The war at home against diabetes disparities

by Dean Schillinger, MD

During the recent decade-long Iraq and Afghanistan wars, 1,500 US soldiers lost a limb in combat. This tragedy was widely covered in the media and helped mobilize efforts to reduce exposure to threats in the Near East theatre, expedite troop withdrawals, and improve rehabilitation services for veterans. In that same period of time, over 1.5 million US residents suffered amputations as a result of Type 2 diabetes (DM2). While the number of amputations occurring on the home front as a result of DM2 exceeds that of the overseas front by a factor of 1,000, there is little public awareness of this war being waged at home. While clinicians, patients and families fight thousands of life- and limb-threatening battles on a daily basis, there is scant evidence that the US clinical and scientific community has truly mobilized for a public health war against DM2.

The DM2 epidemic is ground zero for the fight to achieve health equity. In this month’s issue of Health Affairs, startling new data were presented that demonstrate the robust and inexorable link between poverty and DM2 complications -- in this case non-traumatic amputations. Amputations are a disabling, disfiguring, and often preventable, complication of DM2. Recent nationwide data from the CDC suggest that amputations from DM2 have been gradually falling. Little is known about disparities in amputation rates, however. Taking a “hot-spot” approach that uses geographic data to explore health inequity, Carl D. Stevens et al. employed 2009 California hospital discharge data, census and zip code-level income, and statewide survey estimates of regional DM2 prevalence to generate amputation rates across various levels of poverty (measured at the community level). The research team found that the adjusted rate of amputations for neighborhoods that have >40% of households with income at 200% or below of federal poverty level was roughly double that for higher-income neighborhoods (those in which fewer than 10 percent of households have incomes below 200 percent of poverty). If one compared the extremes of poverty and wealth, however, those in the poorest neighborhoods had a 6-7 fold higher rate of amputation.

The authors of this landmark study discussed a number of possible mechanisms to explain these stark findings, focused mostly on suboptimal patient self-management behavior, as well as limited access to and poor quality of care, such as access to vascular surgeons and multidisciplinary limb salvage teams. They optimistically called out the Affordable Care act as one policy intervention that holds promise for reducing these alarming disparities. While better access to care and greater quality of care will certainly be important, I believe that the findings likely mask an even greater disparity---that of the differential burden of DM2 in low-income communities. Insofar as the results presented adjusted for background diabetes prevalence, the disparities in amputation rates are likely underestimate truth in the universe. In 2007 in California, 11.3% of residents with incomes between 100-199% of poverty level had DM2; among residents with incomes of 300% of poverty level and higher, the prevalence was 5.7%. As such, adjusting for background prevalence (making DM prevalence equal across California neighborhoods, in an attempt to isolate the neighborhood level effect of poverty) leads one to underestimate the effect of poverty on amputation by an additional factor of two. In addition, making such adjustments can lead clinicians and policymakers to neglect those interventions that would prevent diabetes in low-income communities, a critical pathway to reducing income-driven disparities in amputations.

If we are to achieve our Mission: Health Equity, we must continue to call out the gross injustices we see playing out in our clinics, our hospitals, our schools and our communities. And we must also employ all the tactics we have at our disposal, including those related public health, to engage in the war to honor the 1.5 million who lost their limbs in the last decade.