Location, Location, Location: Geographic Clustering of Lower-Extremity Amputation Among Medicare Beneficiaries With Diabetes

Abstract

OBJECTIVELower-extremity amputation (LEA) is common among persons with diabetes. The goal of this study was to identify geographic variation and the influence of location on the incidence of LEA among U.S. Medicare beneficiaries with diabetes.RESEARCH DESIGN AND METHODSWe conducted a cohort study of beneficiaries of Medicare. The geographic unit of analysis was hospital referral regions (HRRs). Tests of spatial autocorrelation and geographically weighted regression were used to evaluate the incidence of LEA by HRRs as a function of geographic location in the U.S. Evaluated covariates covered sociodemographic factors, risk factors for LEA, diabetes severity, provider access, and cost of care.RESULTSAmong persons with diabetes, the annual incidence per 1,000 of LEA was 5.0 in 2006, 4.6 in 2007, and 4.5 in 2008 and varied by the HRR. The incidence of LEA was highly concentrated in neighboring HRRs. High rates of LEA clustered in contiguous portions of Texas, Oklahoma, Louisiana, Arkansas, and Mississippi. Accounting for geographic location greatly improved our ability to understand the variability in LEA. Additionally, covariates associated with LEA per HRR included socioeconomic status, prevalence of African Americans, age, diabetes, and mortality rate associated with having a foot ulcer.CONCLUSIONSThere is profound “region-correlated” variation in the rate of LEA among Medicare beneficiaries with diabetes. In other words, location matters and whereas the likelihood of an amputation varies dramatically across the U.S. overall, neighboring locations have unexpectedly similar amputation rates, some being uniformly high and others uniformly low.

Diabetes, Lower-Extremity Amputation, and Death

“…The indication for an LEA is as variable as is the procedure itself (e.g., the part of the lower extremity removed). Recently, it was reported that the annual incidence of LEA is between 4 to 5 per 1,000 personyears in 5 million beneficiaries with diabetes in the U.S. Medicare population between 2006 and 2008 (14). There was also a three-to fivefold geographic variation in amputation incidence (14).…”

“…Recently, it was reported that the annual incidence of LEA is between 4 to 5 per 1,000 personyears in 5 million beneficiaries with diabetes in the U.S. Medicare population between 2006 and 2008 (14). There was also a three-to fivefold geographic variation in amputation incidence (14). Similarly, a study in 2012 by Holman et al (27) demonstrated an incidence of LEA in those with diabetes of ;2.5 per 1,000 person-years and also noted an eightfold geographic variation in LEA rates among the Primary Care Trusts in England.…”

“…However, 30-day postoperative mortality can approach 10%, with most mortality associated with those receiving an LEA as an emergency procedure or with the presence of preoperative sepsis (11,12). Previous reports have estimated that the 1-year post-LEA mortality rate in people with diabetes is between 10 and 50%, and the 5-year mortality rate post-LEA is between 30 and 80% (4,(13)(14)(15). More specifically, in the U.S. Medicare population mortality within a year after an incident LEA was 23.1% in 2006, 21.8% in 2007, and 20.6% in 2008 (4).…”

A perifériás verőérbetegséggel és a cukorbetegséggel összefüggő alsó végtagi amputációk. Epidemiológiai adatok bemutatása és a megelőző stratégia lehetőségeinek elemzése

“…Az Amerikai Egyesült Államok, Egyesült Királyság, valamint Finnország által közölt adatok szerint az adott ország különböző terüle-teinek amputációs incidenciaadatai 1,3-8,6-szeres kü-lönbséget mutathatnak [19,23,24]. Ezeknek a vizsgála-toknak az eredményei térségi autokorrelációt jeleztek, azaz az egymással szomszédos területek incidenciaadatai jellemzően közelebb állnak egymáshoz, mint az egymás-tól távoli területeké [23].…”

Lower-Extremity Amputation Risk Is Associated With Variation in Behavioral Risk Factor Surveillance System Responses

“…Variation exists both between countries and within a country. For example, there is an approximate twofold variation in the incidence of LEA between the U.K. and the U.S. (5,7). A study published in 2011 (5) in the U.S. demonstrated a nearly fourfold variation within the U.S. and further showed that increased incidence of LEA was clustered in contiguous regions within the U.S.…”