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Kidney Risk Determined Early in Life

May 3, 2011

Lifestyle decisions made before age 30 appear to determine a person’s risk of developing chronic kidney disease many years down the road….

Individuals who neglected to eat a quality diet — defined as the National Heart, Lung and Blood Institute’s DASH (Dietary Approaches to Stop Hypertension) diet — had a 63% increased risk of chronic kidney disease 20 years later than did participants in the study who ate a diet rich in fruits and vegetables and low in fat (P<0.05).

“Unhealthy lifestyle behaviors such as eating a poor-quality diet, smoking, and being obese may increase the risk of early kidney disease,” said Alexander Chang, MD, a fellow in nephrology at the Loyola University Medical Center in Maywood, Ill., at his poster presentation at the National Kidney Foundation Spring Clinical Meetings.

In the study, Chang and colleagues reviewed the health records of 5,112 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. The researchers identified 97 participants who developed microalbuminuria during the 20-year follow-up.

The development of hypertension by year 15 resulted in a fourfold risk of kidney disease by year 20 (P<0.001) and the development of diabetes by year 15 resulted in a nine-fold risk of kidney disease by year 20 (P<0.001).

Because the development of diabetes and hypertension likely occurred due to obesity, by year 20, obesity was not a statistically significant cause of kidney disease in the multivariate analysis. Chang also mentioned that smoking, while associated with an increased risk, did not reach statistical significance for kidney disease in the multivariate analysis.

“By the time we are seeing patients it is already too late,” he said. “They already have diabetes or hypertension or both, and a lot of them happen to be very obese.”

Chang said the cohort was somewhat unique: the subjects were recruited when they were 18 to 30 years of age and before they had diabetes, high blood pressure, or other diseases. The researchers stratified the group on the basis of a diet score based on the DASH diet. “What we found is that the risk of kidney disease among people who eat what doesn’t look at all like a DASH diet is about twice the risk as someone who eats a diet that resembles a DASH diet. Smoking gives you a 50% increase in risk; if you look at obesity, you have a nearly threefold increase in risk,” Chang said.

“If you look at the number of lifestyle factors — smoking, little activity, poor diet, and obesity, the risk of kidney disease increases with every unhealthy lifestyle habit you have.” He demonstrated that one risk factor doubles the risk of kidney disease (P<0.05), two risk factors triple the risk (P<0.01), and three to four risk factors increase the likelihood more than fourfold (P<0.01).

“The thing about lifestyle factors is that they can affect other disease processes that affect kidney disease,” said Michael J. Choi, associate professor of nephrology at Johns Hopkins School of Medicine, and scientific program chairman for the meeting.

“In the DASH diet, we really try to have a push on fruits, vegetables. There is some thought that there is potassium in fruits and vegetables. There is citrate which is a base that may help fight acid loads. We can see how diet can be very helpful.”

“Obesity is bad for everything — heart disease, hypertension, metabolic syndrome, cholesterol,” he said in commenting on the study. “All those things could exacerbate any predisposition you have for kidney disease — and probably is an additive factor as well.”

“Although these factors have been shown to increase cardiovascular and other disease risks, this study is the first to show that [they] also increase the risk of kidney disease,” Chang said.

“To me this is really important because when I am seeing patients in clinic, usually the number one question I am asked is ‘Doctor, what can I do to improve my health without taking medications?’ ” he said.

“Everything your mom told you that [is] good for you [is] probably good for you. That’s kind of the gist of it,” Chang said. “If you want to make changes to impact kidney disease, it should be done early in life.”

Practice Pearls

  • Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
  • Point out that in this study, dietary factors in young adults were associated with an increased incidence of chronic kidney disease 20 years later.

Chang A, et al “Lifestyle behaviors and incident chronic kidney disease: The CARDIA study” NKF 2011 Spring Clinical Meetings; Abstract 61.