The Association Between Geographic Density of Infectious Disease Physicians and Limb Preservation in Patients With Diabetic Foot Ulcers

Abstract

Background: Avoiding major (above-ankle) amputation in patients with diabetic foot ulcers is best accomplished by multidisciplinary care teams with access to infectious disease specialists. However, access to infectious disease physicians is partially influenced by geography. We assessed the effect of living in a hospital referral region with a high geographic density of infectious disease physicians on major amputation for patients with diabetic foot ulcers. We studied geographic density, rather than infectious disease consultation, to capture both the direct and indirect (eg, informal consultation) effects of access to these providers on major amputation.

Methods: We used a national retrospective cohort of 56440 Medicare enrollees with incident diabetic foot ulcers. Cox proportional hazard models were used to assess the relationship between infectious disease physician density and major amputation, while controlling for patient demographics, comorbidities, and ulcer severity.

Results: Living in hospital referral regions with high geographic density of infectious disease physicians was associated with a reduced risk of major amputation after controlling for demographics, comorbidities, and ulcer severity (hazard ratio, .83; 95% confidence interval, .75-.91; P < .001). The relationship between the geographic density of infectious disease physicians and major amputation was not different based on ulcer severity and was maintained when adjusting for socioeconomic factors and modeling amputation-free survival.

Conclusions: Infectious disease physicians may play an important role in limb salvage. Future studies should explore whether improved access to infectious disease physicians results in fewer major amputations.

Keywords: geographic variation; infectious disease providers; major amputation; multidisciplinary teams.

Figure 1.

Geographic density of infectious disease physicians in each hospital referral region (HRR) within the United States, 2006. Density was characterized as above or below the median (1.09/10 000 Medicare enrollees in a HRR). Outliers were identified using the blocked adaptive computationally efficient outlier nominators algorithm.