Obese teens face higher risk for kidney disease: study

If, however, they lose weight their chances may be lowered, experts say.

"This study comes as close as one can to predicting that losing weight can reduce the risk of kidney disease," said Dr. Kirsten Johansen, a professor in the division of nephrology at the University of California, San Francisco.

Johansen, who wrote an accompanying editorial with the study, said that "this gives us one more reason we need to address childhood obesity and overweight, but it's hard to do."

There isn't an easy solution to the obesity epidemic, but if it can be halted, fewer people will develop heart disease, kidney disease and diabetes, she said.

Johansen, however, is optimistic. "The rate of obesity and overweight has gone up quickly in our kids. If we can turn this around, it could go down quickly as well," she said. "I'm not saying it's easy. It's easier to get kids to drink soda than eat vegetables."

The report was published online Oct. 29 in the Archives of Internal Medicine.

For the study, a team led by Dr. Asaf Vivante, of the Edmond and Lily Safra Children's Hospital, Sheba Medical Center in Tel Hashomer, collected data on almost 1.2 million 17-year-olds who were examined before service in the Israeli military between January 1967 and December 1997. The researchers then linked these teens to the Israeli end-stage kidney disease registry.

Over 30 years of follow-up, they found more than 700 men and 160 women developed end-stage kidney disease.

Vivante's group estimated being overweight or obese and being treated for diabetes increased the risk of developing end-stage kidney disease. The risk was increased sixfold for those who were overweight and 19 times for those who were obese, the researchers reported.

They noted, as expected, the risk for kidney disease was significant for those who were diabetic. However, the risk was also significant for those who didn't have diabetes.

"Although the results for diabetic [end-stage kidney disease] were remarkable, with risks increasing sixfold and 19-fold among overweight and obese adolescents, respectively, our results also indicate a substantial association between elevated BMI and nondiabetic, end-stage renal disease," the authors wrote in the report. BMI, or body mass index, is a measurement that takes into account height and weight.

This was a study of association and can't really prove that overweight and obesity cause kidney failure, said Dr. David Katz, director of the Yale University Prevention Research Center, who was not involved with the study.

"Other factors related to lifestyle and/or environment might be the reason for both obesity and kidney failure," he said.

In this case, the findings suggest obesity is an important risk factor for end-stage kidney disease and that much of this may be accounted for by diabetes, for which obesity is a well-established risk factor, and which, in turn, is a major cause of kidney disease, Katz said.

"But, the study also indicates that obesity may lead to kidney failure even when diabetes does not develop," he added.

"I'm not sure we really need yet another reason to recognize epidemic obesity as an enormous threat to human health, and an enormous cost center. But this study suggests we have one," Katz said.

Another expert, Nancy Copperman, director of public health initiatives in the Office of Community Health at North Shore-LIJ Health System in Great Neck, N.Y., said that "obesity is not cosmetic."

"Obesity has health consequences," she added. "We need to take it seriously."

More information: For more on obesity, visit the U.S. National Library of Medicine.

Journal reference: JAMA Internal Medicine

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