Nutritional assessment of continuous ambulatory peritoneal dialysis patients by bioelectrical impedance

The Dialysis Outcomes Quality Initiative (DOQI) guidelines suggest that anthropometric measurements are useful in assessment of nutrition. However, the technique is operator-dependent and time consuming. To estimate fat-free mass and fat mass, bioelectrical impedance analysis (BIA) measures the impedance of an electrical current passing through the body. Our aim in the present study was to validate the use of BIA in continuous ambulatory peritoneal dialysis (CAPD) patients.

We recruited patients from the CAPD clinic. The biceps, triceps, subscapular, and suprailiac skinfold thickness were measured by Harpenden skinfold calipers (British Indicators, Burgess Hill, West Sussex, U.K.). Using a linear regression equation (Durin and Womersley) and the Siri equation, we calculated percentage body fat composition from the anthropometric measurements. For BIA assessment, fat composition was measured using the Body Composition Analyzer (TBF-300GS: Tanita Corporation of America, Arlington Heights, IL, U.S.A.).

We recruited a total of 60 patients who had been on CAPD for 21.8 +/- 23 months. The percentage of body fat in the study group as estimated by anthropometry was 27.5% +/- 8.6% (range: 5.78% - 40.4%). By BIA, the percentage of body fat was 17.6% +/- 8.9% (range: 2.4% - 42.3%). The results by the two methods were highly correlated (r = 0.712, p < 0.001). By paired t-test, the mean difference in body fat composition using the two different methods was 9.9% +/- 6.6% (p < 0.001).

Measurement of body fat composition in CAPD patients by BIA and by anthropometry were highly correlated. The body fat composition measured by BIA was lower than that measured by anthropometry. The BIA method is simple and noninvasive. It may play a role in monitoring trend of body composition in CAPD patients in an outpatient setting.