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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 assess the relationship between nutrient intake, partitioning of food intake, parents’ overweight and adiposity in a group of children.
Inclusion Criteria:
not specified
Exclusion Criteria:

Serious chronic diseases excluded from recruitment; among those recruited 52 excluded due to missing data, 153 excluded due to under/over-estimation of energy intake (based on EI/BMR [formulas based on weight, height, age, sex] cutoffs of 1.4 & 2.8 [decided arbitrarily using published references]

Note: no statistical differences in age, % fat mass, gender, weight predicted for height, parents’ BMI between those included and excluded from analysis]

Description of Study Protocol:

Recruitment

735 children (living in 6 areas in north-east Italy from a number of school districts within each area to obtain a representative sample of children of different SES and environmental backgrounds) were recruited for survey (details described elsewhere)

Design

students completed questionnaire & had anthropometric measurements taken at school

Statistical Analysis

  • Relationships between %FM & %energy intake at different meals, parent’s BMI, diet composition, and energy intake/BMR ratio assessed by Pearson product moment linear correlation in total sample in 2 sexes separately.
  • Multiple regression analysis with a stepwise procedure using relative adiposity as the dependent variable and parents’ BMI, fat intake (% energy intake) dinner intake (% energy intake), energy intake/BMR ratio (a gross index of validity of self-reported energy intake), and sex (dummy variable) as independent variables. 
  • Kruskal-Wallis test used to compare %FM, skinfold thickness & RBW% among 6 groups of children selected on bases of parents’ body size (OB, OW, normal)
Data Collection Summary:

(no blinding)

Independent variables

  • Energy intake (EI)
  • Nutrient intake
  • % distribution of intake of energy among meals
  • (diet history with mother & child by dietitian)

Dependent variables

  • % body fat (FM%; Lohman’s formulae based on triceps & subscapular skinfold thicknesses)
  • BMI (measured wt/ht)
  • Fat free mass (FFM; weight – fat mass)
  • Fat mass (FM/ % body fat x weight)
  • Relative body wt (RBW%; wt predicted for ht based on Tanner’s growth tables)
  • Status – obese (RBW% >120%), overweight (RBW% 110-120%)

Other variables

  • Parents’ BMI (self-report weight/height):  obese >30, overweight =25-30, normal wt <25

Control variables

  • gender (separate analyses); parents’ BMI; dinner intake; EI/BMR ratio in final multivariate model.
Description of Actual Data Sample:

N – 530 (278 males, 252 females)

Age – 7-11 y

Ethnicity – 72% white (63% northern European), 21% Asian, 7% other

Other demographics – not specified, but weight, BMI or SBW grouping not associated with educational level of parents

Summary of Results:

Meals

  • No difference in % energy intake by sex (but males had greater absolute energy intake than females)
  • Significant simple correlations (bivariate; no control) in total sample (males & females) with %FM: 
    • [-] CHO (%EI; p<.01)
    • [+] Fat (%EI; p<.01)
    • [-] Breakfast (%EI; p<.05)
    • [+] Dinner (%EI; p<.05)
    • [-] Energy intake/BMR (p<.01)
    • [+] Mother’s BMI (p<.01)
    • [+] Father’s BMI (p<.01)

Snacks 

  • No difference except slightly lower %EI in males than in females
  • Significant simple correlations (no control) in total sample (males & females) with %FM: 
  • [-] Night snack (%EI; p<.001)
  • NS with morning & afternoon snack
  • No snack variables ended up in final model
  • All the independent variables [listed under stats], except percentage of fat intake, were included in the final model.  The equation was able to explain approx 19% (R=0.44, p<.001) of inter-individual fat mass percentage variability (%EI at dinner explained 2% of this variability)
Author Conclusion:

Diet composition did not contribute to explain the children’s adiposity when the parents’ overweight (BMI) was taken into account. However, the percentage distribution of the intake of energy among the different meals, particularly at dinner, contributed to explain inter-individual variance of fatness in children of both sexes.  This relationship needs to be confirmed through longitudinal studies designed to explore eating patterns in pre-obese children.

Funding Source:
University/Hospital: University of Verona (Italy)
Reviewer Comments:

Strengths:

  •  Large sample size, control for several confounders,
  • comparison of subjects included and excluded from analysis,
  • excluded likely dietary under- & over-reporters,
  • representative sample of north-east Italy

Weaknesses:

  • Demographics not described (measured?),
  •  how meals & snacks defined not provided (subject self-defined?)
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? 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? No
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
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? 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? 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.) 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? 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? 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? 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)? Yes
  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? Yes
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? ???