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Recommendations Summary

CKD: Nutrition Assessment: Body Composition with Bioelectrical Impedance (BIA) and Dual-Energy X-Ray Absorptiometry (DEXA) (2020)

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.


  • Recommendation(s)

    CKD: Bioelectrical Impedance for Patients on Maintenance Hemodialysis (MHD)

    In adults with CKD 5D on MHD, we suggest using bioimpedance and preferably multi-frequency bioelectrical impedance (MF-BIA) to assess body composition when available. Bioimpedance assessments should ideally be performed a minimum of 30 minutes or more after the end of the hemodialysis session to allow for redistribution of body fluids (2C).

    Rating: Weak
    Conditional

    CKD: Bioelectrical Impedance for Patients, Non-Dialyzed and on Peritoneal Dialysis (PD)

    In adults with CKD 1-5 or CKD 5D on PD, there is insufficient evidence to suggest using bioelectrical impedance to assess body composition (2D).

    Rating: Weak
    Conditional

    CKD: Dual-Energy X-Ray Absorptiometry (DXA) for Body Composition Assessment

    In adults with CKD 1-5D or posttransplantation, it is reasonable to use DXA when feasible as it remains the gold standard for measuring body composition despite being influenced by volume status (OPINION).

    Rating: Consensus
    Conditional

    • Risks/Harms of Implementing This Recommendation

      There are no obvious risks or harms associated with these recommendations.

    • Conditions of Application

      Special Discussions
      The guidelines for multi-frequency bio-electrical impedance analysis (MF-BIA), dual-energy x-ray absorptiometry (DEXA), skinfold measurements, and waist circumference require specialized equipment.  Good quality calipers are needed to obtain an accurate measurement of skinfold thickness.  However, the measurer must be trained in order to obtain accurate results. To obtain waist circumference, only a measuring tape is required.  Once again, the measurer must be trained on how to obtain this measure. MF-BIA is becoming more widely available as the technology advances.  However, training is needed to understand and to appropriately interpret the output from the device.

      Implementation Considerations

      MF-BIA

      • The guideline for MF-BIA applies to all adult patients receiving MHD.  The measure must be obtained post-dialysis on a non-conducting surface for an accurate assessment.
      • When bioimpedance is performed in patients on PD, measurements should be done with an empty abdominal cavity (following PD fluid drainage) and bladder. For individuals on MHD with residual kidney functio, bladder should be empty.
      • There are no potential risks or harms associated with the application of the guideline for MF-BIA in adult patients receiving MHD. 

      Dual Energy X-ray Absorptiometry

      • DEXA is a valid technique for measuring body composition in adult CKD patients, including post-transplant patients. In MHD and PD patients, this is despite the measurement being influenced by over-hydration.
      • DEXA is associated with very small amounts of radiation and this should be considered when weighing benefits and risks of this method for a particular individual. Ten screenings with DEXA results in a similar amount of radiation exposure as one chest x-ray.

    • Potential Costs Associated with Application

      The guidelines for MF-BIA, DEXA, skinfold measurements, and waist circumference require specialized equipment. Because of the cost associated with some of these measures (e.g., MF-BIA, DEXA), there is insufficient evidence for the workgroup to suggest the use of these measurements on a routine basis in clinical practice.

    • Recommendation Narrative

      Body composition is an important factor in nutrition assessment in CKD. Dual-energy X-ray absorptiometry (DEXA) is a direct method that is considered the gold standard for assessing body composition in patients with CKD; however, this measure is labor intensive, invasive, expensive and can be influenced by a number of CKD related factors such as hydration status.

      Timing of body composition assessments is important in CKD since assumptions of hydration are required for accurate interpretation of the results, and fluid/electrolyte balance is likely to be altered significantly in CKD patients.  For these reasons, in adults undergoing dialysis, assessments are best obtained after treatment when body fluid levels are balanced (Carrero et al 2015 and Chumlea et al 2008).

