PWM: Environment (2012)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To examine the associations between pediatric overweight in low-income preschool children and three environmental factors: 

  • Proximity of playgrounds
  • Proximity of fast food restaurants
  • Neighborhood safety.
Inclusion Criteria:
  • Enrolled in a WIC program
  • Made at least one WIC visit between January 1, 1998 and June 20, 2001
  • Resident of Cincinnati, OH
  • Between 36 and 59 months of age at WIC visit.
Exclusion Criteria:

None specified.

Description of Study Protocol:

Recruitment

  • Children between 36 and 59 months of age were selected from those who had visited one of 14 Cincinnati, OH, WIC clinics or one of four WIC clinics in the county surrounding Cincinnati (N=11,246)
  • This list was limited to those who had addresses that could be geocoded to a location in the city or surrounding county (N=10,161)
  • Of these the children living in one of 46 neighborhoods for which crime statistics were available were included in the study (N=7,020).

Design

A program (ArcViewTM) spatially located the home residence of the each subject and the walking distance to the nearest playground and fast food restaurant. Each home, playground and restaurant were located in one of 46 neighborhoods for which crime statistics were known.

Statistical Analysis

  • Crime rate variables were transformed into categorical variables and children were divided into quintiles according to the crime rate and 911 call rate in their neighborhood
  • T-test statistics compared the mean distance to the nearest playground and nearest fast food restaurant in overweight and non-overweight children
  • Chi-square tests compared the prevalence of overweight among children living in neighborhoods with and without fast food restaurants and with and without public playgrounds, and across the quintiles of crime and 911 calls
  • Pearson correlation coefficient between each child's BMI z-score and playground and fast food distance
  • Logistic regression models with overweight as the dependent variable:
    • Crime rate by playground distance
    • Child sex by playground distance
    • Poverty ratio by fast food distance
    • Child race by fast food distance
    • Child race by crime rate
    • Poverty ratio by crime rate
  • Multi-variable logistic regression model to determine the independent odds of child overweight associated with the three environmental factors adjusting for household income, child race and child sex. 
Data Collection Summary:

Timing of Measurements

  • Crime statistics were from 1999
  • Restaurant locations were from 2001 telephone book.

Dependent Variables

  • BMI: Calculated from height and weight at most recent WIC visit; weight obtained in light clothing without shoes
  • Overweight status: BMI more than 95th percentile for age and sex.

Independent Variables

  • Proximity of playgrounds: Addresses of 394 playgrounds obtained from county health department
  • Proximity of fast food restaurants: Researchers used nationwide or multi-state chains with more than one store in Cincinnati, that served complete meals without the assistance of waiters or waitresses, and had facilities for consuming food onsite. Restaurants and numbers included in the data analysis were:
    • McDonalds (31)
    • Wendy's (28)
    • Arby's (18)
    • Burger King (17)
    • White Castle (15)
    • Taco Bell (15)
    • KFC (16)
    • Rally's (11)
  • Neighborhood safety: Rates per 1,000 population per year for two variables: 
    • Number of serious crimes (murder, rape, robbery, burglary, aggravated assault, larceny, auto theft)
    • Number of 911 calls. 

Control Variables

  • Child race
  • Child sex
  • Family income.
Description of Actual Data Sample:
  • Initial N: 7,020 children
  • Attrition (final N): 7,020 children
  • Age: Mean 50±7 months
  • Ethnicity: 76% black and 23% white; poverty ratio was significantly higher for black children (P<0.001)
  • Anthropometrics: 9.2% of children had a BMI 95th percentile or more; 21.2% had a BMI 85th percentile or higher
  • Location: United States.
Summary of Results:

Key Findings

Mean Distance from Child Residence to Nearest Playground and Fast Food Restaurant by Child BMI

Variables

BMI 95th Percentile or Higher BMI 95th Percentile or Lower

P- value

Playground distance, miles

0.31 0.31 0.77

Fast food distance, miles

0.70 0.69 0.91

 

Percentage of Children Defined as Overweight and Neighborhood Safety

  Quintiles of crime rate P-value
 

1st

(Lowest)

2nd 3rd 4th 5th  
Percent BMI 95th percentile or higher

8.6

8.8 10.1 9.0 9.7 0.64
Percent BMI 85th percentile or higher 20.4 19.1 22.5 21.5 22.6 0.1
  Quintiles of 911 call rate  
Percent BMI 95th percentile or less 10.7 8.0 7.9 10.1 9.4 0.04
Percent BMI 85th percentile or less 22.7 19.6 18.8 22.7 22.1 0.02

Other Findings

  • No difference in mean distance to the nearest playground or fast food restaurant by BMI using cutoffs of either the 95th or 85th percentile
  • No correlation between BMI z-scores and distance to playground or fast food restaurant
  • Poverty ratio was higher in overweight than in non-overweight children (0.71 vs. 0.67, P=0.03)
  • Poverty ratio was correlated with playground proximity (R= 0.12, P<0.001) and fast food proximity (R=-0.03, P=0.0007)
  • Poverty ratio increased across the quintiles of neighborhood crime, ranging from 0.80 in the lowest crime quintile to 0.56 in the highest quintile (P<0.001)
  • Multi-variate logistic regression models showed no associations between childhood overweight and environmental variables after controlling for poverty ratio, race and sex.
Author Conclusion:

This study found no association between overweight and measures of neighborhood safety, proximity of fast food restaurants or proximity of playgrounds in urban, low-income, pre-school children.

 

Funding Source:
Government: USDA
Reviewer Comments:

The authors noted that there was lack of variation in the variables examined. This could explain null associations in this study. 

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? N/A
  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? 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? N/A
  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? Yes
  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.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  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? 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? 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