Pediatric Weight Management

PWM: Foods and Nutrients (2006)

Citation:

Johnson-Down L, O’Loughlin J, Koski KG, Gray-Donald K. High prevalence of obesity in low income and multiethnic schoolchildren: a diet and physical activity assessment. J Nutr 1997; 127: 2,310-2,315.

PubMed ID: 9405579
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  • To study the dietary intake and anthropometric indices of nine- to 12-year-old children from low-income, multiethnic neighborhoods in Montreal, Canada
  • To assess the prevalence of obesity and/or undernutrition
  • To explore issues of energy balance and describe the quality and quantity of dietary intake as related to indices of poverty, ethnicity and other family and personal characteristics.
Inclusion Criteria:

(In May/June 1993) Five students from each of the 130 classrooms (of fourth, fifth and sixth graders in the 24 participating schools) were randomly selected from the list of students who had agreed to participate in the study. Eligibility criteria included:

  • Nine to 12 years old
  • Complete diet anthropometric, physical activity data (N=498 of 650 randomly selected).
Exclusion Criteria:

Not specified

Description of Study Protocol:

This cross-sectional study was conducted as part of the evaluation of a school-based heart health promotion program for children. Each student was personally interviewed to obtain a 24-hour dietary recall. Questionnaires were completed to obtain other variables and anthropometric measures were taken following standardized forms.

Data Collection Summary:

Dependent

BMI (measure height and weight categorized according to age and gender-specific percentile of BMI using NHANES II standards, underweight ≤15th%, normal weight 15-85%, somewhat overweight 85th-90th%, moderately overweight 90-95th%, very overweight >95th%).

Independent

  • Dietary Intake (24-hour recall)
  • Underreporting of dietary intake (calculated ratio of reported energy intake to basal energy requirements in a resting and fasting state, a ratio of <1.8 was considered to indicate underreporting in children)
  • Quality of the diet (comparison with recommended levels)
  • Sociodemographic characteristics (questionnaire)
  • Income sufficiency (calculated)
  • Frequency of physical activity (seven-day recall, checklist).

Control Variables 

Multi-variate logistic regression model included:

  • Age
  • Sex
  • Number of children in household
  • Maternal education
  • Mothers' country of origin
  • Activity level.

Statistical Analysis 

ANOVA, pair-wise differences estimated using Scheffe procedure, logistic regression

Description of Actual Data Sample:

Original Sample 

Five students from 130 classrooms were randomly selected and 563 dietary interviews were conducted.

Withdrawals/Drop-Outs

  • One student did not complete interview 
  • 43 were ineligible because of age
  • 22 were missing anthropometric data.  

Final Sample 

498 school children from an ethnically diverse low income urban population with complete dietary, anthropometric and physical activity data.

Location

Inner-city neighborhood in Montreal, Canada

Race/Ethnicity

Ethnically diverse (mother's country of origin: 147 from Canada, 106 from Europe, 110 from Central/South America, 76 from Asia, 32 from other)

SES 

Low income (Approximately half below poverty line)

Age

Nine- to 12-years old

Summary of Results:

Prevalence of overweight

41.8% of boys and 36.8% of girls were above the 85th BMI percentile. Compared with the NHANES II reference population, there were 2.6 times more overweight children in our low income multi-ethnic sample than expected. Half of the overweight children were very heavy (>95th percentile).

Underreporting

The mean EI:BMRest in this study was 1.79±0.71, indicating no serious underreporting overall. There was no difference in EI:BMRest by age or gender. However, children in the highest BMI quartile showed evidence of significant underreporting; their mean value was 1.31±0.45. The pattern of decreasing EI:BMRest with increasing weight was evident in both boys and girls. Reported activity levels did not differ between weight groups, suggesting that the lower energy intake in overweight children was not attributable to lower activity levels.

Authors noted it was not appropriate to study the relationship of diet and BMI given the underreporting among the heavy children.

Obesity was not related to age, sex, number of children in the household, maternal education, mothers' country of origin, or activity level in multvariate analyses.

 

Author Conclusion:

Major nutritional risk factor found in this school-age population was obesity.

This underreporting among children as young as nine years may indicate that these children already perceive what are socially desirable responses to dietary interviews.

Such a systematic effects makes it difficult to evaluate whether diets are different between normal and overweight children. In addition, overweight children did not report doing less physical activity than normal weight children. Both conditions make it difficult to clearly identify diet or physical inactivity as the primary source of their energy imbalance.

Funding Source:
Government: Quebec Ministry of Health and Social Services, National Health Research and Development Program (Canada )
Not-for-profit
0
Foundation associated with industry:
Reviewer Comments:

Strengths

  • Assessed underreporting
  • Ethnically diverse sample
  • Measured height and weight.

Limitations

Unclear why 563 out of 650 randomly selected participants completed the dietary recall. Did the non-participants differ from participants?

Single dietary recall conducted on a weekday may not be representative of usual intake and could explain high proportion of underreporting.

Without measure of fat mass, difficult to assess whether higher BMI was due to excess fat or muscle. Authors report that in multivariate analyses, obesity was not related to any correlates traditionally associated with obesity but provide no explanation.

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? 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? ???
  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? ???
  2.2. Were criteria applied equally to all study groups? N/A
  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? ???
3. Were study groups comparable? N/A
  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? 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? ???
  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? ???
  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? Yes
  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? No
  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? ???
  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? ???
  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? 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? 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? 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