1399. Interhospital Competition Predicts Treatment and Outcomes for Unruptured Aneurysms

Award: Third Place Socioeconomic Eposter Award

Authors: Oliver Tang; Seungwon Yoon; Wesley Durand; Shaan Ahmed, AB; Michael Lawton, MD (Providence, RI)


Previous studies have suggested that interhospital competition influences patient outcomes, hospital costs, and adoption of new treatments. Advances in imaging and treatment strategies make unruptured intracranial aneurysms (UIAs) a promising model for assessing how competition impacts neurosurgery.


We identified all elective UIA admissions (ICD-9-CM diagnosis code 437.3) in the National Inpatient Sample from 2000, 2003, 2006, and 2009, which record the Herfindahl-Hirschman Index (HHI). The HHI is a validated measure of hospital market competition that ranges from 0 (significant competition) to 1 (monopolization). We assessed how HHI was associated with treatment strategy (no surgery, clipping, or coiling), mortality, inpatient complications, length of stay, and hospital costs. Multivariate regression adjusted for nine confounding variables: patient characteristics (age, sex, insurance, Charlson Comorbidity Index), hospital characteristics (region, location/teaching status, bed size, ownership), and year. We reported odds ratios (ORs) for binary outcomes and percent changes for continuous outcomes, with all results corresponding to a 0.1 decrease in HHI (greater competition).


50,666 total elective UIA admissions were analyzed. Patients at hospitals in more competitive markets were more likely to receive UIA intervention (OR=1.26, P<0.001). Hospitals facing more competition were also more likely to perform coiling over clipping for UIA intervention (OR=1.34, P=0.009). For patient outcomes, greater interhospital competition was associated with increased odds of inpatient complications (OR=1.12, P=0.009) and higher hospital costs (+9%, P<0.001). Specifically, there was increased risk of hemorrhagic (OR=1.23, P=0.01) and neurologic complications (OR=1.36, P=0.002). However, there were no significant differences observed for length of stay (P=0.10) or inpatient mortality (P=0.55).


Increased interhospital competition was associated with higher odds of surgically treating UIAs, preference of coiling over clipping, greater likelihood of complications, and elevated hospital costs. Amidst trends like practice consolidation and reimbursement reform, further research should characterize the mechanisms by which competition may affect these outcomes.