Anthropometry-based equations overestimate the urea distribution volume in hemodialysis patients

Kloppenburg, Wybe; Stegeman, Coen A.; Jong, Paul E. de; Huisman, Roel M.

doi:10.1046/j.1523-1755.2001.00603.x

Cited by 12 publications

(26 citation statements)

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“…Although previous studies have demonstrated that the Watson equation overestimates the TBW in HD patients (Table 4), 17 -21 a unique feature of our study is the comprehensive anthropometric assessments to help explain the reasons behind this finding. Lee et al developed equations in men and women to estimate TBW.…”

Section: Discussionmentioning

confidence: 76%

Volume Estimates in Chronic Hemodialysis Patients by the Watson Equation and Bioimpedance Spectroscopy and the Impact on the Kt/V_urea calculation

Noori

Wald

Parpia

et al. 2018

Can J Kidney Health Dis

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Background:Accurate assessment of total body water (TBW) is essential for the evaluation of dialysis adequacy (Kt/Vurea). The Watson formula, which is recommended for the calculation of TBW, was derived in healthy volunteers thereby leading to potentially inaccurate TBW estimates in maintenance hemodialysis recipients. Bioimpedance spectroscopy (BIS) may be a robust alternative for the measurement of TBW in hemodialysis recipients.Objectives:The primary objective of this study was to evaluate the accuracy of Watson formula–derived TBW estimates as compared with TBW measured with BIS. Second, we aimed to identify the anthropometric characteristics that are most likely to generate inaccuracy when using the Watson formula to calculate TBW. Finally, we derived novel anthropometric equations for the more accurate estimation of TBW.Design and Setting:This was a cross-sectional study of prevalent in-center HD patients at St Michael’s Hospital.Patients:One hundred eighty-four hemodialysis patients (109 men and 75 women) were evaluated in this study.Measurements:Anthropometric measurements including weight, height, waist circumference, midarm circumference, and 4-site skinfold (biceps, triceps, subscapular, and suprailiac) thickness were measured; fat mass was measured using the formula by Durnin and Womersley. We measured TBW by BIS using the Body Composition Monitor (Fresenius Medical Care, Bad Homburg, Germany).Methods:We used the Bland-Altman method to calculate the difference between the TBW derived from the Watson method and the BIS. To derive new equations for TBW estimation, Pearson’s correlation coefficients between BIS-TBW (the reference test) and other variables were examined. We used the least squares regression analysis to develop parsimonious equations to predict TBW.Results:TBW values based on the Watson method had a high correlation with BIS-TBW (correlation coefficients = 0.87 and P < .001). Despite the high correlation, the Watson formula overestimated TBW by 5.1 (4.5-5.8) liters and 3.8 (3.0-4.5) liters, in men and women, respectively. Higher fat mass and waist circumference (general and abdominal obesity) were correlated with the greater TBW overestimation by the Watson formula. We created separate equations for men and women based on weight and waist circumference.Limitations:The main limitation of our study was the lack of an external validation for our novel estimating equation. Furthermore, though BIS has been validated against traditional reference standards, our assumption that it represents the “gold standard” for body compartment assessment may be flawed.Conclusions:The Watson formula generally overestimates TBW in chronic dialysis recipients, particularly in patients with the highest waist circumference. Widespread reliance on the Watson formula for derivation of TBW may lead to the underestimation of Kt/Vurea..

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Section: Discussionmentioning

confidence: 76%

Volume Estimates in Chronic Hemodialysis Patients by the Watson Equation and Bioimpedance Spectroscopy and the Impact on the Kt/V_urea calculation

Noori

Wald

Parpia

et al. 2018

Can J Kidney Health Dis

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“…In this study, the DCTool corrected the spKt/V value from OCM from 1.21 AE 0.21 to 1.52 AE 0.22 (mean AE SD), and the SD of the difference between spKt/Vb and spKt/V OCM was substantially improved, showing a value of À0.02 AE 0.03 (mean AE SD). This again shows the importance of having a correct V in the dialysis dose calculations [15]. Figure 3A shows the sensitiveness of the UVabsorbance even when small disturbances caused by blood pump stops were present.…”

Section: Discussionmentioning

confidence: 85%

“…Anthropometry-based equations, e.g. the Watson formula, overestimate V in haemodialysis patients [15], which may give an underestimation of the Kt/V value. The OCM utilizes the Watson formula for the V calculation, which could explain the lower values obtained with OCM in case of readings of spKt/V, compared with spKt/V from blood.…”

Section: Discussionmentioning

confidence: 99%

Dialysis dose (Kt/V) and clearance variation sensitivity using measurement of ultraviolet-absorbance (on-line), blood urea, dialysate urea and ionic dialysance

Uhlin¹,

Fridolin²,

Magnusson³

et al. 2006

Nephrology Dialysis Transplantation

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“…Watson's formula is the most widespread anthropometry-based equation implemented in dialysis monitors for displaying on the dialysis monitor screen a direct estimation of (Kt/V) obtained from measurement of ionic dialysance. However Watson's formula overestimates V by 20% to 30% in comparison with the value V DDQ of urea distribution volume determined from direct dialysis quantification (DDQ), which is generally considered as the gold standard in hemodialysis patients but is unsuitable for clinical routine (12–17).…”

Section: Discussionmentioning

confidence: 99%

Ionic Dialysance and Determination of Kt/V in on-line Hemodiafiltration with Simultaneous Pre- and Post-dilution

2013

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Anthropometry-based equations overestimate the urea distribution volume in hemodialysis patients

Cited by 12 publications

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Volume Estimates in Chronic Hemodialysis Patients by the Watson Equation and Bioimpedance Spectroscopy and the Impact on the Kt/V_urea calculation

Volume Estimates in Chronic Hemodialysis Patients by the Watson Equation and Bioimpedance Spectroscopy and the Impact on the Kt/V_urea calculation

Dialysis dose (Kt/V) and clearance variation sensitivity using measurement of ultraviolet-absorbance (on-line), blood urea, dialysate urea and ionic dialysance

Ionic Dialysance and Determination of Kt/V in on-line Hemodiafiltration with Simultaneous Pre- and Post-dilution

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Anthropometry-based equations overestimate the urea distribution volume in hemodialysis patients

Cited by 12 publications

References 0 publications

Volume Estimates in Chronic Hemodialysis Patients by the Watson Equation and Bioimpedance Spectroscopy and the Impact on the Kt/Vurea calculation

Volume Estimates in Chronic Hemodialysis Patients by the Watson Equation and Bioimpedance Spectroscopy and the Impact on the Kt/Vurea calculation

Dialysis dose (Kt/V) and clearance variation sensitivity using measurement of ultraviolet-absorbance (on-line), blood urea, dialysate urea and ionic dialysance

Ionic Dialysance and Determination of Kt/V in on-line Hemodiafiltration with Simultaneous Pre- and Post-dilution

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Product

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Volume Estimates in Chronic Hemodialysis Patients by the Watson Equation and Bioimpedance Spectroscopy and the Impact on the Kt/V_urea calculation

Volume Estimates in Chronic Hemodialysis Patients by the Watson Equation and Bioimpedance Spectroscopy and the Impact on the Kt/V_urea calculation