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Healthy Non-Obese Ethnic Adults (2010-2012)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To measure total energy expenditure-derived energy requirements in a biracial population of older adults without limitations to daily life and to test these empirical measures against national and international recommendations.
Inclusion Criteria:
  • Subjects from Health ABC study cohort
  • Aged 70 - 79 years
  • Population was stratified for sex and race (51.5% women, 41.5% black)
  • Reported an ability to walk 0.4 km and climb 10 steps without rest
  • Free of selected physical limitations in activities of daily living
Exclusion Criteria:
  • Life-threatening cancers
  • Participation in any research study involving medications, modification of eating/exercise habits
  • Plans to move out of the area in next 3 years

Substudy exclusion criteria:

  • Recent blood transfusion or IV fluid administration
  • Use of supplemental oxygen or insulin
  • Overnight travel immediately before or during the energy expenditure measurement period
Description of Study Protocol:

Recruitment

Subjects from the Health, Aging and Body Composition Study, which was initiated in 1997.  The energy expenditure substudy was conducted between July 1998 and June 2000 and it included a race- and sex-stratified random selection of participants from the larger study.  The substudy was found to be representative of the overall Health ABC study cohort. 

Design:  Cohort Study 

Blinding used (if applicable):  not applicable

Intervention (if applicable):  not applicable 

Statistical Analysis

Normality of the data was ascertained through the Kolmogorov-Smirnov test.  Differences between groups were tested by factorial ANOVA with race, sex and site as main effects.  RMR analyzed by ANCOVA.  RMR values adjusted for FFM were calculated as different percentiles of the population FFM.  Predictive equations of RMR were derived by using multiple regression analysis.

Data Collection Summary:

Timing of Measurements

Testing protocols were completed in field centers during visits over a 2-week period.

Dependent Variables

  • Total energy expenditure measured by doubly labeled water method
  • Resting metabolic rate measured through indirect calorimetry and respiratory gas analysis  
  • Activity-related energy expenditure calculated as 0.92 X TEE - RMR, assuming 8% for diet induced thermogenesis
  • Body composition measured by DEXA
  • Body weight 

Independent Variables

  • Age
  • Race
  • Sex

Control Variables

  • Site
Description of Actual Data Sample:

Initial N: 3075 participants in cohort, 323 subjects were enrolled in the energy expenditure substudy

Attrition (final N):  288 persons, 35 excluded from statistical analysis.  9 did not complete protocol, 2 did not collect urine samples, 8 had inconsistencies in stable isotope data, 2 had highly variable RMR measurements, 14 did not undergo DXA measurements during study timeframe.

Age: see Results

Ethnicity: see Results

Other relevant demographics:

Anthropometrics

Location:  Pittsburgh, PA and Memphis, TN

 

Summary of Results:

 

 

Black Women (n=67)

White Women (n=77)

 Black Men (n=72) White Men (n=72) P value - Sex P value - Race

Age (years)

74.6 +/- 3.2

74.8 +/- 2.8

 74.8 +/- 2.9 75.1 +/- 3.2 0.56

0.52

BMI

28.6 +/- 5.9

26.2 +/- 5.3

 27.1 +/- 4.5 27.6 +/- 4.2 0.73

0.12

Weight (kg)

73.5 +/- 16.8

67.2 +/- 13.8

 81.6 +/- 14.6 83.5 +/- 12.5 <0.0001

0.26
FFM (kg) 43.8 +/- 6.6 40.1 +/- 5.6 59.2 +/- 8.1 58.0 +/- 6.1 <0.0001 0.004
Fat mass (kg) 29.5 +/- 11.1 26.7 +/- 8.9 22.0 +/- 7.9 25.0 +/- 7.6 <0.0001  0.85
Fat mass (%) 39.1 +/- 6.4 38.9 +/- 6.3 26.4 +/- 6.0 29.4 +/- 5.3 <0.0001 0.04 
TEE (kcal/day) 1904 +/- 369 1885 +/- 286 2324 +/- 436 2521 +/- 396 <0.0001 0.03
RMR (kcal/day) 1131 +/- 170 1150 +/- 170 1363 +/- 187 1454 +/- 191 <0.0001 0.007
RMR adjusted for FFM (kcal/day) 1234 +/- 110 1341 +/- 101 1216 +/- 136 1307 +/- 138 0.07 <0.0001
RMR adjusted for FFM and FM (kcal/day) 1224 +/- 109 1311 +/- 100 1227 +/- 136 1330 +/- 134 0.44 <0.0001
TEE - RMR (kcal/day) 774 +/- 297 735 +/- 216 962 +/- 345 1066 +/- 311 <0.0001 0.28
AEE (kcal/day) 620 +/- 272 584 +/- 197 775 +/- 313 865 +/- 284 <0.0001 0.32
AEE (kcal/d/kg) 8.7 +/- 3.5 9.0 +/- 3.5 9.7 +/- 4.2 10.4 +/- 3.4 0.007 0.21
PAL 1.69 +/- 0.24 1.65 +/- 0.21 1.71 +/- 0.24 1.74 +/- 0.22 0.07 0.97

Other Findings

Total energy expenditure was lower in women (~530 kcal/day, P < 0.0001) than in men because of women's lower RMR and AEE.

Fat-free mass explained the sex difference in RMR, but body weight failed to account for the women's lower AEE (~1 kcal/kg/day, P = 0.007).

Blacks had lower total energy expenditure than did whites (~100 kcal/day, P = 0.03) and that was explained by blacks' lower RMR.

Physical activity level (TEE/RMR) did not differ significantly between sexes and races (1.70 +/- 0.23).

The World Health Organization recommendations overestimated TEE by 10 +/- 15% (P < 0.0001) in women but not in men, and the dietary reference intakes (DRIs) were accurate to 0 +/- 14% (P = 0.1).

Both WHO and DRI recommendations are based on an underestimated physical activity level, and WHO recommendations are based on overestimated RMR. 

Author Conclusion:
This study of well-functioning older adults confirms the racial difference in energy metabolism and supports the use of the 2002 DRIs.  Because the DRIs and WHO recommendations underestimated PAL, new predictive equations of energy requirements are proposed.
Funding Source:
Government: NIH
Reviewer Comments:
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) N/A
  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) N/A
 
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? 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? 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? Yes
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? 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? 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? N/A
  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? 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? No
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