Prevalence of kidney stones doubles in wake of obesity epidemic

The number of Americans suffering from kidney stones between 2007 and 2010 nearly doubled from 1994, according to a new study by researchers at UCLA and the RAND Corp.

“While we expected the prevalence of kidney stones to increase, the size of the increase was surprising,” said Dr. Charles D. Scales Jr., a Robert Wood Johnson Foundation/U.S. Department of Veterans Affairs Clinical Scholar in the departments of urology and medicine at the David Geffen School of Medicine at UCLA. “Our findings also suggested that the increase is due, in large part, to the increase in obesity and diabetes among Americans.”

The study, “The Prevalence of Kidney Stones in the United States” is being presented today at the 2012 meeting of the American Urological Association in Atlanta, Ga., and will appear in the July print edition of the peer-reviewed journal European Urology.

This is one of the first studies to examine new data from the National Health and Nutrition Examination Survey (NHANES) that was collected from 2007 to 2010. NHANES is a program of studies within the Centers for Disease Control and Prevention to assess the health and nutritional status of adults and children in the U.S.

Scales and his colleagues reviewed responses from 12,110 individuals and found that between 2007 and 2010, 8.8 percent of the U.S. population had a kidney stone — one out of every 11 people. In 1994, the rate was one in 20. (No data about the national prevalence of kidney stones in the U.S. were collected between 1994 and 2007.)

Because NHANES also asks about other health conditions and includes measurements of height and weight, the researchers were able to identify associations between kidney stones and other health conditions. The results suggest that obesity, diabetes and gout all increase the risk of kidney stones.

While the national obesity rate was 23 percent in 1994, more than a third of all American adults are obese today, according to the Centers for Disease Control and Prevention.

The authors assert that these findings have important implications for the public, as well as health care providers.

“People should consider the increased risk of kidney stones as another reason to maintain a healthy lifestyle and body weight,” said the study’s senior author, Dr. Christopher S. Saigal, principal investigator within RAND Health for the Urologic Diseases in America project and associate professor of urology at the David Geffen School of Medicine at UCLA. “But physicians need to rethink how to treat and, more importantly, prevent kidney stones.”

Currently, the primary approach to treating patients is to focus on those who already are suffering from kidney stones. Yet helping patients maintain a healthy diet and body weight can reduce the number of patients with kidney stones.

“Imagine that we only treated people with heart disease when they had chest pain or heart attacks and did not help manage risk factors like smoking, high cholesterol or high blood pressure,” Scales said. “This is how we currently treat people with kidney stones. We know the risk factors for kidney stones, but treatment is directed towards patients with stones that cause pain, infection or blockage of a kidney rather than helping patients to prevent kidney stones in the first place.”

In an accompanying editorial that will also appear in the journal, Dr. Brian Matlaga, associate professor of urology at Johns Hopkins University School of Medicine, writes that the cost of care for this disease is enormous, and there is no indication that the coming years will see any improvement in this trend. He also warns that, since approximately 10 percent of the population has kidney stones, a greater emphasis on prevention is imperative.

The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases (N01-DK70003), as part of the Urologic Diseases in America project based at UCLA and RAND.

The Robert Wood Johnson Foundation Clinical Scholars program has fostered the development of physicians who are leading the transformation of health care in the United States through positions in academic medicine, public health and other leadership roles. Through the program, future leaders learn to conduct innovative research and work with communities, organizations, practitioners and policymakers on issues important to the health and well-being of all Americans. This program is supported, in part, through collaboration with the U.S. Department of Veterans Affairs.

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