Overweight and obese teens are more likely to develop renal failure later in life, a population-based study from Israel showed.
Overweight at age 17 was associated with a three-fold elevated incidence of end-stage renal disease over the subsequent 25 years, Asaf Vivante, MD, of the Israeli Defense Forces Medical Corps and Safra Children’s Hospital in Tel Hashomer, Israel, and colleagues reported
Obese teens were at nearly seven-fold risk after similar adjustment for sex, blood pressure, and other variables, they reported online in the Archives of Internal Medicine.
“While this association does not prove causation, the finding highlights another possible benefit in the urgent need to address childhood and adolescent obesity as a possible modifiable risk factor,” they wrote.
The association was seen both in relation to diabetes and without it, which “adds end-stage renal disease to the list of adverse outcomes associated with adolescent overweight and obesity,” noted an accompanying invited commentary.
That’s both good and bad news, since obesity is a potentially modifiable risk factor but difficult to address, explained commentator Kirsten L. Johansen, MD, of the San Francisco VA Medical Center.
“Although there is no evidence that it is ever too late to improve outcomes by increasing physical activity or shedding excess weight,” she wrote, “the results reported … highlight the potential advantages of starting early before chronic disease has developed and unhealthy lifestyles have become lifelong habits.”
The study crosslinked medical data collected through universal, mandatory screening of all 17-year-olds for military service in Israel with a national end-stage renal disease registry there.
Individuals with any proteinuria or hematuria on urinalysis or diagnosis related to kidney disease found in the thorough medical history at baseline were excluded from the analysis.
The remaining 1.2 million individuals with 25 years of follow-up available through the databases could thus be ruled out as having pre-existing subclinical kidney disease.
The overall incidence of treated end-stage renal disease over 25 years was 2.87 cases per 100,000 person-years.
For adolescents in the overweight category with a body mass index in the 85th to 95th percentile, that rate went up to 6.08 per 100,000 person-years.
It was 13.40 per 100,000 person-years for teens with a BMI in or above the 95th percentile indicating obesity.
After multivariate adjustment for sex, country of origin, systolic blood pressure, and period of enrollment, the hazard ratio for treated end-stage renal disease from any cause was:
3.00 for overweight teens (95% confidence interval 2.50 to 3.60)
6.89 for obese teens (95% CI 5.52 to 8.59)
“Elevated BMI constitutes a substantial risk factor for diabetic and nondiabetic ESRD,” the researchers concluded.
They attempted to get at mechanisms, too, looking specifically at cause of the disease as recorded by the nephrologist at initiation of dialysis.
As expected, there were strong, independent associations between diabetic end-stage renal disease and adolescent BMI:
5.96-fold elevated risk for overweight teens (95% CI 4.41 to 8.06)
19.37-fold elevated risk for obese teens (95% CI 14.13 to 26.55)
However, end-stage renal disease not related to diabetes was also a bigger risk for these individuals than for those who had a BMI in the normal range as teens:
2.17-fold elevated risk for overweight teens (95% CI 1.71 to 2.74)
3.41-fold elevated risk for obese teens (95% CI 2.42 to 4.79)
A link between weight and kidney failure independent of diabetes is plausible, Vivante’s group explained.
Possible mechanisms “include leptin-related renal fibrosis, elevated plasma renin and aldosterone levels, and presumed preceding underlying obesity-associated focal segmental glomerulosclerosis, renal hyperperfusion, and hyperfiltration,” they noted.
The researchers cautioned, though, that weight and height were measured only once, in the teen years, without follow-up data available for change.
Other limitations were lack of glomerular filtration rate data at enrollment that would point to asymptomatic or undetected early-stage chronic kidney disease, though rare in teens, and possibly limited generalizability to non-Jewish populations.
Access to anonymized databases for the analysis was provided by the Israeli Defense Forces Medical Corps and the Israeli Ministry of Health.
The researchers reported having no conflicts of interest to disclose.
Johansen reported having no conflicts of interest to disclose.
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Primary source: Archives of Internal Medicine
Source reference: Vivante A, et al “Index in 1.2 million adolescents and risk for end-stage renal disease” Arch Intern Med 2012; DOI: 10.1001/2013.jamainternmed.85.
Additional source: Archives of Internal Medicine
Source reference: Johansen KL “The skinny on obesity and end-stage renal disease” Arch Intern Med 2012; DOI: 10.1001/2013.jamainternmed.917.
