EAL

PWM: Foods and Nutrients (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate the association between the obesity status of parents and dietary fat intake in their offspring
To determine the relation between dietary fat intake & body fat in children, taking into account the potential independent effects of physical-activity energy expenditure.

Inclusion Criteria:

Children recruited by word of mouth and newspaper advertisements.

Children resided in Burlington, VT or Akwesasne, NY

No other specific inclusion criteria given.

Exclusion Criteria:

not specified

Description of Study Protocol:

Families were recruited by newspaper advertisement & word of mouth. Children were recruited and divided into four groups based on their parents’ obesity status 1) nonobese mother & father (n=22); 2) obese mother, nonobese father (n=13), 3) nonobese mother, obese father (n=20), 4) obese mother & father (n=16).

Parents were instructed on how to complete the food frequency questionnaire & informed that intake was to represent the child’s eating habits over a 1-yr period.

Body composition was measured using bioelectrical resistance and skinfold-thickeness measurements. Weight and height were measured using standardized procedures. Body fat was estimated from subscapular and triceps skinfold thicknesses, weight, height²/resistance and sex by using an equation developed for children and using dual-energy X-ray absorptometry (DXA) as a criterion method (R² = 0.91).

Activity energy expenditure (AEE) was measured by total energy expenditure over 14 d -- post-prandial resting energy expenditure. (14 day total energy expenditure was measured by using the doubly labeled water method. Post-prandial resting energy expenditure was measured rather than 12-hour postabsorptive energy expenditure)

Data Collection Summary:

Dependent: (Bioelectrical resistance & Subscapular & tricep skinfold thickness & Height & Weight) – Fat mass (adjusted for fat-free mass)

Independent: Fat intake was adjusted for nonfat intake (FFQ); Fat-free mass & AEE.

Control Variables: Gender, Ethnicity, Physical activity energy expenditure (difference between total energy expenditure – measured over 14 d by the doubly labeled water method & postprandial resting energy expenditure – measured by indirect calorimetry)

Statistical Analysis:

Differences in subject characteristicsbetween sexes determined using unpaired t-tests.
Two way analysis of covariance (ANCOVA) model used to assess effect of sex and ethnicity on fat intake and fatmass in children.
First objective: Type III errors examined in a two-way ANCOVA model to examine influence of parental obesity on fat intake in children. (Dependent variable = fat intake, grouping variables were maternal (yes, no), paternal (yes, no) obesity; covariate was non-fat intake)
Second objective: multi-linear regression model used to examine the relation between fat mass and fat intake in children. (Dependent variable fat mass; independent variables were fat-free mass, fat intake, nonfat intake, and AEE.

Statistical Analysis System (SAS) for Windows; Quattro Pro for Windows and Statplan III were the programs used for statistical analyses.

Description of Actual Data Sample:

Original Sample: 80 children

Withdrawals/Drop-Outs: Data from 9 subjects were considered outliners.

Final Sample: 71 white & Mohawk children (36 boys, 35 girls).

Location: Burlington, VT & Akwesasne, NY

Race/Ethnicity: white & Mohawk

SES: not specified

Age: 4-7 y.

Summary of Results:

Dietary Fat:

A main effect for maternal obesity on children's fat intake was nearly significant (P=0.052)

A sig. correlation between fat mass & fat intake was noted in boys (r=0.48, P< 0.01) but not in girls after adjustment for physical-activity energy expenditure.

Author Conclusion:

The absence of a relation between fat mass and dietary fat intake in girls in this study was most likely complicated by the presence of maternal bias when mothers report their daughter’s intake.

The authors further speculate that mothers with obese daughters may be underreporting their daughter’s fat consumption because weight appears to be a greater concern for women than for men.

In conclusion:

Dietary fat is only one contributor to the development of obesity, and
Methodologic limitations of dietary intake measurement techniques may explain the consistent, but weak, effect of dietary fat intake on the variability in fat mass.

Funding Source:

Government:

USDA, NICHD, General Clinical Research Center NIH

University/Hospital:

University of Alabama at Birmingham, University of Vermont, Sims Obesity Nutrition Research Center

Not-for-profit

Foundation associated with industry:

Reviewer Comments:

Strengths:

Examined reported fat intake relative to reported nonfat intake.

Body composition measurements were well described and very thorough.

Concerns for this study:

Subject group not well defined; no inclusion/exclusion criteria given other than that they were children, 4 to 7 years old from the cities in which the study was done. It is impossible to know if subjects were truly representative of population.

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?	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?	Yes
	1.3.	Were the target population and setting specified?	Yes
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?	No
	2.2.	Were criteria applied equally to all study groups?	Yes
	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?	???
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)	Yes
	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?	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?	Yes
	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?	Yes
	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?	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?	N/A
	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?	Yes
	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?	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)?	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