Trends in Lumbar Fusion Procedure Rates and Associated Hospital Costs for Degenerative Spinal Diseases in the United States, 2004 to 2015

Study Design. Analysis of National Inpatient Sample (NIS), 2004 to 2015. Objective. Describe recent trends in US rates of lumbar fusion procedures and associated costs, by surgical indication. Summary of Background Data. Spinal fusion is appropriate for spinal deformity and instability, but evidence of effectiveness is limited for primary disc herniation and spinal stenosis without instability. It remains controversial for treatment of axial pain secondary to degenerative disc disease. There are potential non-instability, non-deformity indications for fusion surgery, including but not limited to severe foraminal stenosis and third-time disc herniation. Methods. Elective lumber fusion trends were reported using Poisson regression, grouped by indication as degenerative scoliosis, degenerative spondylolisthesis, spinal stenosis, disc herniation, and disc degeneration. Generalize linear regression was used to estimate trends in hospital costs, adjusted for age, sex, indication, comorbidity, and inflation. Results. Volume of elective lumbar fusion increased 62.3% (or 32.1% per 100,000 US adults), from 122,679 cases (60.4 per 100,000) in 2004 to 199,140 (79.8 per 100,000) in 2015. Increases were greatest among age 65 or older, increasing 138.7% by volume (73.2% by rate), from 98.3 per 100,000 (95% confidence interval [CI] 97.2, 99.3) in 2004 to 170.3 (95% CI 169.2, 171.5) in 2015. Although the largest increases were for spondylolisthesis (+47,390 operations, 111%) and scoliosis (+16,129 operations, 186.6%), disc degeneration, herniation, and stenosis combined to accounted for 42.3% of total elective lumbar fusions in 2015. Aggregate hospital costs increased 177% during these 12 years, exceeding $10 billion in 2015, and averaging more than $50,000 per admission. Conclusion. While the prevalence of spinal pathologies is not known, the rate of elective lumbar fusion surgery in the United States increased most for spondylolisthesis and scoliosis, indications with relatively good evidence of effectiveness. The proportion of fusions coded for indications with less evidence of effectiveness has slightly decreased in the most recent years. Level of Evidence: 3