Worksheet: Haugen HA, Melanson EL et al, 2003 (1i, Diet Ind. Thermo)

Citation:
Haugen HA, Melanson EL, Tran ZV, Kearney JT, Hill JO. Variability of measured resting metabolic rate. Am J Clin Nutr. 2003;78(6):1141-5.

Study Design:
Repeat measures Crossover

Class:
C - Click here for explanation of classification scheme.

Quality Rating:
POSITIVE: See Quality Criteria Checklist below.

Research Purpose:

To assess the variability in repeated measurements of RMR within a single day and across days. Also, to evaluate the contribution of a midday meal on afternoon RMR. The following hypotheses were investigated

Repeated measurements of RMR on 2 d in either the morning or afternoon will be highly reliable and not significantly different.
RMR measured in the morning (after a 12-h fast and a 12-h abstention from caffeine, 12 h postexercise) and RMR measured in the afternoon ( after a 4-h fast and a 4-h abstention from caffeine, 12 h postexercise) will not be significantly different.
Different between morning and afternoon RMR measurements will be independent of the dietary characteristics of the midday meal (calories, carbohydrate, protein and fat).
The relation between RMR and fat-free mass (FFM) measured in the morning and afternoon will be comparable.

Definitions

Steady state: minimum of 15 min. of steady state, determined as a <10% fluctuation in oxygen consumption and <5% fluctuation in respiratory quotient.

Inclusion Criteria:
Understand and give informed consent Healthy adults.

Exclusion Criteria:
Refusal to consent Not meeting inclusion criteria Pregnant women.

Description of Study Protocol:

Two measurements were obtained in the morning between 0700-1000 under standard experimental condition (12 h fast, 12 h abstention from caffeine, 12 h postexercise)
Two measurements were obtained in the afternoon between noon and 1600 under less stringent condition (after a 4 h fast, 4 h abstention from caffeine, 12 h postexercise).
All measurements were obtained in a 2-wk period.

ANTHROPOMETRIC

Ht measured? Yes
Wt measured? Yes
Fat-free mass measured? Yes

CLINICAL

Monitored heart rate? Not stated
Body temperature? Not stated
Medications administered? None

Resting energy expenditure

IC type: Ventilated hood (Metabolic Cart)
Equipment of Calibration: Duplicate calibration were performed on the flow meter with the use of 3.0 L syringes and on the gas analyzers
Coefficient of variation using std gases: Yes
Rest before measure (state length of time rested if available): 30 min (morning) vs. 15 min (afternoon)
Measurement length: 15-20 min.
Steady state: Valid RMR was a minimum of 15 min of steady state
Fasting length: 12 hr vs. 4 hr
Exercise restrictions XX hr prior to test? 12 h
Room temp: 21-24 C
No. of measures within the measurement period: 2 repeated measurements in the morning and in the afternoon
Were some measures eliminated? Not stated
Were a set of measurements averaged? Yes and no, depends on statistic purpose
Coefficient of variation in subjects’ measures? Yes
Training of measurer? Not known
Subject training of measuring process? Not known

DIETARY

On the days that the afternoon measurements were obtained, subjects recorded their food intake (breakfast) before the 4 h fast. Energy and micronutrient contents were determined using FOOD INTAKE ANALYSIS SOFTWARE

Intervening factor

Controlled for:

Nicotine consumption (1hr refrain)
Exercise (12 postexercise).

Data Collection Summary:
Outcome(s) and other measures Measured RMR Independent variables of weight, height, age, BMI, and fat-free mass, fat mass. Blinding used: Not applicable; based on study design, yes

Description of Actual Data Sample:

Total N=34
(N=10 males; N=24 females)

Statistical tests

Pearson’s product-moment correlation coefficients were calculated to examine relations among the variables.
Paired t tests were used to test for differences between 2 means (e.g., mean RMR between visits 1 and visits 2)
Repeated-measures analysis of variances (visit by time) was used to evaluate the main (visit and time) and interaction effects)
Multiple regression analysis was used to determine potential predictors of differences between morning and afternoon RMR, especially to examine the relation between dietary intake and differences in RMR.

Summary of Results:

ANTHROPOMETRIC (Mean±SD)

	Women	Men
Age, y	36.9±11.7	40.0±10.9
Wt, kg	68.0±12.2	78.2±9.5
BMI	25±4.9	25.3±2.7
% body fat	32.2±10.6	20.7±10.3

Reproducibility of repeated measurements of RMR

Morning: The correlation coefficient for the morning measurements was r=0.86
Afternoon: Afternoon measurements were high correlated R=0.90

RMR rate: Morning vs. afternoon

The morning RMR was 1509.7±33.7 kcal/d (visit 1 and 2); and 1597.9±32.5 kcal /d (visit 1 and 2). The afternoon RMR was significantly higher than the morning RMR (P<0.001). The 2 measurements were highly correlated (r=0.90). The absolute mean difference between morning and afternoon measurements was 99 kcal/d, or an elevation of 6%.

