Authors: Seungwon Yoon; Oliver Tang; Michael Lawton, MD (New Haven, CT)

Introduction Several studies have documented improved outcomes at high-volume hospitals for neurosurgical procedures. However, the relationship between neurosurgical volume and costs remains poorly understood. Methods Using neurosurgery-specific 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 analyses to examine the impact of case volume on inpatient costs. Multivariate regression adjusted for patient age, sex, race, insurance, income, severity of illness, length of stay, emergency admission, wage index, hospital ownership, location/teaching status, hospital region, and DRG weights. We created a model for centralization of neurosurgical care, where non-emergency admissions with minor risk of mortality were considered as transfer candidates. Results 12,129,029 total admissions underwent neurosurgery from 2002 to 2014, with 59.6% treated at high-volume hospitals. Patients at high-volume centers were more likely to privately insured, present with higher risk of mortality, and undergo higher DRG-weight procedures than those at low-volume centers ( P <0.001). High-volume hospital admissions were on average 9% or $1,791 more expensive than their low-volume counterparts. However, following 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). If 10% of transfer candidates were rather treated at high-volume centers, we estimate an annual saving of $192 million, culminating in a total saving of $2.5 billion. Conclusion High-volume institutions appear to have higher costs due to their case-mix of higher patient and procedural severity. After adjusting for this, we found that treating a similar patient at a low-volume hospital would be 4.3% more expensive, suggesting that high-volume hospitals may provide more cost-effective neurosurgical care. Amidst sharply rising medical costs, treatment at high-volume neurosurgical institutions may be a promising strategy to delivering higher value care.