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PWM: Foods and Nutrients (2006)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To compare lean children at high and low risk of obesity and already obese children to assess their energy and macronutrient intake in relation to their obesity risk status and current adiposity.

Inclusion Criteria:

Children age six to eight years living with biological parents.

 

Exclusion Criteria:

No subject who agreed to take part was excluded.

Description of Study Protocol:
  • Children recruited through schools in the Coleraine area in Northern Ireland
  • Parents of children were contacted by letter and interviewed, if expressed interest after receiving letter
  • All measurements took place during the school term and were conducted over a three-year period.
Data Collection Summary:

Dependent Variables 

  • Obese children (N=14) defined as BMI greater than 95th percentile according to British growth standards
  • High-risk children (N=50) had at least one biological parent with a BMI greater than 29.5kg per m2
  • Low-risk children (N=50) had two lean biological parents (BMI less than 25kg per m2)
  • Body weight and height: Measured following standardize protocol
  • Body fatness: Difference between body weight and lean mass; isotope dilution during the measurement of energy expenditure.

 

Independent Variables

  • Total energy expenditure (TEE): Doubly labeled water
  • Dietary Intake: Total energy and macronutrient composition - fat, carbohydrate and protein (seven-day weighed dietary record)
  • Parent’s adiposity: Measured height and weight.

Control Variables 

  • SES: Father’s occupation
  • Gender.

Statistical Analysis

  • One-way ANOVA
  • Regression analysis.
Description of Actual Data Sample:
  • Original sample: Not specified; Based on calculations with response rate, original sample equaled 184 children
  • Withdrawals/Drop-outs: The response rate of those contacted and eligible to participate was 62%
  • Final sample: 114 healthy children (66 boys, 48 girls) divided into three groups based on their risk for obesity or their own obesity status
  • Location: Northern Ireland, UK
  • Race/Ethnicity: Predominantly White European population
  • SES: Mixed socio-economic background
  • Age: Six to eight years old.
Summary of Results:
  • The BMI of HR and OB parents did not differ significantly from each other
  • The accuracy of EI reporting was assessed by comparison with TEE. Reported EI fell short of measured TEE in all groups by two, five and 14% in the LR, HR and OB groups, respectively. There was some evidence of under-reporting in the OB group.

Total Energy

There was no significant difference in total energy intake between groups.

Macronutrients

  • In absolute terms, the OB group consumed more fat (+12g per day) than the LR group (P<0.05), but no significant differences were observed between any of the groups in protein or carbohydrate intakes
  • When expressed in relative terms (% energy intake), carbohydrate and fat intakes in the OB subjects were approximately 4% lower (P<0.05) and 3% higher respectively than the LR group (P<0.05). No other significant differences were observed between groups in the proportion of energy from the macronutrients.

Linear Regression Results

  • Body fatness as the dependent variable and protein, carbohydrate, total sugar and fat intake (% total kcal) as separate independent variables
  • Percent energy from fat was the only significant predictor of body fatness in stepwise regression (r2 =0.05, P<0.05)
  • When boys and girls were assessed separately, there was a significant relationship for boys, but not for girls.
Author Conclusion:
  • The data were analyzed in three ways to examine the relationship between energy and fat intake and body fatness. In every case the data indicated that adiposity is positively associated with dietary fat intake.
  • Children in the obese group consumed significantly more fat than their lean counterparts, those in the highest quarter of fat intake were significant fatter than those in the lowest quarter and dietary fat intake was a significant predictor of body fatness.
Funding Source:
Industry:
Kellogg's, Coca Cola, Mars (all UK), Sugar Bureau
Food Company:
Commodity Group:
Reviewer Comments:

Strengths

High quality of dietary, adiposity and energy expenditure assessment tools.

 Limitations

  • Cross-sectional study design
  • Method of study selection may have introduced bias since approximately 40% of eligible children who were invited to participate in the study declined
  • Small number of subjects in OB group relative to the size of the LR and HR group – could have limited power to detect differences between groups.

 

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) Yes
  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) 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.) Yes
  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.) Yes
  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? 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? 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? 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? 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? 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)? Yes
  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? 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