more frequently employed, and healthier (had lesser comorbidities) (p < 0.001). Estimated blood loss, length of surgery, and hospitalization were less for ASC vs. inpatient MIS-TLIF (p < 0.001). 90-Day readmission, reoperation rates, quality of life, and return-to-work rates were similar between both cohorts. Ambulatory MIS-TLIF was associated with significantly reduced direct costs ($36,000 vs. $54,500; p< 0.001), with a cost difference of $14,700 in total one-year costs and a similar gain in QALYs. A highly cost-ineffective ICER of $936,305/QALY-gained was seen with the inpatient cohort.

Conclusion : Inpatient vs. ambulatory MIS-TLIF is associated with increased healthcare costs without a safety, outcome, or QALY benefit. Hence, ASCs should be considered a value-based advancement for MIS-TLIF in appropriately selected patients.

How to Improve Patient Care: By adding more longitudinal and comprehensive studies analyzing the cost-utility of MIS TLIFs in an ASC, the patient, as well as the healthcare system as a whole can benefit from improved efficacy of care in spine surgery.