EAL

Child Nutrition and Environment

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate the association between physical and social neighborhood environment and fifth-grade students' physical activity and obesity through multiple measures of neighborhood physical characteristics and social processes
To determine if, after controlling for children's sociodemographic characteristics, the physical environment would be negatively associated and the social environment would be positively associated with children's physical activity levels and if these levels correlated with childhood obesity.

Inclusion Criteria:

Participants in Healthy Passages, a multi-site, community-based, cross-sectional study of children's health
Student in grade five.

Exclusion Criteria:

None listed.

Description of Study Protocol:

Recruitment

Phase 1 of Healthy Passages study
The sample frame included all fifth-grade students enrolled in public schools with fifth-grade class enrollments of at least 25 students in three cities (Birmingham, AL; Los Angeles, CA; Houston, TX) and their metropolitan areas
Schools were selected by a two-stage probability sampling procedure. Schools were first selected randomly, with a school's probability of selection proportional to a weighted measure of its size.
All fifth-grade students in regular classrooms in the sampled schools were then invited to participate.

Design

Cross-sectional study.

Statistical Analysis

A logistic regression predicting the absence of BMI from the sociodemographic factors, site, and neighborhood social and physical environments found no evidence of selection (P>0.05 overall). Models with imputed income were also estimated and gave similar results.
Multi-variate models of categorical obesity outcomes and BMI with the physical and social neighborhood environments modeled as two latent variables were estimated. Latent variables are hypothesized unobservable constructs (such as a uni-dimensional true physical environment as it pertains to obesity) that can only be measured indirectly through a series of measures observed with error. The observed scales of more traffic, more physical disorder, low residential density and primarily residential neighborhood were used as indicators of the latent variable physical environment.
Collective efficacy, collective socialization of children, neighborhood exchange, social ties and perceived safety scales were used as indicators of the social environment
MPLUS software was used to estimate structural equation models with latent variables
All analyses accounted for the complex survey design appropriately adjusting standard errors for the effects of weights and the clustering of students within schools
In the first step of the multi-variate analyses, the measurements of models for each latent variable and its indicators were tested. Once confirmed, the corresponding structural models were estimated as shown in figure one of the article.
First , the structural models for the various measures of physical activity according to the form of the dependent variable were estimated
Next, a composite score was created for physical activity by summing standardized Z-scores of all physical activity variables; this composite was used in the structural models for child BMI (continuous) and two categorical measures of obesity status [binary (underweight or normal weight vs. overweight or obese) and ordinal (underweight or normal weight, overweight and obese)]
The following measures of fit were reported:
- Comparative fit index
- Root mean square error of approximation
- Standardized root mean square residual
The results are reported as standardized regression coefficients, which represented standard deviation change in the independent variable. These estimates allowed comparisons of effect sizes across independent variables.

Data Collection Summary:

Timing of Measurements

Phase one of the Healthy Passages study
Data collected between May and September 2003.

Dependent Variables

Physical activity
Obesity status

Independent Variables

Latent variables for the physical and social environments.

Control Variables

Sociodemographic factors.

Description of Actual Data Sample:

Initial N: 1,848 fifth-grade students from 21 schools
Attrition (final N):
- The parents of 1,059 (57%) students gave written permission to be contacted about the study
- Because the time for data collection was limited, only 871 (82%) families were fully pursued
- A total of 650 (75%) families completed both the parent and child interviews
- 55% were females
Age: 11.30 (0.51) years, with a minimum of 10 years and maximum of 14 years
Ethnicity:
- 236 non-Hispanic blacks
- 205 Hispanics
- 157 non-Hispanic whites
- 52 members of other non-Hispanic racial or ethnic group
- Hispanic: 30%
- Black: 38%
- Other: 25%
Other relevant demographics:
- The majority of participants lived in urban areas
- Parental educational attainments, score on scale: 3.12 (1.71), with 3 = some college
- Household income: $34,650 ($25,150); minimum was less than 5,000, maximum was more than 250,000
- 58% had two parents at home
Anthropometrics:
- BMI of 21.21 (5.20), with minimum of 13.19 and maximum of 43.61
- Underweight/normal weight: 59%
- Overweight: 16%
- Obese: 25%
Location:
- Houston, TX: 29%
- Birmingham, AL: 32%
- Los Angeles, CA: 39%.

Summary of Results:

Key Findings

The children reported, on average, doing vigorous exercise approximately four days a week, participating in physical education in school three days a week and participating in two to three sports teams
Fit of the data to the measurement model was good
- Comparative fit index=0.95
- Root mean square error of approximation=0.05
- Standardized root mean square residual=0.05
All the social environment indicators were significant in the expected direction, with higher values of the latent variable implying a more favorable social environment
All the physical environment indicators were also significant. Higher values of the latent variable implied a more favorable physical environment for physical activity. The correlation between the latent variables was -0.09 (P<0.05).
Hispanic and black children had lower overall physical activity than did white children after other factors were taken into consideration
A favorable neighborhood social environment was positively associated with overall physical activity, days of vigorous exercise, days with physical education in school, and favoring free-time movement activities
The physical environment was not significantly associated with any measure of physical activity
Neighborhood physical environment had no significant association with activity levels in the structural equation modeling
A favorable social environment was positively associated with physical activity, which was negatively associated with child obesity after controlling for individual sociodemographic factors
The model with obesity status measured as a binary variable (underweight or normal weight vs, overweight or obese) and the model for child BMI provided very similar results that were not shown in the article.

Individual and Neighborhood Characteristics of Fifth-grade Students: Healthy Passages Phase 1: 2003

Physical Activity	Mean (SD) or Percentage	Minimum	Maximum
Vigorous exercise, days per week	3.80 (2.39)	0	7
Moderate exercise, days per week	2.32 (2.15)	0	7
Physical education or gym class, days per week	2.91 (1.92)	0	5
Sports participation, no teams	2.66 (1.18)	1	4
Physical active free-time activities	1.86 (0.69)	1	3
Participation in other physical activity or lessons	42
Walking or biking to school	18

Other Findings

On average, neighborhood residents in this study met with friends approximately two or three times a month but interacted with neighbors "rarely" to "sometimes"
Parents rated their neighborhood as somewhat safe on average, typically reporting that walking alone after dark was "somewhat dangerous" to "fairly safe"
Traffic generally light
Face-blocks were somewhat disorderly, with 82% having litter and approximately 40% having graffiti
Most neighborhoods were primarily residential.

Author Conclusion:

The findings suggest that neighborhood social factors as well as the physical environment should be considered in the development of health policy and interventions to reduce childhood obesity.

Funding Source:

Government:

CDC Coop agreements CCU409679, CCU609653, CCU915773

Reviewer Comments:

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?	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?	???
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?	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?		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?	No
	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?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	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?	Yes
	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?	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?	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?	N/A
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