Pediatric Weight Management

Pediatrics and Physical Activity

Citation:

Maffeis C, Talamini G, Tato L. Influence of diet, physical activity and parents’ obesity on children’s adiposity: a four-year longitudinal study. International Journal of Obesity and Related Metabolic Disorders 1998;22: 758-764.

PubMed ID: 9725635
 
Study Design:
Longitudinal/CS
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To assess the relationships between diet, physical activity level, parents’ obesity at baseline and subsequent fat gains in a group of pre-pubertal Italian children over a four year period.
Inclusion Criteria:

Not specified

Exclusion Criteria:

Not specified

Description of Study Protocol:
  • After an initial briefing, the child and her/his parents had a diet history interview with a dietician who also filled out a socio-economic status questionnaire of the family and the physical activity level of the child. Parents then recorded their height and weight.
  • A pediatrician took height, weight and skin fold thicknesses of the children along with completing a physical exam to exclude any other health problems other than obesity.
  • Four years later each family was invited back to get height and weight measurements for the child. 

 

Data Collection Summary:

Independent Variables:

  • Diet
  • Body composition
  • Physical activity (questionnaire filled out by the parents)
  • Parent’s obesity (BMI based on self-report height and weight)
  • Television viewing (questionnaire filled out by the parents)

Dependent Variables:

  • Obesity – relative BMI >120%
  • Adiposity at baseline (relative BMI = (BMI/BMI @ 50th percentile for age and gender) x 100))
  •  Adiposity at follow-up (relative BMI)

Confounders: 

  • Age
  • Gender
  • Parents BMI

Statistical Analyses:

  • A paired T-test, or when appropriate the non parametric Wilcoxon test was used to compare anthropometric data and dietary variables of the children at baseline and 4 years later and between the obese and non-obese children.  Bonferonni correction was used to adjust for multiple analyses.
  • Multiple regression was used to examine the degree of association between variables at both baseline and follow-up.  It was run both with and without adjustment for variables that might potentially affect relative BMI (age, gender, energy intake, percent of energy intake as fat, percent of energy intake as protein, percent of energy as carbohydrates, parents’ BMI, TV viewing and time spent on vigorous activity).
  • An autoregressive unbalanced repeated measures model was run to take relative BMI at the age of 8 and relative BMI at the age of 12 simultaneously into account in the analysis as DV’s.  All other variables were regarded as covariates (age gender, parents’ BMI, energy and nutrient intake, TV viewing time and time spent in vigorous activities.)
  • A multivariate logistic regression analysis with backward stepping of variables was used to assess the prediction level of the variables measured at baseline on the variation of relative BMI at follow-up as well as Odds Ratios. 
  • Finally, a multiple regression analysis using the changes in relative BMI expressed as departures from the average change over 4 years as the DV.  The same covariates were used.
Description of Actual Data Sample:

 

Initial N: 298 (148 male, 150 female)

Age: pre-pubertal children, age 8.7 + 1.1.

 

Ethnicity: Caucasian

Anthropometrics: 112 children completed the follow up and therefore have complete data. Equal proportions came from public and private schools.

Summary of Results:
  • Obese children spent more time watching TV than non obese children (P<.05) and less time performing vigorous play and physical exercise (P<.05)
  • Relative BMI was correlated to TV viewing time (r = .27, P<.001) and inversely correlated to time spent on vigorous activity (r = -.19, p < .05).
  • The final regression equation revealed that the mothers BMI and TV viewing (independent variables accounted for 17% of the children’s relative BMI variance at the age or 8 (R = .42, P < .001)
  • Multiple regression analysis recognized the mother’s and father’s BMI as the only independent variables that accounted for 13.5% of the children’s rel BMI variance at the age of 12 (R = .37, P < .001).
  • Autoregressive unbalanced measures recognized the mother’s (Coefficient = 2.53, .26) and father’s BMI (Coefficient = 2.07, .23) as the only independent predictors.
  • Logistic regression performed on change in relative BMI found significant associations were only for relative BMI at baseline.
  • Multiple regression on change in relative BMI found that TV and time spent in vigorous PA were not significant predictors of change in relative BMI
Author Conclusion:
  • Parent’s obesity was the most powerful predictor of child obesity at 8 as well as 12 years of age for both males and females.
  • TV viewing and physical activity were not retained as significant predictors after parents obesity was entered in the models.
  • Rel BMI at 8 is correlated to rel BMI at follow-up. Therefore the role of childhood obesity as a predictor of obesity later in life is supported. 

Overall conclusion:

Parent obesity is the most important risk factor for obesity in children.

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

Limitations:

  • Relative BMI is not as commonly used as BMI and therefore it is more difficult to compare these results to the results of other studies.
  • Because the cut points depend on the mean of the group the results may be confounded
  • Longitudinal analyses relied on self report values form age 8 rather than values taken.
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? N/A
  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? 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? 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? Yes
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? 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? 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.) 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? 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? No
  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? No
  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? 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? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  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? N/A
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  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)? N/A
  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? N/A
  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? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A