National trends and regional differences in costs and outcomes of single level microdiscectomy: 2016-2022

Introduction: Rates of microdiscectomy, the gold standard for the treatment of lumbar disc herniation, have grown in the United States alongside an aging population with increasing comorbidities. However, there is little data available regarding the geographic distribution of microdiscectomy volume, surgical outcomes, and cost. This study provides a regional, epidemiological overview of microdiscectomy to better understand the impact of this procedure on the American health system.

Methods: A large national cross-sectional administrative database (Premier Health Database)was queried for patients that underwent single-level microdiscectomy between January 2016 and June 2022. Patients were divided into the census bureau division where their surgery was performed. Total surgical costs, defined as expenses a facility (hospital or surgery center) incurred for providing a ssingle-levelmicrodiscectomy procedure, were recorded and adjusted for inflation. Readmission and reoperation statistics were also recorded. Cost and outcomes over time were compared between regions. In a multivariate analysis, regional differences in costs and outcomes were adjusted for patient comorbidities, demographics, and time fixed effects.

Results: The study included 156,146 patients (45.1%Female, 6.8%Black, 25.7%Medicare). National 180-day readmission and reoperation rates were 5.6% and 3.3%, respectively. The Middle Atlantic had the lowest rates (4.9%,2.7%), while West South Central had the highest (6.2%,3.4%). Average surgical costs significantly decreased in the Mountain region (-14.8%) but increased in the Pacific (+27.0%). In multivariate analysis, total surgical costs were significantly higher in every region compared to East South Central, except in West North Central with a mean difference of -$436. Despite lower costs, West North Central had significantly lower odds of 180-day readmission and reoperation (0.8 [0.73,0.89] and 0.85 [0.77,0.94]). In the Middle Atlantic, East North Central, South Atlantic, and Pacific, higher costs were accompanied by significantly lower odds of adverse outcomes.

Conclusion : There is a large regional variation in the cost and outcomes of microdiscectomy. Since 2016, costs have increased in almost every region with a corresponding decrease in readmission and reoperation rates. After adjusting for comorbidities, most regions that incurred higher costs had statistically significantly low reoperation and readmission odds. Further study into cost categories that are driving the increase in costs of microdiscectomy is warranted.