Pediatric Weight Management

Pediatrics and Physical Activity

Citation:

Horn OK, Paradis G, Potvin L, Macaulay AC, Desrosiers S.  Correlates and predictors of adiposity among Mohawk children.  Preventive Medicine 2001; 33: 274-281.

PubMed ID: 11570831
 
Study Design:
Longitudinal/cross-sectional
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

The objective of this study is to examine the correlates and predictors of adiposity, including several physical activity indicators, among a cohort of Mohawk elementary school children participating in a community based diabetes prevention project.

Inclusion Criteria:
Not Specified
Exclusion Criteria:
Not Specified
Description of Study Protocol:

Measure were taken over 3 weeks at the schools. Body composition was taken by a trained nurse. Measures of height, weight, subscapular and triceps skinfolds as well as hip and waist circumferences were measured. In class children in grades 4-6 completed a questionnaire while children in grades 1-3 completed them at home with their parents. Additionally a one mile (4-6) or half mile (1-3) walk/run was completed.

Data Collection Summary:

Dependent Variable

  • Body fatness – subscapular skin fold thickness

Independent Variable

  • Physical activity – categorized (everyday, 4-6, 1-3, no days)
  • Physical inactivity – 6+ programs/day = excessive, those who watched less were moderate)

Confounders:

  • Ethnicity (Mohawk)
  • Gender

Statistical Analyses: Separate analyses were carried out for each gender.

Cross-sectional analyses:

  • Zero-order correlation coefficients were computes and variables significant at a P .10 were retained for multivariate analyses.
  • The significance of each independent variable was tested suing stepwise regression while control first for other variables of the same category followed by demographics.

Longitudinal analyses: Same format as cross-sectional.  Predictors for the skinfold measures at follow-up were derived while controlling for the baseline skinfold assessment.

Description of Actual Data Sample:

Initial N: 198 Mohawk Students (95 boys, 103 girls)

Age: average age 7.5 (±1.3)at baseline

Summary of Results:

Girls

  • For girls, not playing outside during the past week, watching excessive television, and being involved in community and summer sports were associated (p<.10) with higher skinfold thickness at both evaluation rounds.
  • Among girls, being less physically active (R² = .04), watching excessive TV (R² = .14) and summer sports (R² = .03) were associated with increased subscapular skinfold thickness at baseline.
  • The mean subscapular skinfold thickness among girls who watched excessive TV was 30% higher than among those who watched less TV.
  • Independent predictors for skinfold thickness CHANGE in girls were baseline skinfold thickness (R² = .67), younger age (R² = .01), watching TV (R² = .01 and higher relative PA (R² = .01).

Boys

  • Among boys, being involved in summer sports (R² = .09) and not playing outside (R² = .05) were independent correlates of the log of the subscapular skinfold thickness at baseline. The only independent predictor of skinfold thickness change in boys was baseline skinfold thickness (R² = .72).
Author Conclusion:
  • For cross-sectional analyses, the strongest predictor of skinfold thickness, in girls, was excessive television watching.
  • Longitudinal analyses showed the strongest predictor of skinfold change was the baseline subscapular skinfold thickness. TV viewing was a weak independent predictor of adiposity change in girls in longitudinal analyses but not for boys.

Overall conclusion:

Baseline skinfold thicknesses predicted follow-up skinfolds. For girls, TV viewing appears to be associated with adiposity.

Funding Source:
Government: National Health Research & Development Program, Health Canada, Kahnawake Education, Mohawk Council of Kahnawake
Reviewer Comments:

For boys, it appears that physical activity may be have a bigger impact whereas for girls physical inactivity may have a greater impact.

Limitations:

TV viewing – anything less than 6 programs was seen as moderate, they did not include a “low” group. In addition, no validiation was done for the TV viewing measure.

Strength: 

both cross-sectional and longitudinal analyses were done.

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? N/A
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? N/A
  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? 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? 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? 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? 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? 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 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