Volume-Cost Relationship in Neurosurgery: Analysis of 12,129,029 Admissions from the National Inpatient Sample

Abstract

Background/objective: Several studies have documented improved outcomes at high-volume hospitals for neurosurgery. However, the relationship between neurosurgical volume and costs remains poorly understood.

Methods: Using neurosurgery-specific Diagnosis-Related Groups (DRG) codes, we identified adult neurosurgical admissions in the National Inpatient Sample from 2002 to 2014. We stratified hospitals by annual neurosurgical volume as high-volume (top 20%) or low-volume centers (bottom 80%). We performed survey-weighted regression analyses to examine the impact of case volume on inpatient costs.

Results: A total of 12,129,029 admissions underwent neurosurgery from 2002 to 2014, with 59.6% treated at high-volume hospitals. Patients at high-volume centers were more likely to have private insurance, higher risk of mortality scores, and higher DRG weight procedures than those at low-volume centers (P < 0.001). High-volume hospital admissions were on average 9% or $1791 more expensive than their low-volume counterparts. However, after adjustment for patient, hospital, and case-mix differences, high-volume hospitals were 4.3% less expensive than low-volume centers ($21,825 vs. $22,924; P < 0.01). The southern United States, which had the biggest volume, showed the highest savings (6.5%).

Conclusions: High-volume hospitals provide more cost-effective neurosurgical care. Centralization of care at high-volume neurosurgical institutions may be a promising strategy to delivering higher-value care, achieving better outcomes at lower costs.

Keywords: Centralization of surgery; Health care economics; Value-based health care; Volume–cost.