Pediatric Weight Management

PWM: Foods and Nutrients (2006)

Citation:

Muecke L, Simons-Morton B, Wei Huang I, Parcel G. Is childhood obesity associated with high-fat foods and low physical activity? J Sch Health 1992; 19-23.

 
Study Design:
Combined Cross-sectional & Case-control study design
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To ascertain the association between exposure to high-fat foods & low levels of exercise & obesity.

Inclusion Criteria:

Third grade children in attendance at 4 Texas schools. Obesity classification according to percentile based on NHANES II, 1976-1980.

Exclusion Criteria:

Children who were absent or excused from fitness evaluation for medical reasons.

Description of Study Protocol:

Risk associated with exposure to high-fat foods, low physical activity, & both combined was evaluated. For each individual risk factor, all participants were assigned into tertiles defined as High, Medium & Low. Odds ratios were calculated for each of the two risk factors using the tertile suspected of posing the least risk as the referent group. To evaluate possible synergy between the two exposures, an odds ratio also was calculated for children classified according to presence & absence of both risk factors.

Data Collection Summary:

Dependent:  Obesity: BMI > 85th% (ht & wt measured following standardized protocols)

Independent: 

  • Total number of high-fat foods over 3-day period, these scores were rank-ordered & roughly broken into tertiles (High-fat food was defined as any food with > 50% calories from fat)
  • Self-reported consumption of high-fat foods (3, 24-hr food recall checklist);
  • Self-reported level of physical activity (Daily Physical Activity Self-Report Record (DPAR)).

Control Variables:  Analyses were stratified by Hispanic surname.

Statistical Analysis:  Logistic regression & Pearson correlation analysis.

Description of Actual Data Sample:

Original Sample:  240 children (121 boys, 119 girls)

Withdrawals/Drop-Outs:  3 children with missing data.

Final Sample:  237 third grade, preadolescent students.

Location:  four Texas City, Texas schools

Race/Ethnicity:  represent a range of ethnic heritage.

SES:  middle-SES neighborhoods

Age:  8-10 y

Summary of Results:

Neither high-fat food intake nor reported level of physical activity were independent risk factors for this condition (obesity).

High-fat food consumers:

The group classified as “high” based on self-reported consumption of high-fat foods did not show a sig. increased risk of obesity (OR = 1.08, 0.54-2.2) & no evidence of a dose-response relationship was present.

Combined risk factors:

When individuals with both exposures were compared to individuals with neither exposure, an approximately 38% (OR=1.38) higher risk of obesity was noted; this association was NOT significant.

Pearson correlations between BMI & high-fat food intake were not significant.

Author Conclusion:
These results did not show an increased risk associated with either intake of high-fat foods or low levels of physical activity when experienced alone, but did indicate a possible synergistic effect between the two exposures when both were present in the same child.
Funding Source:
Other: no funding reported
Reviewer Comments:

Limitations:

Classification of children according to both variables resulted in small cell sizes, thus decreasing the power of the analysis.
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? No
  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? No
  2.3. Were health, demographics, and other characteristics of subjects described? No
  2.4. Were the subjects/patients a representative sample of the relevant population? No
3. Were study groups comparable? No
  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? No
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  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? No
  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.) No
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? No
  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? Yes
  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? No
  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? No
  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? No
  8.1. Were statistical analyses adequately described and the results reported appropriately? No
  8.2. Were correct statistical tests used and assumptions of test not violated? No
  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)? No
  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? No
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? No
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? No