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Healthy Non-Obese Adults (2010-2012)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  • Determine the reliability of REE measurements at different times of the day and at different intervals after the last meal
  • Compare predicted BEE and measured REE to measured BEE in healthy controls and hospitalized patients with liver cirrhosis.

 

Inclusion Criteria:

Controls

  • Hospital and university staff and students
  • Healthy.

Patients

  • Biopsy-proven liver cirrhosis
  • Afebrile
  • Stable clinical condition.

 

 

Exclusion Criteria:

None specified.

Description of Study Protocol:

Recruitment

Procedures not specified; convenience sample of patients.

Design

  • For purpose #1: Trend study
  • For purpose #2: Cross-sectional study.

Statistical Analysis

  • Analysis of variance used to compare five-minute interval readings for 30 minutes for
  • Mean energy expenditure (EE)
  • Respiratory quotient (RQ) 
  • REE1 (one to two hours after breakfast)
  • REE2 (before lunch)
  • REE3 (before dinner)
  • Calculated Harris-Benedict energy expenditure (HBEE)
  • Basal energy expenditure (BEE)
  • Significance: P≤0.05.


 

Data Collection Summary:

Timing of measurements

Two consecutive measurement days: 

  • One day measured under basal conditions
  • One day measured under resting conditions: Subjects with an odd trial number were studied under basal conditions on the first day and resting conditions on the second day; subjects with an even number were studied in reverse order
  • Resting day: Three measurements
    • 08:30 to 10:00 (one to two hours after breakfast)
    • 11:30 to 13:00 (before lunch)
    • 16:30 to 18:00 ( before dinner).

Dependent variables

  • Measured energy expenditure (Weir equation) (basal and resting) and respiratory quotient (RQ):
    • IC type: Metabolic monitor measuring inspiratory oxygen concentration and the difference between inspiratory, and between inspiratory and expiratory oxygen concentration with a paramagnetic differential oxygen; expired CO2 level is measured continuously with infrared sensor, inspiratory CO2 level of room air is measured every two minutes per sensor
    • Rest before measure:
      • Basal energy expenditure: 30 minutes rest in supine position
      • REE day: Rest time not indicated; control subjects allowed to perform usual work between resting measurements; patients allowed to walk but spent most of day seated
    • Diet: Recorded amount, composition and time of food intake prior to the measurement
    • Measurement length: 30 minutes with 20 minutes used to address steady state
    • Fasting length: Fasting eight hours prior to measurement on basal day
    • Exercise conditioning 24 hours prior to test? Performed work duties
    • Room temperature: Not mentioned
    • Number of measures were they repeated? REE day: Three consecutive measures
    • Coefficient of variation? In controls was 5±3%
    • Equipment of Calibration: Yes prior to measurements the sensors are calibrated with a gas mixture of known composition
    • Training of measurer? None reported
    • Subject training of measuring process? None reported
  • Predicted energy expenditure: Harris-Benedict equation.

 Independent Variables

  • Time of day
  • Basal vs. resting energy expenditure
  • Healthy controls vs. liver cirrhosis.

Control variables

  • Sex
  • Weight
  • Height
  • Age
  • BMI: Recorded on first day of testing.


 

Description of Actual Data Sample:
  • Attrition (final N):
    • Patient Sample:
      • N=10 with biopsy-proven liver cirrhosis; patients afebrile and in stable condition
      • Mean 48±14, range=22 to 69 (N=5 males; N=5 females)
    • Controls:
      • N=50 controls; gender not specified
      • Assigned into age categories of 10 to 19, 20 to 29, 30 to 39, 40 to 49, 50 to 59 years and each category containing five subjects
      • Mean age: 35±13 years
  • Anthropometrics:
    • Healthy sample: 
      • Weight: 72±14kg
      • Height: 177±9cm
    • Control sample:
      • Weight: 63±21kg
      • Height: 167±9cm
  • Location: The Netherlands.
Summary of Results:

Controls

  • BEE:
    • During the first five minutes
    • RQ was slightly lower than in the remaining period (0.81±0.09 vs. 0.840.07), P<0.001)
    • BEE was 12+9% higher than the remaining 25 minutes of recording (P<0.001)
  • REE:
    • RQ during the first resting measurement (RQ1) decreased from 0.91±0.12 in the first five minute period to 0.87±0.08 in the final period (P<0.001)
    • RQ2 decreased from 0.88+0.12 to 0.84+0.08
    • RQ3 from 0.90±0.11 to 0.82±0.07 (P<0.001). After the third five minutes recording the RQ difference between five-minute periods was no longer statistically significant in controls.
  • REE1: 
    • First five minutes of recording: 27+14% higher than last 25 minutes (significant, but P-value not given)
    • Second five minutes: 5.1+5.3% higher than remaining 20 minutes (P<0.05)
  • REE2:
    • First five minutes of recording: 28+13% higher than remaining 25 minutes of recording (significant, but P-value not given)
    • Second five minutes of recording: 5.2+5.1% higher than remaining 20 minutes (P<0.005)
  • REE3:
    • First five minutes of recording: 31+14% higher than remaining 25 minutes (significant, but P-value not given)
    • Second five minutes of recording: 6.0+3.8% higher than remaining 20 minutes (P<0.005).

