Pediatric Weight Management

Pediatrics and Physical Activity

Citation:

Muller, MJ, Grund, A, Krause, H, Siewers, M, Bosy-Westphal, A, & Rieckert, H. Determinants of fat mass in prepubertal children.  Br J Nutr 2002;88:545-554.

PubMed ID: 12425735
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

The aim of the present study was to compare variables of metabolism, physical activity and fitness to body composition in normal and overweight children.

Inclusion Criteria:

None Stated.

Exclusion Criteria:

None Stated.

Description of Study Protocol:

Parents gave information about physical activity of their children as well as SES through a standardized questionnaire. Body composition was measured by anthropometric methods (height, weight, suprailiac and subscapular skinfolds) and bioelectrical impedance.  Resting EE and RER were assessed with indirect calorimetry.  Resting and 24h heart rate (HR) were measured with a heart rate monitor.  Activity related EE and physical activity level (PAL) were calculated.  Time spent with min by min HR>  Individual regression lines for HR vs VO2 on a bicycle ergometer were established.

Statistical Analysis

The significance of the biological data was tested by a factorial design using a two-way ANOVA considering the factors gender and weight status (overweight v. normal weight).  The significance of the questionnaire data was tested by X2 test.  Differences in resting EE, total EE, and activity-related EE observed between boys and girls matched for FFM were tested by the unpaired samples t test.  Multiple linear regression analysis was performed.

Data Collection Summary:

Dependent Variables

  • sum of skinfolds
  •  fat mass

Independent Variables

  • resting EE,
  • EE,
  • HR > FLEX HR

Control Variables

  • age
Description of Actual Data Sample:

Initial N: The sample included 48 prepubertal children (35 overweight, 13 normal)

Attrition (final N):

Age: between 5 and 11 years old

Ethnicity:

Other relevant demographics: All children were classified as Tanner staging <2. Overweight was defined as BMI>90th percentile.

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

Location:

Summary of Results:

Resting EE, resting EE adjusted (r 0.29, P<0.05), resting EE and HR>FLEX HR correlated with %FM and the sum of skinfolds at four sites.

When compared with normal weight children, watching television greater than 1 hour/day was more frequently observed in overweight children.

Author Conclusion:

When compared with normal children, overweight children had a lower measured v. estimated resting EE (resting EE) and spent more time watching television. In a stepwise multivariate regression analysis resting EE adjusted for FFM and resting EE were significant determinants of % fat mass and explained 29.7% of its variance.

Funding Source:
Reviewer Comments:

In the present cross sectional study, resting EE was the most important determinant of fat mass. These cross sectional results do not suggest that: 1) overweight children are relatively less active and also have less muscle strength than normal weight children; 2) a low physical activity and also a low muscular skeletal function contributes to overweight.

Limitations:

Inaccuracies associated with the measurement techniques.  Small sample size.

Strengths:

Multiple measures of activity.
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? No
  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) N/A
  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? 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? 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.) No
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? No
  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? Yes
  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? 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? 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? 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? 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? 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