Cost-effectiveness Improves for Operative Versus Non-operative Treatment of Adult Symptomatic Lumbar Scoliosis at Eight-year Follow-up

Abstract

Study Design. Secondary data analysis of the NIH-sponsored study on adult symptomatic lumbar scoliosis (ASLS). Objectives. The purpose of this study is to perform a cost-effectiveness analysis comparing operative (Op) versus non-operative (Non-Op) care for ASLS 8 years after enrollment. Background. A prior cost-effectiveness analysis of the current cohort comparing Op to Non-Op care at 5 years after enrollment showed an incremental cost-effectiveness ratio (ICER) of $44,033 in the as-treated analysis and an ICER of $27,480 in the intent-to-treat analysis. Materials and Methods. Data were collected every 3 months for the first 2 years, and then every 6 months for the remainder of the study. Data included the use of Non-Op modalities, medications, and employment status. Costs for index and revision surgeries and Non-Op modalities were determined using Medicare Allowable rates. Medication costs were determined using the RedBook and indirect costs were calculated based on reported employment status and income. Quality-adjusted life years (QALYs) were determined using the Short Form-6 Dimensions. Results. There were 101 cases in the Op and 103 in the Non-Op group with complete 8-year data. Thirty-eight patients (37%) in the Non-Op group had surgery from 3 to 72 months after enrollment. An as-treated analysis including only cases who never had surgery (N = 65) or cases with complete 8-year postoperative data (N = 101) showed that Op treatment was favored with an ICER of $20,569 per QALY gained, which is within willingness-to-pay thresholds. An intent-to-treat analysis demonstrated greater QALY gains and lower costs in the Op group (ICER = -$13,911). However, intent-to-treat analysis is influenced by Non-Op patients who crossed over to Op treatment at variable times during follow-up. Conclusion. Op treatment was more cost-effective than Non-Op treatment for ASLS at 8-year follow-up. The ICER continued to improve as compared with the 5-year values ($20,569 vs. $44,033).