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Regional Hospital Competition Increases Rates Of Lower Extremity Advanced Limb Salvage For Chronic Wounds
Kenneth L. Fan, MD, Jenna C. Bekeny, BA, Elizabeth G. Zolper, BS, Christopher E. Attinger, MD, Karen K. Evans, MD, Derek DeLia, PhD.
MedStar Georgetown University Hospital, Washington, DC, USA.

Purpose: Wounds in the comorbid population require advanced limb salvage to prevent amputation. Amputation results in increased mortality rates due to exacerbation of comorbidities. Extensive health economics literature demonstrates hospital activities are influenced by level of market concentration. The impact of competition and market concentration on delivery of limb salvage modalities remains to be determined. This study seeks to perform an initial examination on the influence of market forces on delivery of limb salvage to the chronic wound.
Methods: Admission for chronic lower extremity wounds were identified in the 2010-2011 National Inpatient Survey (NIS) using ICD-9-CM diagnosis codes. The study cohort consisted of admitted patients receiving amputations, limb salvage without flap techniques (e.g. skin grafts), or limb salvage with flap techniques (e.g. pedicled or free flaps). The general Herfindahl-Hirschman Index (HHI), the sum of the squared market share for all hospitals within a designated market as provided by the NIS, was used to measure hospital competition. HHI <1500 indicates an unconcentrated/competitive markets, 1500-2500 indicates moderately concentrated, and >2500 indicates a highly concentrated (with patients)/non-competitive. Rural markets were eliminated from the analysis, as they are considered monopolies in their respective markets. HHI within a variable radius that captures 90% of the hospital's discharges was selected after sensitivity analysis. Multinomial regression analysis accounting for the complex survey design of the NIS was used to determine the independent contribution of factors expressed as marginal effects.
Results: The study cohort represents 165,420 admissions nationally: 118,126 amputations, 36,524 limb salvage without flap techniques, and 10,752 limb salvage flap techniques were identified. Diabetics accounted for 64.1% of this cohort. Of all lower extremity flaps performed in this cohort, 56.6% occurred in competitive markets, 15.1% in medium markets, and 9% in concentrated markets (p<0.0001). Patients treated in competitive markets tend to be from densely populated areas of counties >1,000,000 (p<0.0001). 55% of all urban teaching hospitals are in highly competitive markets, while 35.5% of all urban nonteaching hospitals are in highly competitive environments (p<0.0001)
In a multivariable model, lower limb salvage with flaps are 2.64 percentage points (PP) more likely to be performed in highly competitive markets compared to highly concentrated markets (p=0.001). Patients with private insurance were 1.93 PP more likely to receive limb salvage with flaps (p=0.022). Patients who are >65 or Black are 2.74 and 2.33 PP less likely to receive advanced limb salvage (p<0.0001). While Charlson Comorbidity Index had no impact on receipt of limb salvage with flaps, those with a history of critical limb ischemia were 10.3 PP less likely to receive limb salvage with flaps (p<0.0001).
Conclusion: In an analysis eliminating rural markets, higher rates of lower extremity flaps may be explained by decreased patient concentration and increased hospital competition. Further examination is necessary to inform stakeholders in development of a multifaceted strategy in access and utilization of reconstructive limb services.


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