Adult Weight Management

AWM: Estimating Resting Metabolic Rate (RMR) (2014)

Citation:

Horie LM, Gonzalez MC, Torrinhas RS, Cecconello I, Waitzberg DL. New specific equation to estimate resting energy expenditure in severely obese patients. Obesity (Silver Spring). 2011; 19(5): 1,090-1,094.

PubMed ID: 21233808
 
Study Design:
Diagnostic, Validity or Reliability Study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To confirm the effectiveness of available predictive equations for REE in severely obese patients and develop a new predictive equation specifically for these subjects.
Inclusion Criteria:
  • Severely obese candidate for gastric bypass surgery
  • Considered sedentary
  • Provided written informed consent.
Exclusion Criteria:
  • Younger than 18 years of age
  • Had cancer, coronary heart disease, hepatic or pulmonary failure, chronic kidney disease, impaired thyroid function, pregnancy or were taking any medication that influences energy expenditure such as corticosteroids.
Description of Study Protocol:

Recruitment

Subjects were candidates for gastric bypass surgery.

Design

Diagnostic, validity or reliability study.

Blinding Used

Implied with measurements.

Statistical Analysis
  • The statistical analyses were performed using STATA version 9.2
  • The results are expressed in mean and SD
  • The paired T-test was used to compare the differences in REE estimated by predictive equations and IC
  • A comparison of REE between genders was assessed by Students unpaired T-test or Mann-Whitney U test as appropriate
  • In order to build a new equation, the sample was randomly separated by the statistical program into model building (50%) and validation (50%) sub-samples
  • A backward multi-variable linear regression was used to develop a specific predictive equation for REE in the model building sub-sample
  • All possible predictor variables were included (gender, age, weight, height, BMI, phase angle 50kHz resistance and reactance and 5kHZ, 50kHZ, 100kHZ and 200kHZ impedance, fat-free mass (FFM) and FM from BIA
  • The significant and stronger predictor variables were used to develop the predictive equation and the R2 measurements.
Data Collection Summary:

Timing of Measurements

All measurements made on the same day for each individual.

Dependent Variables

  • Body composition assessment was performed on each patient by bioelectrical impedance (BIA)
  • Four-frequency BIAs were measured on the model Bodystat, QuadScan 4000, Isle of Man, British Isles, operating at 5Khz, 50Khz, 100Khz and 200Khz
  • The test was performed according to the National Institutes of Health (NIH)
  • REE was measured using a ventilated-hood, open circuit indirect calorimeter under a canopy (Deltatrac Monitor II MBM-200, Datex-Engstrom Division; Instruments, Helsinki, Finland):
    • All subjects were admitted to the hospital at 7:00 a.m. after a 12-hour overnight fast and had been instructed to avoid any intense physical activity during the 24-hour period before REE measurement
    • After 30 minutes of resting in a recumbent position, oxygen consumption (VO2), and carbon dioxide production (VCO2) were measured continually for 35 minutes. The first five minutes of the measurement were discarded to ensure adequate acclimation.
    • Patients were instructed to avoid hyperventilation, fidgeting or falling asleep during the test.
  • Predictive equations for resting energy expenditure (REE):
    • Harris-Benedict
    • Mifflin-St. Jeor
    • Ireton-Jones
    • Owen.
  • A new equation was developed based on fat-free mass (FFM).
Independent Variables

Severely obese patients.
Description of Actual Data Sample:
  • Initial N: 120 subjects
  • Attrition (final N): 120 subjects (37 male, 83 female)
  • Age: Mean age of all patients 41.6±11.6 years
  • Other relevant demographics: Mean body weight 126.5kg±26.7kg
  • Anthropometrics: Mean BMI of all patients 46.88kg/m2±6.22kg/m2
  • Location: Brazil.

 

Summary of Results:

Key Findings

  • All predictive equations studied failed to estimate REE in severe obesity (low concordance correlation coefficient (CCC) and limits of agreement of nearly 50% of the sample ±10% of MREE)
  • The HB equation using actual BW exhibited good results for all samples when compared to IC (2,117kcal±518kcal per day by HB vs. 2,139±423kcal per day by MREE, P>0.01)
  • These results were blunted when patients were separated by gender (2,771kcal vs. 2,586kcal per day, P<0.001 in males and 1,825kcal vs. 1,939kcal per day, P<0.001 in females)
  • A new resting energy expenditure equation was developed as 560.43 + (5.39 x BW) + (14.14 x FFM). The new resting energy expenditure equation prediction, which uses FFM and BW, demonstrates higher accuracy, precision, CCC and limits of agreement than the standard PE in patients when compared to MREE (2,129kcal±45kcal per day vs. 2,139kcal±423kcal per day, respectively, P=0.1).
Author Conclusion:
The results of this study indicate that none of the available equations in the literature demonstrated good accuracy and correlation, when compared with MREE, for severe obese patients (BMI more than 35kg/m2). Additional validation work may be needed to confirm its usefulness in clinical settings. The new equation developed to estimate REE, which takes into account both FFM and BW, provides better results than currently available equations.
Funding Source:
University/Hospital: University of Sao Paulo Brazil
Reviewer Comments:
Limitations of the present study include the relatively small sample size and the disproportion of gender in the REE equations which could influence the value of adjusted R2.
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? 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? No
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  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.) 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")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? Yes
5. Was blinding used to prevent introduction of bias? Yes
  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.) Yes
  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? Yes
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? Yes
  6.6. Were extra or unplanned treatments described? Yes
  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? Yes
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? Yes
  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)? Yes
  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