New study suggests link between obesity and kidney disease in black men

April 23, 2013 in Family Medicine, Health, News, Statewide News, Top Stories

Special to The Mississippi Link

JACKSON – A study in Jackson-area African-Americans found a correlation between weight and chronic kidney disease in obese men but not in the same category of women.

Dr. Marino Bruce (Photo courtesy of UMMC)

“I kind of had a hunch about that,” said Dr. Marino Bruce, assistant professor of medicine and the study’s principal investigator. “So we designed a study that would pick up those differences if they existed.

“In a nutshell, the findings say we need to pay more attention to weight status in African-American men.”

Chronic kidney disease, or CKD, can progress to kidney failure and expensive measures, including medications, dialysis and transplantation. It’s a fast-growing problem in the U.S., particularly among African-Americans.

“Chronic kidney disease becomes a top 10 cause of death in African-American men at age 35 versus 55 for white men,” said Bruce, also a visiting associate professor of sociology and criminal justice at Jackson State University. “Clearly there’s earlier onset in African-American men and faster progression from chronic kidney disease to kidney failure.”

Trying to pinpoint the social, cultural, environmental and gender-based reasons why is what motivates Bruce. To get there, his study drilled down into an all-African-American group.

Using data collected in the Jackson Heart Study, Bruce and his research team separated 3,430 adults by gender into four BMI-based weight categories: normal, overweight, class I and class II obese. Of the entire group, 20 percent had CKD.

Men’s and women’s CKD percentages stayed fairly parallel across the first three weight categories. But the men’s percentage jumped from 19.4 in class I obese to 28.9 percent in class II obese. By comparison, the women’s CKD percentages in the same categories rose only from 20.1 to 25.3.

Still, for the entire group, CKD wasn’t associated with heavier weight. Parsing the numbers further, investigators found no clear pattern of associations between weight categories, CKD and various diseases that are major factors in CKD, including hypertension and diabetes.

“Some people have looked at our findings and said, ‘You’ve found nothing,’” Bruce said. ”But in actuality, our study tells us a lot about African-Americans.

“It means there are multiple dynamics – social, economic, educational, health status and so on – that interact to affect chronic kidney disease.”

Analysis turned up other incongruities. Significantly more low-income men were normal weight than any other weight category. And high-income men were more likely to be overweight or obese than their high-income female counterparts.

In education, the percentage of men with college degrees increased across increasing weight-status categories. Just the opposite trend occurred in women.

“At least in this sample, socioeconomic status does not offer the same buffer to obesity and chronic kidney disease as it does in other groups,” Bruce said.

The Journal of Investigative Medicine published the study this month. Bruce’s research team included investigators at the University of South Alabama, Vanderbilt University, the Wake Forest School of Medicine and Charles Drew University.

Funding for the research came from the National Heart, Lung and Blood Institute through a 5-year grant Bruce received while at Meharry Medical College in Nashville, Tenn. He came to Mississippi in 2010 to work more closely with the Jackson Heart Study.

The 13-year-old Jackson Heart Study tracks the health of 5,300 African-Americans in Mississippi’s capital region. Researchers use data gathered in JHS to examine a broad range of health, lifestyle and chronic disease topics.

JHS is a collaboration between UMMC, JSU and Tougaloo College. Dr. Herman Taylor, professor of cardiology and JHS’ principal investigator, said Bruce’s work can give insight into the complexities of health disparities.

“His is the kind of in-depth research we envisioned when setting up the Jackson Heart Study,” Taylor said. “Work like Dr. Bruce’s, which takes into account social and environmental factors, can help us understand the multiplicity of reasons why African-Americans face different, and often more difficult, health challenges than other groups.”

Bruce said he’d ultimately like to see his study’s findings applied in communities to help improve health.

“This study is about getting a clearer picture for the likelihood of this particular disease,” he said. “Knowing those risks by weight status, sex and other factors can help us get a clear focus on how social environment has an influence on behavior that has implications for health outcomes.”