Pediatric Weight Management

Pediatrics and Physical Activity

Citation:

Delany, J.P., Bray, G.A., Harsha, D.W., & Volaufova, J. Energy expenditure in African American and white boys and girls in 2-y follow-up of the Baton Rouge Children’s Study.  Am J Clin Nutr 2004;79:268-273.

PubMed ID: 14749233
 
Study Design:
Cross-Sectional Study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

The purpose of this study was to determine the relations between race, sex, Tanner stages, and EE.

Inclusion Criteria:

All children were initially at Tanner stages 1 or 2 when first enrolled in the study.

Exclusion Criteria:

None stated

Description of Study Protocol:

Children were contacted to repeat measures of EE and body composition made 2 years earlier. Body composition (assessed by using the 4-compartment model which included bone mineral content measured by DEXA – density measured by underwater weighing – and total body water measured by isotope dilution), Tanner stage, and RMR were assessed during the information session.  Thermic effect of food (TEF) and TDTotal daily EE were measured at the school in a mobile laboratory.  A second 30 minute RMR was taken a few days after determination of body composition.  On another day, the children were dosed with doubly labeled water.

Statistical Analysis

The components of EE were compared by using the general linear model analysis of variance.  Various indexes were used in the ANOVA models as covariates to adjust for differences in body composition.  Tukey’s multiple comparison adjustment was used for post hoc tests.  Simple regression analysis was conducted on initial and follow-up EEs.

Data Collection Summary:

Timing of Measurements

Children were contacted to repeat measures of EE and body composition made 2 years earlier.

A second 30 minute RMR was taken a few days after determination of body composition.  On another day, the children were dosed with doubly labeled water.

Dependent Variables

  • initial EE components
  • follow-up EE components

Independent Variables

  • Obese vs Lean

Control Variables

  • Tanner stage
Description of Actual Data Sample:

Initial N:

The sample consisted of 114 African American and white girls and boys  

Attrition (final N):

Age: aged 12.7±0.1y

Ethnicity: African American, white

Other relevant demographics: stratified as obese or lean from the Baton Rouge Children’s Study. 

Anthropometrics (e.g., were groups same or different on important measures)

Location: Baton Rouge, LA

Summary of Results:

White children had significantly higher Total daily EE and RMR (P<0.03) than did AA children when fat free mass was considered. Boys had significantly higher TDEE and RMR than did girls, even after adjustment for difference in size. 

Total daily EE (P<0.01) and activity-related energy expenditure (P<0.066) were lower in the obese children after adjustment for body weight. 

Activity-related EE did not differ significantly between obese and lean children. 

There was a strong relationship between initial and 2-year Total daily EE (r2=0.56, P<0.0001) and RMR (r2=0.36, P<0.0001).  There was a significant decrease in activity-related EE in both racial groups.  African American children had significantly more lean limb mass than did white children.

Author Conclusion:

Average Total daily EE did not change over 2 y, but RMR increased significantly, and activity-related EE decreased significantly. Differences in trunk and limb lean mass of white and AA children may explain some of the ethnic differences in EE.  The decrease in physical activity over 2 y may contribute to the risk of obesity.

Funding Source:
Government: NICHD
University/Hospital: Pennington Biomedical Research Center
Reviewer Comments:

The obese children expended no more energy in physical activity and tended to have an even lower Activity-related EE than did the lean children after adjustment for the 18 kg of additional body weight observed in the obese children.

Therefore, a lower Activity-related EE may be a risk for weight gain or maintenance of increased body weight in these obese children.  Finally, during the important transition through adolescence, physical activity levels decreased in all of the subgroups, which indicates a potential risk of the development of obesity during this growth spurt.

Limitations:

Strengths:

Longitudinal, large sample size, consistency of the decline in physical activity with the use of 3 methods

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) 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? 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.) 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? 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? ???
  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? N/A
  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? 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? 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? No
  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? N/A
  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