Their analysis, published online Monday by the journal Health Affairs, pinpointed amputation "hot spots" where as many as 10.7 out of 1,000 diabetic adults ages 45 and older wound up losing a lower limb because of complications of diabetes.
San Fernando, Compton and broad swaths of South and East L.A. had some of the highest amputation rates. In ZIP Codes with the lowest amputation rates -- including many affluent areas such as Malibu, Beverly Hills and Santa Clarita -- no more than 1.5 diabetics per 1,000 lost a limb to the disease.
On the Palos Verdes Peninsula, adjacent ZIP Codes landed on opposite ends of the scale, with South Bay cities having among the lowest levels of amputations among diabetics and San Pedro having among the highest.
"This represents an intolerable health disparity," said study lead author Carl Stevens, a professor of medicine at UCLA's David Geffen School of Medicine. "Where the poor people are is where the amputations are."
Stevens said that the higher incidence of amputations among diabetics in lower-income ZIP Codes was almost certainly related to two factors: difficulties patients in those neighborhoods had in getting access to primary care, and hurdles they faced in understanding how to manage their condition.
Amputations due to diabetes are preventable, he said, through careful control of blood sugar and lipid levels and other health risks. But when diabetes goes unchecked over the course of many years, it can set off a cascade of complications. Blood vessels suffer damage, impairing circulation to the feet. Damaged nerves can make it hard for diabetic patients to realize when they've suffered an injury or a cut and treat it properly. Reduced immunity can then lead to limb-threatening infections.
To conduct their analysis, the team examined patient discharge records compiled by the California Office of Statewide Health Planning and Development, identifying the number of "non traumatic" amputations in diabetic patients for each ZIP Code. The researchers then used census data to identify income levels and UCLA's California Health Interview Survey to estimate diabetes incidence for each ZIP Code.
In all, the researchers identified nearly 8,000 diabetes-related amputations in 6,828 people. In Los Angeles, they reported, the amputation rate for people with diabetes in neighborhoods where more than 40% of households have incomes below 200% of poverty, or $31,460 for a household of two, was about twice that of neighborhoods in which fewer than 10% of households fell below that line.
"We have a safety net with big holes in it," Stevens said.
The outlook isn't entirely grim, he noted. Monday's study used patient data from 2009, before the rollout of the Affordable Care Act, which greatly increased the number of Californians covered through Medi-Cal, the state's healthcare program for the poor. Provided there are enough primary care doctors in the system, Stevens said, and with improvements in patient education, many low-income patients should have better access to primary care services than they have in the past.
"We're already making big strides in California," he said. "I suspect if we repeated this two years from now, we'd see fewer disparities."
For more on healthcare, follow me on Twitter: @LATerynbrown