The Effects of Racial Differences on Body Composition and Total Body Water Measured by Multifrequency Bioelectrical Impedance Analysis Influence Delivered Kt/V Dialysis Dosing

Abstract

Introduction: Haemodialysis dosing is traditionally based on urea clearance (Kt/V). Aiming for the same Kt/V target, some racial groups have better survival. We investigated whether body composition differs with ethnicity and may lead to differences in Kt/V delivered. Methods: We compared total body water (TBW) measured by multifrequency bioelectrical impedance analysis (MF-BIA) that calculated from standard anthropometric equations. Results: Three hundred and seventy-one adult patients, with a mean age of 58.2 ± 16.6 years, 60.6% of whom were male, 29.1% diabetic, 38.5% Caucasoid, 29.4% African/Afro-Caribbean, 24.8% South Asian and 5.4% East Asian, were studied. TBW measured by MF-BIA differed significantly from that predicted by anthropometric equations. Body fat of women and diabetics was greater, and muscle mass in South Asians was reduced. The difference between the TBW MF-BIA measurement and that of the equation by Watson et al. [11] was associated with % muscle mass (β -10.8, p < 0.001), age (β 0.23, p < 0.001), serum albumin (β -0.24, p < 0.001), body mass index (β 0.91, p = 0.001) and racial origin (β -9.86, p = 0.04). Conclusions: Variation in body composition between ethnic groups potentially leads to over-estimation of delivered dose for some ethnic groups and underestimation for others when using anthropometric equations. MF-BIA assessments of body water should be evaluated as a method for dosing dialysis patients.

Do Bioimpedance Measurements of Over-Hydration Accurately Reflect Post-Haemodialysis Weight Changes?

“…Previous studies on BIS have reported on Caucasoid and African-American HD patients [2,3,22], and we did have patients from other ethnic groups, and reports have suggested that some bioimpedance measurements may vary between ethnic groups, but not in terms of ECW status [23,24], and we also did not find any association with ethnicity.…”

Chapter 6 Adequacy of Haemodialysis in UK Adult Patients in 2016: National and Centre-specific Analyses

“…Of the two commonly used measures of dialyser urea clearance, the UK Renal Registry (UKRR) has historically reported the urea reduction ratio (URR), the percentage fall in serum urea following a mid-week dialysis session. Whilst the alternative Kt/V is a better method for measuring dialysis dose because it takes account of the size of a patient and urea removal by ultrafiltration, it requires data items not routinely collected by all UK renal centres [5][6]. URR is the most commonly used measure of urea clearance in dialysis centres in Europe in daily practice [7] and predicts minimum dialysis dose in the majority of patients consistently with Kt/V [8].…”

UK Renal Registry 19th Annual Report: Chapter 6 Adequacy of Haemodialysis in UK Adult Patients in 2015: National and Centre-specific Analyses

“…URR does not consider ultrafiltration or the size of the patient, and although Kt/V urea takes both into account, both URR and Kt/V urea can over-estimate dialyser urea clearance due to the rebound in serum urea concentration at the end of dialysis, particularly when higher blood pump speeds are used, and if blood sampling does follow approved protocols [2]. Whilst Kt/V provides a better estimate of urea clearance, it requires additional data items not routinely reported by most UK kidney dialysis centres [3,4]. As such, the UK Renal Registry (UKRR) has historically presented analyses based on URR rather than Kt/V urea for comparative audit of haemodialysis adequacy as these data are more readily available.…”