"Our results confirm an accumulating body of clinical and experimental data implicating obesity as an important causative factor in kidney disease," comments Dr. Elisabeth Ejerblad of Uppsala University, Sweden, lead author of the new study.
Dr. Ejerblad and colleagues assessed body mass index (BMI)—a measure of weight that considers the person's height—and other potential risk factors in 926 Swedish patients with moderately severe CRF. Chronic renal failure is gradual, irreversible loss of kidney function that can lead to end-stage renal disease (ESRD), a permanent loss of kidney function requiring dialysis or kidney transplantation. Nine hundred ninety-eight persons with normal kidney function were studied for comparison.
Obesity—defined as a BMI of 30 or higher—was a strong risk factor for CRF. Subjects who met the definition of obesity at any age were three to four times more likely to develop CRF. For women, morbid obesity—BMI 35 or higher—was also a risk factor for CRF.Risk was also increased for people who fell short of the study definition of obesity but were still overweight. Risk of CRF was tripled for both men and women who were overweight—BMI 25 or higher—at age 20 or later.
The link between obesity and CRF was strongest for diabetes-related kidney disease. However, for all subtypes, obesity doubled or tripled the risk of CRF. Even for people who had neither high blood pressure nor diabetes—both risk factors for kidney disease—being overweight at age 20 or older tripled the risk of CRF.
"Chronic renal failure is an escalating health problem throughout the world," says Dr. Ejerblad. "Because of the high rates of ESRD and death, it is of the utmost importance to identify potentially preventable causes or CRF." Rates of both obesity and CRF have risen rapidly in recent years but few studies have looked at the possible relationship between the two.
"Our study confirms an accumulating body of clinical and experimental data implicating obesity as a significant but preventable risk factor for chronic renal failure," Dr. Ejerblad adds. "Based on our findings, we estimate that obesity causes 15 percent of CRF in men and 11 percent in women. The excess risk for CRF among obese people appears mainly to be driven by a high prevalence of hypertension and/or type II diabetes, but additional pathways cannot be ruled out."
The article, entitled "Obesity and Risk of Chronic Renal Failure" will appear in print in the June issue of the Journal of the American Society of Nephrology.