Energy Expenditure and Physical Activity

Citation:

Gibbons MR, Henry CJ, Ulijaszek SJ, Lightowler HJ. Intra-individual variation in RMR in older people. Br J Nutr. 2004;91(3):485-489.

 
Study Design:
Repeat measures
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  1. To aim of the present study was to determine the technical error of measurement (TEM) and intra-individual variation in RMR in older people.

Definitions

  • Steady state: Not defined
  • TEM: Technical error of measure.
Inclusion Criteria:
  1. Understand and give written consent
  2. Aged >60 years
  3. Non-smokers
  4. If female, post-menopausal.
Exclusion Criteria:

1.Refusal to consent

Description of Study Protocol:
  • Portable digital stadiometer and digital weighing scales. RMR measures were taken on two separate occasions (T1 and T2) within 1 month of the first measurement; A third measurement (T3) was made on 19 of 27 subjects and completed within 1 month of T2 measurement.

ANTHROPOMETRIC

  • Ht measured? Yes
  • Wt measured? Yes
  • Fat-free mass measured? No.

CLINICAL

  • Monitored heart rate? No
  • Body temperature? No
  • Medications administered? Some subjects took medications.

Resting energy expenditure

  • IC type: Delta trac with ventilated hood
  • Equipment of Calibration: Yes
  • Coefficient of variation using std gases: Yes 5% CO2 and 95% O2
  • Rest before measure (state length of time rested if available): “Rest in supine position”
  • Measurement length: 40 mins; eliminate first 30 mins
  • Steady state: First 10 mins as “settlin-in period
  • Fasting length: Y 12 hr
  • Exercise restrictions XX hr prior to test? Yes
  • Room temp: 22-24 C
  • No. of measures within the measurement period: 1
  • Were some measures eliminated? Yes the first 10 mins
  • Were a set of measurements averaged? 30 one-minute measures
  • Coefficient of variation in subjects measures? No
  • Training of measurer? Yes
  • Subject training of measuring process? Yes.
Data Collection Summary:

Outcome(s) and other measures

  1. Measured REE [(VO2, l/min), VCO2 (l/min; ml/kg/min), RQ, ventilation (l/min)].
  2. Independent variables of weight, height, age, and BMI.

Blinding used: No.

Description of Actual Data Sample:
  • N=27 older white, non-smoking and females were post-menopausal 7 M; 20 F
  • Mean age, y: 71.6±6.1 SD
  • Range, y: 61.8-82.8.

Statistical tests

  • All data normally distributed; Paired t-tests; Anthropometric compared with National Diet & Nutrition Survey using one-sample t-tests, p vales <0.05 were significant
  • Total error of measure and coefficient of reliability are reported.
Summary of Results:

ANTHROPOMETRIC

All Mean (±SD) Range

Wt, kg

71.6±6.1 61.8-82.8

Ht, m

1.67±0.08 1.49-1.81

BMI, kg/m2

26.2±4.2 18.8-34.4

Men

Wt, kg

75.1±7.0 66.5-82.8

Ht, m

1.75±0.04 1.70-1.77

BMI, kg/m2

25.5±4.2 21.9-34.4
Women

Wt, kg

70.3±5.3 61.8-83.8

Ht, m

1.65±0.07 1.49-1.77

BMI, kg/m2

26.5±4.2 18.8-34.3

RMR in MALES & FEMALES

  • Males have a higher absolute RMR than females (1411±152 vs 1277±122 kcal/d, respectively).

TEM

  • TEM for all 27 subjects was 282 kJ (or 67 kcals) (R=0.80).

COEFFICIENT OF VARIATION BY GENDER

  • The CV after T1 and T2 for male and female was 3.6% and 2.5%, respectively
  • The CV after all three measurements was comparable with measurements made for T1 and T2 for male and females, 4.0% and 3.0%, respectively.
  • The intra-individual coefficient variation in RMR range for 6 males subjects was 1.1 to 8.5% and for 20 females was 0.3 to 12.5%.

BODY WEIGHT VARIATION BY GENDER

  • There was a mean body weight decrease in males and females but the results were still similar to RMR values expressed as kJ/d (kcals/d).

3-WAY ANOVA OF RMR BETWEEN THREE MEASUREMENT OCCASIONS B/T FIRST AND FINAL 15 MIN OF MEASUREMENT

  • While there were no significant differences in RMR across measurement times, measurement error was a significant component of total variation as reflected in the low [Analyst note: Typo as discussion states error due to HIGH R value of R=0. 83].
  • Although on average RMR does not vary significantly across T1, T2, and T3, the significant interaction (of time of measurement times subjects) (P<0.001) reflects a high degree of within-subject variability, in that individuals’ RMR does not track across each period of measure.

FAO/WHO/UNU MEASUREMENT

  • Compared with measured RMR, the FAO/WHO/UNU overestimated RMR in 16 females and 6 men. In females, RMR was overestimated by 7%±5 (Range 2-20%) and in men by 10%±5 (Range 2-18%)
  • Both genders group mean weight fell within the overweight classification.

MEDICINE

  • There was no significant difference in the RMR of medicine users vs. non-medicine users. (P>0.05).
Author Conclusion:

As stated by the author in body of report:

  • The intra-individual variation in RMR seen in the elderly was low and similar to that seen in younger age groups; however the study also confirms that a high degree of within-subject variability.”
  • “Three subjects had a large CV of 9.9, 16.8, and 7.9% and these large variations could be due to the subjects being in an anxious state ... not fasted, or engaged in strenuous activity on the morning of one of the measures or onset of illness.”
  • “It is important to ensure that subjects adhere to the protocol to minimize intra-indiviudation variation in RMR.”
Funding Source:
Government: Fifth Framework (European Union)
Reviewer Comments:

Strengths 

  • Appropriate statistics
  • Explained sampling methods (clinics, groceries, libraries)
  • Identify grip strength to indicate “health” of elderly
  • Adequate discussion of calorimetry procedures, including calibration and use of statistics to compare if first 15 min measure is different than second 15 minute measure.

Generalizability/Weaknesses

  • “Generalizable to female older adults; unclear if generalizable to male older adults and very old due to limited sample sizes (i.e., 7 Males, and frequency of individuals >80 years not reported)."
  • More information on whether steady state was achieved during the entire measure or to identify the quantify the amount of rest before 1st measure is needed.
  • Did not specify which FAO/WHO/UNU equation was used (weight only vs. height, weight)?
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? N/A
  1.2. Was (were) 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 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? 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? 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? 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? No
  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 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? 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? Yes
  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