NEW YORK (Reuters Health) – Obesity is a strong risk factor for loss of residual kidney function after initiation of dialysis, according to new data from the prospective Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD).

Dr. Christiane Drechsler, from Leiden University Medical Center, and colleagues analyzed the effect of body mass index (BMI) on decline in kidney function and risk of anuria in 1271 patients starting dialysis treatment for the first time between 1997 and 2006.

The patients were grouped according to BMI determined at baseline (i.e., 3 months after the start of dialysis): BMI less than 20 kg/m2 (underweight); BMI 20 to 25 (normal weight); BMI 25 to 30 (overweight); or BMI 30 or greater (obese).

The mean age of the patients was 59 years, mean BMI was 24.8, and mean glomerular filtration rate (mGFR) was 4.7 mL/min.

In the June issue of the American Journal of Kidney Diseases, Dr. Drechsler and colleagues report that being overweight or obese significantly increased the decline in kidney function during the 18 months after the initiation of dialysis therapy, whereas being underweight did not.

Specifically, normal weight patients (reference) had a mean decrease in mGFR of 1.2 mL/min/year. Obese patients lost 1.2 mL/min more mGFR per year, “reflecting a 100% greater loss of residual kidney function per year compared with patients with normal weight,” the investigators point out.

Compared to normal weight patients, overweight patients lost 0.4 mL/min more mGFR per year, whereas underweight patients lost 0.6 mL/min less mGFR per year.

The adjusted relative risk of anuria was similar among BMI groups; a total of 297 patients developed anuria during the study period.

“Future interventional studies are required to show whether obese dialysis patients might benefit from a healthy weight reduction,” Dr. Drechsler and colleagues conclude.

Reference:
Am J Kidney Dis 2009;53:1014-1023.