EAL

CKD: Energy Requirements (2001)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The purpose of this study was to measure energy expenditure and substrate oxidation rates of major fuels in patients with renal failure by indirect calorimetry.

Inclusion Criteria:

1. Acute renal failure with septicemia using the following criteria:

a. fever >38.5° C

b. leukcocystosis: >15 g/L with predominance of granulocytes

c. 2 + blood cultures or >1 + blood culture + isolation of the same organism from the focus of infection

2. Acute renal failure without septicemia.

3. CRF for 1 yr without dialysis

4. Untreated azotemia (BUN >36 mmol/L) before initiation of hemodialysis

5. CRF undergoing maintenance hemodialysis

Exclusion Criteria:

1. Local infections without bacteremia

2. Diabetes mellitus

3. Thyroid dysfunction

4. Neoplasm

5. Other chronic disease

6. Unstable disease as determined by medical history, physical exam, or laboratory data.

Description of Study Protocol:

Recruitment

Methods not specified.

Design: Cross-Sectional Study

a. Single measurement of indirect calorimetry

b. Anthropometric measurements: Biochemical data: BUN, Hb

c. Dietary intake data: Kcal, protein by 4 wk food records for CRF without dialysis and CRF on dialysis and control subjects

d. Nutrition support: ARF: 35 kcal/kg and 1 g amino acid/kg/day; CRF without dialysis: 0.6 g protein/kg

e. Metabolic studies conducted after 10-12-hr fast for resting energy expenditure, immediately after dialysis for those with CRF on dialysis, ARF after the diagnosis of septicemia, azotemia immediately after admission to the hospital

f. resting energy expenditure measured by indirect calorimetry by measuring oxygen consumption and carbon dioxide production at 1 minute intervals and the mean of 30 minutes was calculated.

g. urea nitrogen appearance rate was calculated from 24-hr urea nitrogen excretion

Blinding Used (if applicable):

Not applicable.

Intervention (if applicable):

RMR measured by indirect calorimetry

Statistical analysis

Univariate analysis of variance. Differences between groups tested using Tukey's test.

Data Collection Summary:

Timing of Measurements

RMR measured by indirect calorimetry.

Dependent Variables

RMR measured by indirect calorimetry

Independent Variables

10 - 12 hour fast

Control Variables

Description of Actual Data Sample:

Initial N = 110 patients, 44 women, 66 men. 86 patients with various forms of renal failure and 24 age-matched healthy controls

Attrition (Final N): No attrition since one measurement only

Age - see table below

Ethnicity - not given

Other relevant demographics and anthropometrics: controls were age-matched. BUN and Hb for all groups were significantly different than controls (P<0.05) and wt was significantly lower than controls for all groups except ARF with septicemia (P<0.05).

Group	N	age	BUN	Hb	Wt
			Mmol/L	g/L	kg
ARF with septicemia	18	47.3+3.9	33.1	10.2	69.5
ARF no septicemia	11	50.7+6.1	28.9	9.5	65.0
Pre-ESRD	17	57.5+3.7	18.9	11.1	64.3
Untreated azotemia	15	56.7+4.9	49.6	8.8	56.7
CRF on dialysis	25	52.0+2.6	25.1	7.1	52.0
Control subjects	24	44.3+1.5	5.8	14.4	78.3

Location - University of Vienna, Austria

Summary of Results:

Metabolic Studies:
Group	REE	UNA
	Kcal/min/1.73 2	mg/min/1.73 2
ARF septicemia	1.28	8.72
ARF no septicemia	1.05	7.88
Pre-ESRD	0.91	5.00
Azotemia	1.01	4.06
CRF:dialysis	1.03	5.05
Control subjects	0.96	7.25

There were no differences in REE except for ARF with septicemia, which was higher than controls (P<0.05). Urinary nitrogen appearance rate was significantly lower than controls for Pre-ESRD, Azotemia and CRF with dialysis (P<0.05).

Author Conclusion:

Renal failure has little if any influence on energy expenditure as long as no severe infection is present. In particular, no hypometabolic state was seen in patients with untreated uremia. The main cause of malnutrition and wasting in patients with CRF undergoing conservative treatment or regular hemodialysis is a reduced energy intake and not an increased energy expenditure.

Funding Source:

Reviewer Comments:

Although this was a cross-sectional study that cannot show a causal relationship, resting energy expenditures were nearly identical for all groups except for the group with septicemia that was significantly higher. Energy intakes were less than recommended for those with CRF with and without dialysis.

Because of the small numbers of subjects in some groups, lack of statistically significant differences may be a type II 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?		Yes
	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?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	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")?	N/A
4.	Was method of handling withdrawals described?		N/A
	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?	N/A
5.	Was blinding used to prevent introduction of bias?		N/A
	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.)	N/A
	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?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	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?	Yes
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	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?	Yes
	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?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	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?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	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?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes