EAL

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

Citation:

Lazzer S, Agosti F, Silvestri P, Derumeaux-Burel H, Sartorio A. Prediction of resting energy expenditure in severely obese Italian women. J Endocrinol Invest. 2007; 30 (1): 20-27.

PubMed ID: 17318018

Study Design:

Cross-Sectional Study

Class:

D - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

The aims of this study were to develop and cross-validate new equations for predicting resting energy expenditure (PREE) in severely-obese Italian women and to compare their accuracy with previously-published equations.

Inclusion Criteria:

Females 18 years to 60 years of age with a BMI of at least 40kg/m², who gave written informed consent.

Exclusion Criteria:

Subjects with overt metabolic or endocrine disease (such as diabetes, hypothyroidism, hypertension, etc.) and those who were taking regular medications known to influence metabolism were excluded.

Description of Study Protocol:

Recruitment: Subjects were recruited from the Division of Metabolic Diseases, Italian Institute for Auxology
Design: Cross-sectional study
Blinding used (if applicable): Implied with measurements.

Statistical Analysis

Bland Altman analysis was used to test for bias (mean difference) and limits of agreement between measured REE (MREE) and predicted REE (PREE). For the development and cross-validation of new equations, the data set of 182 MREE values was randomly split into two groups: A calibration group (cohort 1) for development of predictive equations and a cross-validation group (cohort 2) for the validation of the predictive equations.
In cohort 1, simple linear regression was completed on variables related to MREE and a new equation was obtained by stepwise selection
Bland Altman was used to cross-validate in cohort 2
Predictive equations were also validated against the data from an independent group of obese women, composed of 50 women aged 20 to 73 years, recruited by the Human Nutrition Research Centre of Clermont-Ferrand, France
Accuracy was defined as the percentage of subjects whose REE was predicted to within 5% of measured REE.

Data Collection Summary:

Timing of Measurements

Measurements were taken in the morning on fasting subjects.

Dependent Variables

REE was measured after an overnight fast by indirect calorimetry, using a SensorMedics Vmax 29, for 30 minutes (the first five to 10 minutes of adjustment were excluded from analysis)
REE was estimated using the following equations: Harris-Benedict, Bernstein, WHO/FAO/UNU, Owen, Mifflin, Nelson, Siervo, Huang and Livingston.

Independent Variables

BMI
Waist and hip circumference
Fat-free mass (FFM) and fat mass (FM), measured by bioelectrical analysis.

Control Variables

Sex
Age.

Description of Actual Data Sample:

Initial N: 182 obese women
Attrition (final N): 182 women
Age: 19 years to 60 years
Ethnicity: Italian
Other relevant demographics: Not reported
Anthropometrics: Mean BMI, 45.6kg/m²
Location: Italy.

Summary of Results:

Key Findings

Two new specific equations based on anthropometric REE = Weight x 0.042 + Height x 3.619 - 2.678 (R²=-0.66; SE=0.56MJ) or body composition parameters REE = FFM x 0.067 + FM x 0.046 + 1.568 (R²=0.63; SE=0.58MJ) were generated
Mean PREE was no different from the mean measured resting energy expenditure (MREE) (less than 1%; P>0.800) and REE was predicted accurately (95% to 105% of MREE) in 60% of subjects
The WHO/FAO/UNU, Harris Benedict and Siervo equations showed mean differences less than 2% and PREE was accurate in less than 44% of subjects
The Huang, Mifflin and Livingston equations showed a mean PREE under-estimation over 5.0% (P<0.001) and PREE was accurate in under 38% of subjects
The Owen, Bernstein and Nelson equations showed a greater PREE underestimation (more than 14%; P<0.001) in more than 90% of subjects
REE increased significantly (+13.5%; P<0.001) when BMI increased from 42.4kg/m² to 54.2kg/m². After adjusting for FFM, it was still 10.2% higher (P<0.001).

Author Conclusion:

These new prediction equations allow an accurate estimation of REE in groups of severely-obese women and result in lower mean differences and lower limits of agreement between PREE and MREE than previous commonly-used equations.

Funding Source:

Government:	Progetti di Ricerca Corrente, Italian Institute for Auxology, Milan, Italy
University/Hospital:	University of Auvergne Research Centre; University of Udine.

Reviewer Comments:

Large sample size of obese females, but age ranged from 19 years to 60 years and recruitment methods were not described.

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?		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?	Yes
	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.)	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?		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?	Yes
	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?	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?	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?	N/A
	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)?	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