Subclinical versus overt obesity in dialysis patients: More than meets the eye

Abstract

Background. Obesity is an important problem in the epidemic of chronic kidney disease (CKD). Obesity is usually diagnosed by body mass index (BMI), but this metric has limitations as a measure of adiposity in CKD patients. Simple anthropometric tools, like skinfold thickness measurements, have been shown to be a better test to classify obesity among those with CKD.Methods. The prevalence of obesity was estimated by BMI (>30 kg/m2) and by skinfold thickness-estimated body fat (>25% in men and 35% in women) in two cohorts comprising 284 incident dialysis and 209 prevalent haemodialysis (HD) patients from Sweden. Patient characteristics were compared among individuals with differing diagnosis. Results. BMI obesity cut-offs misdiagnosed many patients (>50%) with excess adiposity. Obesity, estimated by BMI, was present in 9 and 10% of incident and prevalent dialysis patients, respectively. When estimated by percentage of body fat, the prevalence of obesity rose to 64 and 65%. In both cohorts, a large proportion of patients (55%) were obese in the context of a normal BMI (termed as subclinical obesity}. These individuals were older, presented more co-morbidity and lower surrogates of muscle mass [handgrip strength, arm muscle circumference or insulin-growth factor (IGF)-1 levels] than those diagnosed by both methods (termed overt obesity).Conclusion. A BMI of <30 kg/m2 does not exclude the presence of excess adiposity. Subclinical obesity is a frequent condition in dialysis patients, and the clinical consequences of this finding deserve further consideration. © The Author 2013. Published by Oxford University Press on behalf of ERAEDTA. All rights reserved.