Introduction: As a top five and growing category of CMS expenditure, spinal surgeries represent an important area for analysis of both cost drivers and outcome effectors. Relative to other literature, this research analyzes a broader spectrum of spine surgeries and emphasizes trends in hardware.
Methods: We retrospectively analyzed 1,684 patients (mean age 66, female 54%) who underwent single- or multi-level spinal fusion (mean levels 3.88; median 2.00) at a large medical center with an enhanced recovery program and multidisciplinary spine clinic between October 2016 and November 2021. Time series regressions were used to evaluate trends in hospital, provider, and hardware cost categories. Multivariate regression and power analysis were used to evaluate surgery cost drivers. Covariates included age, gender, body mass index, comorbidities, length of stay, and anesthesia duration. Adjustments for inflation and seasonality were performed using the U.S. healthcare consumer price index.
Results: Hardware costs (mean[SD] $82,761[$58,407]) trended down by $640 [CI:-770.89,-508.29] per patient per month, robust to inflation and seasonality adjustments. No change in hardware count per patient was detected. Hospital costs ($20,025 [$14,417] exhibited an average monthly increase of $146 [CI:82.58,210.46] per patient. Provider costs ($26,953[$11,461]) show a negative inflation-adjusted trend of $28. Thirty-day complications demonstrated negligible explanatory power of costs. Congestive heart failure and cancer history were the only comorbidities with predictive power, p-values=0.01 and 0.03 respectively. An additional hour under anesthesia was associated with a $10,130 cost increase (p-value < 0.001).
Conclusion : Monthly hardware and provider costs trended down per patient over our study period, while hospital costs significantly increased. Anesthesia duration and level of instrumentation represent two significant cost drivers that may be leveraged to reduce spine surgery costs. Notably, costs associated with post-operative complications are unlikely to be determined ex ante.
