EAL

PWM: Physical Activity and Inactivity of Youth (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate relationships between children’s body mass index (BMI) and parent reports of children’s television and video game/computer habits, controlling for other potential risk factors for paediatric obesity.

Inclusion Criteria:

None specified

Exclusion Criteria:

None specified

Description of Study Protocol:

As part of a larger epidemiological study these Australian schools were selected and stratified by sector (government, Catholic, and independent), 24 total schools. One class at each year, level (preparatory to 6^th grade) was then randomly selected at each school.

Statistical Analyses:

Independent t-tests were used to compare mean hours of television and video game/computer use by sex. Relationships between child BMI z-scores and single independent variables were investigated using one way ANOVA.
Multivariate ANOVA was used to investigate relationships between child BMI z-score and variables that were significantly related in the one way ANOVA.
Logistical regression was used to calculate the odds of being overweight or obese as a function of television viewing and video game/ computer use with and without adjusting for family and sociodemographic variables.

Data Collection Summary:

Dependent Variables

BMI (wt/ht²) – measured

Independent Variables

Children’s television viewing (parental report/# of hours)
Children’s video game habits (parental report/# of hours)
Children’s computer habits (parental report/ # of hours)

Confounders

Parental BMI (reported height and weight)
Parental education (reported)
Number of siblings
Food intake (reported)
Organized exercise (reported)
General activity level (reported)
Age (5-6, 7-8, 9-10, 11-12)

Description of Actual Data Sample:

2862 children age 5 to 13 from Australia primary schools.

Summary of Results:

The mean BMI z-scores were .60 (SD 1.07) for boys and .42 (SD 1.06) for girls and increased in a stepwise fashion with increasing hours of television viewing (p = .001) and video game/ computer use (p = .09).

One way ANOVA confirmed significant relationships between mean BMI z-scores and the four television viewing categories for the whole sample (F = 10.2; P<.001) and for boys and girls separately (F, 4.6, P<.01, and F = 5.0, P<.01).

Higher mean BMI scores were associated with less organized exercise (F = 11.3, P < .001) and being less active (F = 7.0, P<.001) than other children the same age.

In multivariate analyses, TV and video games were not significantly associated with obesity.

Parental BMI and food intake were significant predictors and organized exercise was still significant but only accounted for .6% of variance in BMI.

Television viewing was associated with child BMI (F = 4.5, P<.01) but only explained a small amount of variance.

Author Conclusion:

Television viewing but not video game/computer use was associated with modestly increased odds of overweight and obesity, after adjusting for maternal BMI and family variables.

Having overweight or obese parents far outweighs TV viewing as a risk for obesity.

Overall conclusion:

Television viewing was modestly positively associated with child’s BMI.

Funding Source:

Government:	Victorian Department of Human Services Division of Public Health
University/Hospital:	University of Melbourne, Royal Children's Hospital (Australia)

Reviewer Comments:

Limitations:

Cross sectional data
Reported height and weight for parent’s BMI
The use of the same 2 scales for boys and girls may have limited results as boys had higher BMI than girls.
The logistic analyses also didn’t’ report separate results for boys and girls.

Strengths:

Large sample
Randomly selected population sample

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?	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%.)	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?		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?	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?	No
	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?		Yes
	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?	Yes
9.	Are conclusions supported by results with biases and limitations taken into consideration?		N/A
	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