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/m(2)) 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/m(2) 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.
Keywords: anthropometrics; fatness; muscle; protein-energy wasting; sarcopenia.