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Lower Body Fat Is a Strong Predictor of Mortality in Patients on Haemodialysis: Presented at Renal Week 2009

By Kristina Rebelo

SAN DIEGO -- November 2, 2009 -- Patients on dialysis who have a lower body-fat percentage are at an increased risk of death compared with their heaviest counterparts who are at the highest level of body-fat percentage, even after adjustment for all other surrogates of nutritional status, according to a study presented here at the at the American Society of Nephrology (ASN) Renal Week 2009.

"Our study indicates that body fat may be protective in dialysis patients," said Kamyar Kalantar-Zadeh, MD, LABioMed at Harbor-University of California, Los Angeles, Torrance, California, at a presentation on October 30.

"The results add to the increasing number of reports about the so-called 'obesity paradox' or 'reverse epidemiology' in patients with chronic kidney disease and other chronic diseases. Counter intuitively, higher body-mass index is associated with greater survival in haemodialysis patients."

Using near-infrared interactance, the researchers measure body-fat percentage in 671 patients on haemodialysis. They then compared 5-year mortality rates for patients at different levels of body-fat percentage.

Patients were divided onto 5 groups: those with <10% body fat (n = 34); patients with 10% to <20% body fat (n = 156); 20% to <30% body fat (n = 210); 30% to <40% body fat (n = 182); and patients with >=40% body fat (n = 89).

Results showed that patients with the lowest body fat (<10%) had a 2.5 to 3 times higher risk of death compared with patients who had 20% to 30% body fat, after adjustment for factors such as age, gender, race, diabetes, and Charlson index score.

"The higher the body fat, the greater the survival," noted Dr. Kalantar-Zadeh, after further analyses using continuous values of the body fat confirmed a direct, linear relationship between body fat and mortality risk.

Study limitations were that it was an observational study and that subcutaneous fat of the upper arm was estimated, which could be different from the intra-abdominal fat.

At the ASN briefing, presenter and co-author Debbie Benner, MS, RD, DaVita, Lakewood, Colorado, said that dialysis patients need to be counselled about appropriate weight-to-height levels.

"When patients eat, they have to eat quality protein and restrict salt, which is the key part to making calories count," she said. "If a patient is too thin, they could end up with another disease and have no reserves."

Funding for this study was provided by the National Institutes of Health.

[Presentation title: Association of Body Fat and Survival in Hemodialysis Patients. Abstract SA-PO2567]

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