EAL

PWM: Environment (2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The aim of this study was to explore the role of multiple built environment variables on childhood obesity.

Inclusion Criteria:

Children ages 24 months to 18 years
Seen at an outpatient facility (Partners Health Care) between January 1 and December 31 2006
Residing in Massachusetts.

Exclusion Criteria:

Those without a recorded weight and height on the visit day
Those with BMI <10 or> 50 (biologically implausible)
Missing any part of home address.

Description of Study Protocol:

Recruitment

Subjects were selected via a query of the Partners Health Care database

Design

Subjects's BMI percentile was compared to the availability of the built environment (streets, sidewalks, schools, subway stations, bicycle paths, open spaces, fast food restaurants, population density, and crime).

Blinding used

None

Intervention

None

Statistical Analysis

T-test was used to examine bivariate relationships of the built and social environment variables with overweight and non-overweight as as well as obese and non-obese children. The odds ratio (OR) with 95% confidence intervals (CIs) for being overweight or obese for those built environment
variables was calculated. Multilevel logistic regression models for each of the built environment variables with the dependent variable categorized above or below either the 85th or 95th percentile.

Data Collection Summary:

Timing of Measurements

Measurements were taken at one point in time (outpatient visit).

Dependent Variables

Availability of eight characteristics of the built environment (streets, sidewalks, schools, subway stations, bicycle paths, open spaces, fast food restaurants, population density and crime). This was done using Geographic Information Systems (GIS). Availability was considered to be a 400-meter radius for the density of subway stations, fast food restaurants, and bicycle paths. Two miles was considered to be the walkable buffer zone for schools.

Independent Variable

Overweight (BMI ≥85th percentile) or obese (BMI ≥95th percentile)

Control Variables

Age, enrollment in Partners Health Care

Description of Actual Data Sample:

Initial N: 21,008
Attrition (final N):
- 51.5% male
- 48.5% female
Age: 9.3±4.8 years
Ethnicity:
- 53.8% white
- 7.4% black
- 25.6% Hispanic
- 5.5% Asian
- 7.4% other
Other relevant demographics: 22.2 % boys were obese, 18.1% girls
Anthropometrics:

Percent of each group with BMI ≥ 85th percentile		Percent of each group with BMI ≥ 95th percentile
Whites	31.5	Whites	16
Black	40.9	Black	22.5
Hispanic	49.8	Hispanic	30.7
Asian	28.0	Asian	13.0
Other	33.2	Other	18.0

Location: 300 towns throughout Massachusetts with urban areas around metropolitan Boston most heavily represented.

Summary of Results:

Key Findings

Overweight children lived closer to fast food restaurants, subway stops and schools (P<0.001).

Overweight was associated with an increased density of fast-food restaurants, (P=0.01) and fewer subway stops (P=0.002). Overweight and obesity was associated with higher crime rates (P<0.0001 for both) and population density (P=0.003 for overweight and P=0.0002 for obesity). When adjusting for age, gender, race and income, only the density of subway stops remained significant (OR=0.85, CI=0.76-0.95).

Adjusting for sociodemographic features only the presence of subway stations within 400m was associated with reduced risk for overweight.

Author Conclusion:

An increased number of subway stations was associated with a lower BMI in children. To our knowledge this is the first study to correlate childhood BMI with sidewalk access and public transportation.

Funding Source:

University/Hospital:

Department of Pediatrics , Mass General Hospital, Boston MA

Reviewer Comments:

Large study, used GIS mapping to identify built environment. Discussed limitations well.

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)	Yes
	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)	Yes

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?	???
	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.)	Yes
	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?	Yes
	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.)	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?		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?	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?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	???
	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)?	???
	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