PWM: Eating Behaviors of Children (2006)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To clarify the impact of parental obesity and lifestyle factors on obesity in preschool children.
Inclusion Criteria:
not specified
Exclusion Criteria:
  • Those whose parental anthropometric data were not obtained (n=199),
  • those who did not answer one or more questions concerning PA, eating habits, and sleeping habits (n=534).
Description of Study Protocol:

Recruitment – Subjects were selected from the Toyama study of children (born in 1989) at health checkups routinely done on 3-year-old children by local governments in Japan.

Design – Questionnaire on lifestyle and environmental factors of children and past histories of parents was distributed to Toyama study participants beforehand and was collected at the checkup.  Data from initial survey (e.g., Takahashi, 1999) were reanalyzed using newly proposed cutoff points for childhood obesity, using original categories of lifestyle variables (instead of dichotomized ones – to get at dose-response), and adjusting for months after birth.

Statistical Analysis

  • Unpaired t-tests or Chi2  to test differences between included and excluded subjects
  • Logistic regression to do multivariate analysis (Hosmer-Lemeshow test to validate all models)
Data Collection Summary:

(no blinding)

Independent variables

  • Snacking irregularity (regular, almost regular, irregular)
  • Snacking frequency (1, 2, 3, >4 times/d)
  • Breakfast (daily, almost daily, rarely)
  • Wake up time (<6, 6-7, 6-8, >8 AM)
  • Bedtime (<9, 9-10, 10-11, >11 PM)
  • Amount of daily sleep – with or without naps (<9, 9-10, 10-11, >11 hours)
  • Amount of daily nap time (<1, 1-2, 2-3, >3 hours)
  • Physical activity relative to peers (<, =, >)
  • Outdoor play time (<30, 30-60, 60-120, >120 min)
  • Parental OB (based on self-report BMI >25)

Dependent variables

  • Obesity based on BMI (measured) >17.55-18.18 for males and 17.28-17.76 for females depending on age; values correspond to adult BMI of 25 (Cole et al. BMJ 2000;320:1240)

Control variables

  • Gender
  • Age
Description of Actual Data Sample:

Final sample – 8,941 (723 obese; 51% boys)

Original sample – 10,177 children in study population; 9,674 (95%) parents completed questionnaire

Age – 3.4 y (2.5-4.3 y)

Ethnicity – not specified

Other demographics – not specified

Location – Japan

Summary of Results:

Included vs. excluded subjects

  • No differences in age, child BMI, parental BMI, and lifestyle variables (data not shown)
  • Factors associated with obese in multivariate models adjusted for age and gender –
  • obese mother (OR=2.62, 95% CI 2.12-3.25)
  • obese father (OR=1.74, 95% CI 1.47-2.06)
  • Outdoor play time (see Table 1 for ORs; more obese with less time)
  • Wakeup time (see Table 1 for ORs; more obese with earlier time)
  • Sleeping hours including naps (see Table 1 for ORs; more obese with less time)
  • Snacking regularity, snacking frequency, breakfast skipping (as well as PA relative to peers, bedtime, sleeping hours excluding naps, and hours of naps) were NOT significantly associated with obesity

Factors associated with Obesity in multivariate models adjusted for age, gender, parental OB, outdoor play, and sleeping hours including naps entered simultaneously) –

  • obese mother (OR=2.56, 95% CI 2.07-3.17)
  • obese father (OR=1.70, 95% CI 1.43-2.02)
  • Sleeping hours including naps (see Table 2 for ORs)
Author Conclusion:

Eating and exercising habits were not significantly associated with obesity. These results indicate that parental obesity and short sleeping hours are possible risk factors for obesity in preschool children.

Funding Source:
Government: Ministry Health and Welfare (Japan)
Foundation associated with industry:
Reviewer Comments:

Strengths: Examines multiple potential related factors; large sample size.

Weaknesses: Definition of snacking not provided; not clear if snacking ‘irregularity’ refers to timing, consistency, amount, foods; no comparison of those included vs. excluded from study, demographics not provided and no testing of differences between cases and controls on demographic variables, limited discussion of study limitations.

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? No
  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? N/A
  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? ???
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? 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.) 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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? ???
  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? N/A
  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? 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? No
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