Repeated-measurements analysis of variance

There was no significant visit effect (p=0.628),which indicated that the RMR was not significantly different when measured at the same time on different days.

The time effect was significant (p<0.0001), which indicated that the RMR was significantly higher when measured in the afternoon.

The day-by-time effect was not significant (p=0.807), which indicated that the RMR was not significantly different when measured on different days at the same time of day.

Multiple regression analyses and correlation coefficients

Multiple regression analyses showed that dietary characteristics were not significant predictor of the difference in RMR from morning to afternoon.

The difference in RMR between the morning and afternoon was poorly correlated with energy, grams of protein, fat, CHO, and % of CHO and fat.

RMR and FFM

FFM was highly correlated with RMR measured in the morning and in the afternoon.

MEASUREMENT PROCESS

Number of measurements: 2
Length of measurements: 15-20 min until steady state achieved.
Steady state: <10% fluctuation
RQ: <5% fluctuation

MEASUREMENT TIMING

Sleep or rest: Rest
Physical activity: 12 h postexercise
Food intake: 12 h vs. 4 hr fast
Various times in the day: am vs. pm

INDIVIDUAL CHARACTERISTICS

Healthy adults. 1 hr refrain from nicotine consumption

Author Conclusion:

“Measurements on the same day and across days were reliable, and differences among measurements were not clinically significant. On the basis of these findings, it would be acceptable to measure RMR under conditions that are less stringent than the current standard conditions.”

“On the basis of the results of the current study, we concluded that

RMR measured on 2 days under similar conditions will provide comparable results.
RMR measured in the afternoon will be significantly greater than RMR measured in the morning; the difference will be 5-6%
RMR can be measured in the afternoon with the expectation that the measurements will be ~ 100 kcal /d higher than morning measurement.

FFM is significantly correlated with RMR measured in both the morning and afternoon.”

Funding Source:

Industry:

Healthetech Inc.

Other:

Reviewer Comments:

Strengths

Great study design with appropriate and comprehensive statistics. Intervening variables (measurement process, exercise, nicotine) were controlled.
Relevant and valid study.

Generalizability/Weaknesses

Sample size is relatively small. Results only apply for healthy adults between age 25-60 Y.
The difference between morning and afternoon measurements can be results of 12h vs. 4h of fasting, or 15-min vs. 40-min rest before measurements, not the time of the measurements
Dietary intake was recorded for correlation analysis. However, the study design does not control for diet. The effect of dietary composition (ex, high protein vs., high CHO) on RMR can not be established.
Body composition were measured, but not taken into account in statistics.
Since FFM was highly correlated with RMR, study can be greatly improved if body composition (FFM) was controlled for data analysis.
Limitation of the study was not discussed. Although the conclusions were based on the statistical results, investigators failed to compare the effect of 12h- vs. 4 hr fasting on RMR measurements.

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 the specific intervention(s) or procedure (independent variable(s)) identified?	N/A
	1.2.	Was the outcome(s) (dependent variable(s)) clearly indicated?	N/A
	1.3.	Were the target population and setting specified?	N/A
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?	N/A
	2.2.	Were criteria applied equally to all study groups?	N/A
	2.3.	Were health, demographics, and other characteristics of subjects described?	N/A
	2.4.	Were the subjects/patients a representative sample of the relevant population?	N/A
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 used? (Concurrent preferred over historical controls.)	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 or cross-sectional 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. Criterion may not be applicable in some cross-sectional studies.)	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?		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?	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.)	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?	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?	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?	N/A
	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?	N/A
	7.5.	Was the measurement of effect at an appropriate level of precision?	N/A
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	N/A
	7.7.	Were the measurements conducted consistently across groups?	N/A
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?	N/A
	8.2.	Were correct statistical tests used and assumptions of test not violated?	N/A
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	N/A
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposedora 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?	N/A
	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?	N/A
	9.2.	Are biases and study limitations identified and discussed?	N/A
10.	Is bias due to study's funding or sponsorship unlikely?		No
	10.1.	Were sources of funding and investigators' affiliations described?	N/A
	10.2.	Was the study free from apparent conflict of interest?	N/A