      Regardless of the method selected to assess body composition, none are perfect, and the errors surrounding them should not be ignored.  Errors may have clinical relevance, especially if the individual is treated and observed over time (Chumlea et al 2008). Moreover, the results of the measures are only as useful as the availability of suitable reference data from a group of persons of at least the same age, race, gender and disease status.

      Multi-Frequency Bioelectrical Impedance Analysis (MF-BIA)
      Twelve studies reported on the use of MF-BIA to assess fat mass (FM) and fat free mass (FFM) in MHD, PD and pre-dialysis patients.  Four of these studies were validity/reliability studies: two in MHD patients (Donadio et al 2008, Furstenberg et al 2011); one in PD patients (Konings et al 2003); and one in pre-dialysis patients (Rigalleau et al 2004).  Three were prediction studies:  two in MHD patients, and one in MHD and PD patients (Abad et al 2011, Fiedler et al 2009, Rosenberger et al 2014).  Eight were correlation studies; five in MHD patients (Donadio et al 2008, Furstenberg et al 2011, Konings et al 2003, Mancini et al 2003, Ohanshi et al 2013, Rodrigues et al 2012, Cheng et al 2000); one in PD patients; one in MHD and PD patients (Nakao et al 2007); and one in pre-dialysis patients (Rigalleau et al 2004).

      MHD Patients 
      FM and FFM measured by MF-BIA had good agreement with DEXA in two studies (Donadio et al 2008, Furstenberg et al 2011),  had high correlations with several markers of nutritional status in four studies (Donadio et al 2008, Ohashi et al 2013, Rodrigues et al 2012, Nakao et al 2007) and predicted hard outcomes in three studies (Abad et al 2011, Fiedler et al 2009, Rosenberger et al 2014). Furstenburg, et al. concluded that MF-BIA was a more robust tool than DEXA for measuring body composition in MHD patients. Donadio, et al. found that MF-BIA yielded a smaller prediction error in MHD patients.

      Body composition determined by MF-BIA was found to be predictive of hospitalization (Fiedler et al 2009) and survival (Abad et al 2011, Fiedler et al 2009, Rosenberger et al 2014). In Rodriguez et al., BIA underestimated FM and overestimated FFM when compared with air displacement plethysmography in MHD patients.  PEW determined by MF-BIA was positively related to BMI and negatively associated with serum albumin level (Ohashi et al 2013). In Mancini, et al., bioimpedance vector analysis (BIVA) was predicted by normalized protein catabolic rate (nPCR) and albumin in MHD patients with normal nutritional status, but the predictive effects were not accurate in undernourished patients. In MHD patients, a body protein index score calculated from MF-BIA protein mass and height significantly correlated with blood protein levels in men on MHD, but there was no relationship in women on MHD (Nakao et al 2007).

      PD Patients 
      FM and FFM measured by MF-BIA showed wide limits of agreement with DEXA in 1 study, which was affected by hydration status (Konings et al 2003),  and was an independent risk factor for survival in another study Abad et al 2011).  In CAPD patients, LBM measured by MF-BIA and creatinine kinetic method were highly correlated but there was no difference in LBM using BIA in patients with or without peritoneal dialysate (Cheng et al 2000). A body protein index score calculated from MF-BIA protein mass and height significantly correlated with blood protein levels in men on MHD, but there was no relationship in women on MHD or CAPD patients. The findings varied according to sex and dialysis treatment (Nakao et al 2007).

      Pre-Dialysis Patients 
      In diabetic patients, % LBM measured by DEXA was greater than that predicted by BIA (p<0.05). Bland & Altman analysis demonstrated biases by BIA, but the mean of the results obtained by combined anthropometry and BIA demonstrated no bias from DEXA measurements (Rigalleau et al 2004).

      Near Infrared (NIR)
      Evidence examining the validity of NIR as a measure of body composition was too limited to make recommendations. 

    • Recommendation Strength Rationale

      The evidence supporting these recommendations is based on Grades III/Grade C,  D evidence as well as Consensus/expert opinion. 

    • Minority Opinions

      Consensus reached.