EAL

CKD: Measuring Body Composition (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare predicted percentage of lean body mass (LBM) to DEXA measurements in non-diabetic uremic, non-uremic diabetic and uremic diabetic subjects
To measure percentage of LBM by anthropometry and bioimpedance (BIA) compared to DEXA in diabetic subjects with a wide range of renal disease
To evaluate whether the lowering of glomerular filtration rate (GFR) in diabetics patients was associated with an altered body composition as assessed by previous methods.

Inclusion Criteria:

Diabetic patients with renal disease with plasma creatinine more than 150umol per L and proteinuria greater than 0.5g per 24 hours.

Exclusion Criteria:

Not meeting the inclusion criteria.

Description of Study Protocol:

Design

Cross-sectional study.

Statistical Analysis

Paired and unpaired T-test
Regression analysis
Bland & Altman
Correlation coefficient.

Data Collection Summary:

Timing of Measurements

One-time measurement.

Dependent Variables

Body composition (LBM): The theoretical body composition was predicted from BMI, gender and age, according to Deurenberg.

Independent Variables

Anthropometry method: Four skinfold thickness measurements at bicipital, tricipital, subscapular and suprailiac sites
Bio-impedance method
DEXA (Biphotonic absorptiometry) method: Performed using a fanbeam model QDR-4500A-DEXA
GFR measured with Cr EDTA clearance.

Control Variables

Age
Hydration status.

Description of Actual Data Sample:

Initial N: 49 (35 males, 14 females)
Attrition (final N): 49 (35 males, 14 females)
Age: Mean age was 64 years old.

Other Relevant Demographics

GFR ranged from 8.0 to 89.0ml per minute per 1.73m². Non-uremic diabetic patients (61.1±15.1ml per minute per 1.73m²) had significantly greater clearance of creatinine compared to uremic non-diabetic patients (11.8±4.1ml per minute per 1.73m²). None of the subjects were treated by dialysis.

Anthropometrics

Age, gender and BMI were matched in the three groups (diabetic, diabetic uremic, non-diabetic uremic). However, no data were reported for the main group of diabetics (with 49 subjects) who were evaluated for comparison of different methods.

Location

Bordeaux, France.

Summary of Results:

Test comparisons	Population	N Pair	Linear Regression Analysis	Bland-Altman Limit of Agreement (LOA) Analysis
Test comparisons	Population	N Pair	Slope (R)	Mean Bias	Lower LOA (Lower CI)	Upper LOA (Upper CI)
LBM (kg) by DEXA, mean BIA and anthropometry	Diabetic CKD patients	49	0.94	+0.15	~6.5	6.5
LBM (kg) by DEXA vs antropometry	Diabetic CKD patients	49	0.9	+1.7		9.6
LBM (kg) by DEXA and BIA	Diabetic CKD patients	49	0.92	-1.5		7.8

Other Findings

LBM percentage measured by anthropometry and BIA were both well correlated with DEXA results; R=0.90 and R=0.92, respectively. However, the results obtained by both anthropometry and BIA differed from DEXA measurements, P<0.05
As compared to DEXA (percentage LBM was 69.0±7.1%), measurement of percentage of LBM by anthropometry (71.4±8.0%; P<0.05) and BIA (67.2±7.6%; P<0.05) were biased in 49 diabetic subjects
GFR was correlated to LBM percentage assessed by DEXA (R=0.32), BIA and mean of BIA and anthropometric assessment from Deurenberg's formula
In matched groups, predicted percentage of LBM values were overestimated in non-uremic subjects, and underestimated in non-uremic diabetic subjects. In uremic diabetic subjects, the error was intermediary.

Author Conclusion:

In diabetic subjects with chronic kidney disease, lean body mass should be measured, rather than predicted. A good evaluation is possible, even without DEXA.

Funding Source:

Other:

not reported

Reviewer Comments:

The authors claimed a good agreement between antropometry and BIA methods compared to DEXA in measuring lean body fat mass in patients with diabetes and CKD. However, Bland and Altman plot showed a great difference between the limits of agreement (approximately 6.0kg).
Most of the results were based on correlation coefficients, which compromised the clinical importance of the outcomes
Percentage of lean body mass (LBM) to DEXA measurements in 10 non-diabetic uremic, 10 non-uremic diabetic and 10 uremic diabetic subjects were compared in table 1, but there was no description on how these patients were selected. Small sample increases risk for type two error.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		No
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	No
	2.2.	Were criteria applied equally to all study groups?	???
	2.3.	Were health, demographics, and other characteristics of subjects described?	No
	2.4.	Were the subjects/patients a representative sample of the relevant population?	No
3.	Were study groups comparable?		???
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	No
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	???
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	???
4.	Was method of handling withdrawals described?		No
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	No
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	???
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	No
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		No
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	N/A
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	N/A
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	No
7.	Were outcomes clearly defined and the measurements valid and reliable?		???
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	???
	7.5.	Was the measurement of effect at an appropriate level of precision?	???
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	???
	7.7.	Were the measurements conducted consistently across groups?	???
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		No
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	No
	8.2.	Were correct statistical tests used and assumptions of test not violated?	No
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	No
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	N/A
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	No
9.	Are conclusions supported by results with biases and limitations taken into consideration?		No
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	No
10.	Is bias due to study's funding or sponsorship unlikely?		???
	10.1.	Were sources of funding and investigators' affiliations described?	No
	10.2.	Was the study free from apparent conflict of interest?	???