EAL

Pediatrics and Physical Activity

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate weight control behaviors, eating, and physical activity behaviors among obese, overweight, and nonoverweight female and male adolescents

Inclusion Criteria:

Not specified

Exclusion Criteria:

5% not included in analysis due to questionable BMI, missing height/weight data, incomplete surveys, or failure on series of internal consistency and reliability checks (usable data on 9,097)

Description of Study Protocol:

Recruitment

Drawn from statewide representative (geographically & SES) sample (n=9,943) using stratified random sampling design of public school students (n=61 schools) in Connecticut in 1995-96, The Voice of Connecticut Youth Survey (CYS). 83% enrolled students in sampled grades completed administered (in classroom) survey of 225 items (taken primarily from existing surveys).

Design

Students responded to questions about weight control behaviors, healthy eating behaviors, breakfast consumption, and vigorous physical activity.

Statistical Analysis

Logistic regression models to calculate odds ratios & 95% confidence intervals by weight status

Data Collection Summary:

(no blinding)

Independent variables

Weight control behaviors:
Dieting
Exercise
Vomiting
diet pills
laxatives
Healthful eating behaviors:
Lowfat milk, yogurt
Bread, rice, pasta, cereal, bagels
Fruits
Vegetables
Breakfast consumption
Vigorous physical activity

Dependent variables

BMI (self-report) classification: Underweight (< 15%; n=680), normal weight (15%-85%; n=6600), overweight (85%-95%, n=1215), obese (>95% BMI; n=602) using NHANES I cut-off points
Underweight significantly different from normal weight on number of analyses so dropped form further analysis so did not skew results; wanted focus specifically on overweight

Other variables

Sociodemographics
Gender
Grade level
Ethnicity
Family SES (parental education, employment)
Community SES

Control variables

Gender (separate models)
School (random effect)
Parent SES
Ethnicity
Grade

Description of Actual Data Sample:

N: 8,330 7^th, 9^th & 11^th grade public school students (4249 girls, 4081 boys)

Age

Ethnicity: 74% white, 9% black, 7% Hispanic, 10% other

Other demographics: 7% low, 42% low-mid, 30% high-mid, 21% high SES

Summary of Results:

Weight control behaviors

Prevalence of unhealthy weight control behaviors directly related to overweight status in both males and females

Eating

Breakfast eating – inversely related to overweight status in both males and females (p < .05 OB & OW vs. nonoverweight); Breakfast skipping remained significantly greater in OW & OB after controlling for confounders (Table IV list ORs for males & females by weight status). But skipping breakfast common among all youth (< 2/3 boys, <1/2 girls said usually ate BF on school day)
> 1 lowfat dairy yesterday inversely related to overweight status in females, but OR not significant after controlling for confounders
> 1 fruit yesterday – no relation
> 1 vegetable yesterday – no relation
> 1 grain yesterday inversely related to overweight status

Vigorous physical activity

> 3x/week Inversely related to overweight status in males and females

Author Conclusion:

Overweight adolescents use more unhealthy weight management strategies and are not engaging in healthier strategies, such as increased physical activity or healthier eating. These findings suggest the need to provide consistent messages about healthy weight loss methods to adolescents. Both overweight and nonoverweight male and female adolescents would benefit from messages about healthy lifestyle changes.

Funding Source:

Other:

no recorded funding

Reviewer Comments:

Strengths:

large sample size
statewide representative
diverse sample

Weaknesses:

self-report weight/height
control for variety of confounders, but did not control for physical activity or other diet measures in eating breakfast analysis
only 1 FFQ-type question used to assess intake of each food group

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?	Yes
	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?		No
	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?	No
	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?	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?	???