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Mortality figures about diabetes and its comorbidities may be underreported by as much as 60% says the Centers for Disease Control and Prevention (CDC) in Atlanta. Despite the rapidly increasing incidence of diabetes in the United States, the reporting of diabetes as a cause of death or secondary cause of death on official documents actually decreased by 2% between 1986 and 1993, according to Frank Vinicor, MD, an epidemiologist and director of the CDC’s division of diabetes.
In a survey of death statistics nationwide, Vinicor and CDC researchers found that in 1993, diabetes was mentioned on the death certificates of only 36% of known diabetics who died that year. In 1986, the last survey found that diabetes was mentioned on 38% of all death certificates of known diabetics. It was listed as a comorbidity in 10% and as a contributing cause in 30%.
Vinicor says he doesn’t think the death rate is falling, but rather, the true rate is not accurately reflected in official documents. "In a sense, you don’t die of diabetes, but of its complications," says Vinicor, who suggests that those who fill out death certificates may not be properly trained to include information that will help reflect the true burden of the disease.
Sometimes researchers can trace a cause of death back to diabetes if it is listed as something unique to diabetes, such as certain types of kidney failure or amputations, he says. But with complications such as coronary artery disease or myocardial infarction or hypertension, "It is easy to put those causes of death on a death certificate and not list diabetes even as a contributing factor."
Because of its multiple comorbidities, he says, underreporting of diabetes deaths is far more likely than for other disease such as cancer, where "the cause of death is obvious. A diabetic may appear perfectly healthy and die of a heart attack tomorrow." Reflecting the true burden of diabetes is important in the effort to elicit more government funding for diabetes research to find a cure, says Vinicor.
Mortality statistics "serve as an important barometer of the impact of diabetes in our society," according to the CDC’s paper on underreporting presented at the American Diabetes Association’s scientific sessions in June.
"We think the underreporting is about 60%," says Vinicor, who says an increase in the burden of the disease would get more attention for diabetes funding. The National Institutes for Health (NIH), conduit for government funding for diabetes research, might sit up and take more notice if the mortality figures showed a greater burden of the disease, he speculates.
"Dr. [Frank] Varmus [the NIH director] has shown in his editorial in the New England Journal of Medicine that he feels there’s a lot of NIH research for diabetes already," Vinicor says.
Johns Hopkins researchers say the CDC’s findings on underreporting of mortality would make a difference in their findings that the burden of diabetes is adequately reflected in NIH funding levels.
"We only had available what is currently reported," says Neil R. Powe, MD, professor of medicine and epidemiology at the Johns Hopkins School of Public Health in Baltimore. "But differences of the magnitude Dr. Vinicor is talking about would make a difference." Powe’s team studied disability-adjusted life years to determine the burdens of 29 diseases on society in relationship to research funding levels. (One disability-adjusted life-year is defined as the loss of one year of healthy life due to disease.)
They concluded in their study published in the June 17 issue of the NEJM, "The acquired immunodeficiency syndrome, breast cancer, diabetes mellitus, and dementia all received relatively generous funding." In an editorial in the same issue, Varmus used the Johns Hopkins findings to support his statements that adequate research funding is provided for a variety of chronic diseases.
[For more information, contact Frank Vinicor at (770) 488-5000.]