Cirrhotic Patients

  • BEE:
    • RQ did not change during first five minutes and averaged 0.80±0.07 in the total 30-minute recording
    • During the first five minutes of recording, BEE was 5.4±2.9% (P<0.05) higher than in the remaining 25 minutes
  • REE:
    • RQ increased during the resting measurements only in REE2 (0.84±0.10 to 0.88±0.09) and REE3 (0.86±0.10 to 0.90±0.11); the increase was significant (P<0.05) from the first to the final five-minute period
  • Only in the first five-minute recording was REE higher than in the rest of the recording:
    • REE1: 8.1±7.2% (P<0.05)
    • REE2: 9.2±5.4% (P<0.001)
    • REE3: 9.3±4.3% (P<0.05). 

Energy Expenditure (kcal per day) of Healthy Controls Calculated by Harris-Benedict (HBEE), and Measured under Basal (BEE), Resting Conditions in the Morning (REE1), at Noon (REE2), and in the Afternoon (REE3) mREE and Calculated Estimates

 

  Controls   Cirrhotics  
  EE kcal per 24 Hours Percent BEE EE Percent BEE

BEE

 1,645±315  (100)  1,530±235  (100)

HBEE

 1,635±270  (100±8)  1,419±303  (93±10)

REE1

 1,808±365  (110±8)*  1,714±267  (112±6)*

REE2

 1,782±384  (108±8)*  1,715±238  (112±6)*

REE3

 1,775±316  (108±6)*  1,779±275  (116±7)*

*Statistical difference between HBEE and BEE and between REE and BEE; * P<0.05

  • The group mean of HBEE correctly predicted the group mean BEE. The difference between HBEE and BEE was large than 10% of the BEE in 11 of 50 controls (22%)
  • Resting measurements were 110+8% (REE1), 108+8% (REE2) and 108+6% (REE3) of the BEE (all P<0.05)
  • There was no statistically significant difference between the results of the three resting measurements; the mean coefficient of variation for resting measurements in the controls was 5±3%, range=0.8% to 10%
  • Resting energy expenditure was higher than basal energy expenditure measured at the same time of day, by 10±8% in controls and by 12±6% in cirrhotics.


 

Author Conclusion:

As stated by the author in body of report:

  • In our study, the initial five- to 10-minute values of energy expenditure were higher than in the remainder of the recording period. In controls, this may have been between hyperventilation as indicated by a higher RQ. However, the higher EE values at the onset of recordings were not due to a lower proportion of expired gas in the gas mixture entering the metabolic monitor, because this would result in underestimation of actual CO2 output and oxygen uptake.   
  • Resting energy expenditure can be reliably measured by indirect calorimetry with a ventilated hood system if the initial 10-minute values are deleted. After the first 10 minutes of each 30-minute recording period, the variation coefficient between three successive resting measurements was 5% in controls and cirrhotics.
  • The Harris-Benedict equation accurately predicts the mean basal energy expenditure in healthy controls, but individual predictions may be erroneous in both controls and patients with liver cirrhosis. In individual subjects, predicted EE was up to 21% lower than measured EE.
  • Basal and resting energy expenditure differ considerably in controls as well as in cirrhotic patients, so conditions under which measurements are performed should be standardized.
  • The magnitude of the BEE-REE difference in this study is equal to the 10%, reported by Elwyn et al, 1981.
Funding Source:
University/Hospital: University Hospital Dijkzigt
Reviewer Comments:

Strengths

  • Addressed steady state issues
  • Attempted to stratify by age.

Generalizability/Weaknesses

  • The defined basal measurements in controls were after they had driven to their worksite and so question achievement of true basal conditions
  • The elevated values in first five to 10 minutes of the resting measurements may reflect that there was not a resting period
  • Limited generalization to overall population as characteristics to participate was a health care worker in facility and contained self-selection bias
  • Small sample sizes (N=5) within each age range of control population; no gender or ethnic group identified
  • It does not appear that any HB factors were used when comparing BEE and HBEE
  • Measured weight but did not address in analyses.
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? ???
  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? ???
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.) 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? Yes
  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.) Yes
  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? 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%.) No
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? ???
  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? 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.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? No
  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? Yes
  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? N/A
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? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  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? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? No
  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)? No
  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? N/A
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