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 Impact of Competition on Hospitals’ Early Adoption of Endovascular Repair Studied  

 Researchers consider hypothesis that early adopters in competitive markets might have improved outcomes  


CHICAGO─The share of total abdominal aortic aneurysms (AAA) repairs in the United States performed by endovascular aneurysm repair (EVAR) has increased rapidly from 32 percent in 2001 to 65 percent in 2006, with considerable variation between the states. A new study, published in the September issue Journal of Vascular Surgery®, examines the hypothesis that hospitals in competitive markets adopted EVAR early and had improved AAA repair outcomes. 
Louis L. Nguyen, MD, MBA, MPH, is a vascular surgeon at Brigham and Women's Hospital and associate professor of surgery at Harvard Medical School, in Boston, Mass. He, along with fellow researchers, queried the Nationwide Inpatient Sample and linked Hospital Market Structure (HMS) data for patients who underwent repair EVAR for non-ruptured AAA in 2003. They also queried the same cohort of patients for post-AAA repair outcomes including in-hospital death, length of stay, and vascular complications (including graft complication, embolism, or infection), and major postoperative complications as defined by the national Surgical Quality Improvement Program (NSQIP).
“In the HMS, the Herfindahl Hirschman Index (HHH, range 0-1) is a validated and a widely accepted economic measure of competition,” said Dr. Nguyen. “Hospital markets were defined using a variable geographic radius that encompassed 90 percent of discharged patients. Market definition accounts for the fact that hospitals do not compete within confined geographic boundaries.” 
“We found that greater hospital competition in 2003 was significantly associated with increased EVAR adoption at a time when diffusion of this technology passed its tipping point,” said Dr. Nguyen. “However, hospital competition does not influence post-AAA repair outcomes, but might improve outcomes like in-hospital mortality and length of stay.” 
“Our findings suggest that adoption of novel vascular technology is not solely driven by clinical indications, but may be influenced by market forces,” added Dr. Nguyen. “For example, hospitals in competitive markets may be more likely to distinguish themselves from the competition by offering new procedures or services, especially when there are distinct differences included in procedures such as EVAR. The hospitals also may have a higher volume, greater expertise, and greater resources to become early adopters.”  In addition, said Dr. Nguyen, people generally think that if there is more competition, costs will be lowered for a product or healthcare, but evidence suggests that competition may not impact cost or even increase it.
A weighted total of 21,600 patients was included in the analyses. Of these patients, 48.52 percent had EVAR. Patients at more competitive hospitals (lower HHI) were at increased odds of undergoing EVAR vs. open repair (odds ratio, 1.127 per 0.1 decrease in HHI; P < .0127) after adjusting for patient demographics, comorbidities and hospital level factors (bed size, teaching status, AAA repair volume, and ownership). Competition was not associated with differences in in-hospital mortality or vascular, neurologic, or other minor postoperative complications.
A bivariate and multivariable linear and logistic regression analyses for the dependent variable of including state level variables (number of malpractice claims, average malpractice claim payment, average number of vascular surgeons, and average health expenditures per state) were included to control for potential confounders in previous studies. A propensity score-adjusted multivariable logistic regression model was used to control for treatment bias in the assessment of competition on AAA repair outcomes. 
Researchers noted that their results may help guide future healthcare policy designed to limit growing costs associated with vascular technology development.
About Journal of Vascular Surgery®
The Journal of Vascular Surgery® provides vascular, cardiothoracic and general surgeons with the most recent information in vascular surgery. Original, peer-reviewed articles cover clinical and experimental studies, noninvasive diagnostic techniques, processes and vascular substitutes, microvascular surgical techniques, angiography and endovascular management. Special issues publish papers presented at the annual meeting of the Journal’s sponsoring society, the Society for Vascular Surgery®. Visit the Journal Web site at

About the Society for Vascular Surgery
The Society for Vascular Surgery® (SVS) is a not-for-profit professional medical society, composed primarily of vascular surgeons, that seeks to advance excellence and innovation in vascular health through education, advocacy, research, and public awareness. SVS is the national advocate for 4,600 specialty-trained vascular surgeons and other medical professionals who are dedicated to the prevention and cure of vascular disease. Visit its Web site at®.

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