Determinants of cost-effectiveness in minimally invasive surgery for adult spinal deformity correction.

Abstract

The substantial financial implications of minimally invasive surgery for adult spinal deformity (ASD) necessitate a thorough assessment of its inherent value and efficacy. Factors contributing to protracted cost-effectiveness (CE) have not been examined in the context of minimally invasive spine surgery (MIS) for ASD (MIS-ASD). Investigating these determinants can yield pivotal insight to optimize the efficacy of such surgical interventions while concurrently moderating associated expenditures. MIS-ASD patients who underwent fusion > 2 levels with lateral lumbar interbody fusion or anterior lumbar interbody fusion and 4-year (4Y) follow-up were included. Published methods were used to determine the costs based on the Centers for Medicare & Medicaid Services definitions and average diagnosis-related group (DRG) reimbursement rates. Utility was calculated using quality-adjusted life years (QALYs), with a 3% discount applied for decline with life expectancy. Cost-utility (CU) was determined by dividing costs by total utility gained. Those who met CE at 4 years (CE4+) were evaluated relative to those who did not (CE4-). Eighty-six patients were included. Revision surgery occurred in 27% of patients. The overall mean cost was $73,000. CU at 4 years was $233,000, with 44% meeting CE4+ and a cumulative mean ± SD QALY gain of 0.8 ± 0.7. Among patients without revision, 54% met CE4+, while 76% met CE at life expectancy. There were no differences in length of stay, ICU admission rates, or time in ICU. Those with greater baseline disability (OR 1.1, p < 0.05) and frailty (OR 1.8, p < 0.05) had a higher likelihood of achieving CE4+. Lower comorbidity burden (i.e., lower Charlson Comorbidity Index score) was associated with increased odds of achieving CE4+ (OR 1.8, p < 0.05). Improved correction of pelvic incidence-lumbar lordosis mismatch was associated with achieving CE4+ (OR 3.8, p < 0.05). Those patients with major complications had 6× higher odds of failure to achieve CE4+, whereas those who underwent reoperation had 12× odds (both p < 0.05). MIS-ASD achieves CE in a significant subset of patients, particularly those with higher baseline disability, lower comorbidity burden, and better correction of spinal deformities. However, major complications and reoperations significantly hinder CE, underscoring the importance of optimizing patient selection and surgical techniques.