Very Low Body Fat Linked to Higher Risk of Death in Dialysis Patients

Dialysis patients with low body fat are at increased risk of death, even compared to patients at the highest level of body fat percentage, claims a new study.

Researchers at the Los Angeles Biomedical Research Institute (LABioMed; CA, USA) used near-infrared interactance technology to measured body fat percentage in 671 hemodialysis patients from eight California (USA) dialysis centers. They then compared five-year mortality rates for patients at different levels of body fat percentage. The researchers found that mortality rate was highest for dialysis patients with less than 10% body fat, which was 2.5-3 times higher than for those with body fat of 20 to 30%. The increased risk of death for patients with very low body fat remained after adjustment for age, sex, race, other illnesses, and key laboratory results. Further analyses using continuous values of body fat (rather than categories) confirmed a direct, linear relationship between body fat and mortality risk. The study was presented at the annual meeting American Society of Nephrology, held during November 2009 in San Diego (CA, USA).

"The results add to the increasing number of reports about the 'obesity paradox' or 'reverse epidemiology' in patients with chronic kidney disease and other chronic diseases,” said Kamyar Kalantar-Zadeh, Ph.D., of LABioMed. "Counter-intuitively, higher body mass index is associated with greater survival in hemodialysis patients.”

Reverse epidemiology, a term coined by Dr. Kalantar-Zadeh in 2003, refers to a medical hypothesis which holds that obesity and high cholesterol may be protective and associated with greater survival in certain groups of people, such as very elderly individuals or those with certain chronic diseases. It further postulates that normal to low body mass index (BMI), or normal values of cholesterol may be detrimental and associated with higher mortality in asymptomatic people.

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Los Angeles Biomedical Research Institute