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Blacks with diabetes at higher risk for amputation, PAD complications than whites
Black patients in the United States with diabetes and peripheral arterial disease receive less preventive care and have less success with interventional procedures, resulting in a higher rate of limb amputation, according to a recent report published by The Dartmouth Institute.
“This report reveals significant variation in the approaches to the treatment of diabetes and [peripheral arterial disease] chosen by patients and physicians. These differences are striking, not only for preventive treatments, but also in the use of invasive treatments designed to limit the devastating effects of these diseases,” the researchers wrote. “This report suggests that, while a comprehensive approach is necessary, focusing on black patients in poor, rural regions of the United States is likely to be the best place to start. This approach will have the most impact — and likely the greatest challenge towards implementation — as high limb loss rates have been a part of life for many years in rural portions of the southern United States.”
The report was based on a study of diagnostic codes of patients that included both diabetes and peripheral arterial disease (PAD). The researchers examined the incidence of each event between 2001 and 2011. They defined rates of vascular procedures and assessed differences in outcomes, using t tests to compare rates among regions.
Preventive testing
Preventive measures among patients with diabetes and PAD varied widely among regions and between races, according to the report.
“Given that preventive treatments are evidence-based, nearly universally available, and inexpensive, one might expect that their use would be high. However … there are marked differences in the use of these basic services in different regions of the United States,” researchers wrote.
In 2010, 80.7% of patients with diabetes had at least one lipids test, but rates in Central and Mountain states were much lower — 53.9% in Wyoming and 60.9% in New Mexico — than Florida, for example, which had rates around 89%.
Additionally, 81.5% of nonblack patients with diabetes underwent lipid testing while 75.2% of black patients with diabetes did the same.
Testing of HbA1c was completed in 83.8% of patients overall, but Southern and Western regions had lower rates — 66.9% in New Mexico, 69.8% in Alaska and 73.8% in Oklahoma — than the upper Midwest, where Iowa, Minnesota and Wisconsin hovered around 92%.
Nonblack patients with diabetes had a rate of HbA1c testing of 84.2%, whereas 80.9% of black patients with diabetes had their HbA1c tested.
Endovascular interventions
As with testing, the researchers found that interventional measures, such as endovascular procedures, varied widely among regions of the country and between races.
“For patients with diabetes and PAD, preventive measures are underused, especially for black patients, and their use varies nationwide. Similarly, the use of revascularization treatments also varies dramatically for patients with diabetes and PAD,” the researchers wrote.
On average, 14.1 per 1,000 Medicare beneficiaries underwent endovascular intervention. Regionally, the sites in Georgia, Colorado and Hawaii had fewer than six procedures per 1,000, whereas Michigan and Indiana had more than 30 procedures per 1,000 beneficiaries.
Nationally, black patients were more likely to receive these interventions (19.7 per 1,000 vs. 13.3 per 1,000 in nonblack patients), although those rates still varied by region. Fewer than five in 1,000 black beneficiaries in Georgia received the treatment, whereas more than 40 in 1,000 underwent the procedure in Louisiana, Texas and Mississippi.
Nationally, open leg bypass surgery rates varied from fewer than two to more than nine per 1,000, but rates were approximately 30% higher among black patients vs. nonblack patients (5.2 vs. four per 1,000).
“While the rates of revascularization were higher among black patients in many regions, the extent of variation for both endovascular procedures and open bypass surgery was much more dramatic among black patients, indicative of a poorer understanding of what works best to limit amputation risk for these high-risk patients,” the researchers wrote.
Amputation rates
Lastly, the researchers looked at amputation rates among patients with diabetes and PAD, showing that rural areas of the southeastern United States had higher rates of major amputation.
“Across the United States, the risk of amputation averages between two and three per 1,000 patients with diabetes and [PAD]. However, this rate can be up to eight times higher in some places, especially among black patients. In fact, when comparing black and nonblack patients, the lowest-risk black patients have higher risk of amputation than nearly all nonblack patients,” researchers wrote.
From 2007 to 2011, the national average rate of leg amputation was 2.4 per 1,000 Medicare beneficiaries who had both diabetes and PAD. In states such as Michigan and Florida, rates were 1.2 per 1,000, whereas in Mississippi and Wisconsin, the rate was more than six per 1,000.
On a national level, the rate of amputation among black patients with diabetes and PAD was 5.6 per 1,000, whereas all other beneficiaries carried a rate of only two per 1,000. Amputation in black patients showed a similar variance between regions with only two per 1,000 in California and Nevada, but more than 14 per 1,000 in Virginia and Mississippi.
Specifically, rates of amputation among nonblacks was 4.1 per 1,000 in Lynchburg, Va., whereas the same city had a rate of 14 per 1,000 for black patients. Tupelo, Miss., had a nonblack amputation rate of 4.7 per 1,000 and a black amputation rate of 16.1 per 1,000.
“These data leave little doubt where the focus on amputation prevention needs to be directed,” the researchers wrote.
Disclosure: The Dartmouth Institute has received a grant from the Robert Wood Johnson Foundation, in partnership with a funding consortium including the WellPoint Foundation, the United Health Foundation and the California HealthCare Foundation.