Childhood Obesity and Injury:
Research connecting childhood obesity and
injury risk
Keshia M. Pollack, PhD, MPH
Assistant Professor
Leon Robertson Career Development Chair in Injury Prevention
Department of Health Policy and Management
Johns Hopkins Bloomberg School of Public Health
July 14, 2009
Presentation Overview
● Introduce some key concepts in injury prevention and
control
● Present research exploring obesity as a risk factor for
injury
● Present research on how injuries and other hazards in
the built environment impact walking to school
● Provide recommendations on how to better integrate
injury prevention and control principles with childhood
obesity prevention efforts
Short course in injury concepts…
Injury (Traumatic)
● Injuries ARE NOT accidents; they are preventable!
● Injury refers to damage to cells and organs from energy
exposures that have relatively sudden, discernible
effects
● Results from an acute exposure to physical agents such
as mechanical energy, heat, electricity, chemicals,
ionizing radiation in amounts or at rates above or below
the threshold of human tolerance
Epidemiology of Injuries
● Leading cause of death ages 1 to 44
● Leading cause of years of potential life lost before 65 yrs
● 33% of all ED visits and 8% of hospital admissions
● Disparities: socio-demographic factors
● Injuries are costly
 Direct costs - $80.2 billion
 Productivity losses - $326 billion
Injury Categorization
● Mechanism
● Intent (unintentional and intentional)
● Place of occurrence
● And by nature and severity
Childhood Injuries
● Injuries are the leading cause of ED visits and hospital
admissions for children
● Leading cause of death for children
● Leading causes of injury death:
 Motor vehicle crashes
 Drowning
 Falls
 Burns
 Poisonings
 Firearms
● Global issue
Epidemiological Framework for Infectious Diseases
Host
Agent & vector
Environment
Epidemiological Framework for Injuries
Host
Agent & vector
Environment: social and physical
Haddon’s Matrix
● William Haddon Jr. (1968, 1980)
● The Haddon Phase-Factor Matrix
● The Haddon Factors
 Human (individual) factors
 Agent and carrier factors
 Environmental factors
Haddon’s Matrix
Human
Agent and
Carrier
Environment
Physical
PreEvent
Event
PostEvent
Social
Obesity as a risk factor for injury
Acknowledgements
● Co-authors: Dawei Xie, PhD, Kristy Arbogast, PhD,
and Dennis Durbin, MD, MSCE
● State Farm Mutual Automobile Insurance Company
● Supported in part by Grant Number 5R49CE3000198
from the CDC.
● Body Mass Index and Injury Risk Among U.S.
Children 9-15 Years Old in Motor Vehicle Crashes.
Injury Prevention 2008; 14(6):372-76.
Background
● MVCs are the leading cause of death and a leading
cause of nonfatal injuries for youth
● Association between childhood obesity and certain
pediatric injuries
● Childhood obesity public health epidemic
● Some adult data on the association between obesity and
MVC-related injury; limited research has explored this
issue for youth
Research Aims and Hypotheses
● Determine the relationship between child body mass
index (BMI) and the risk of injury resulting from
MVCs to older children in the U.S.
● Hypotheses:
 After adjusting for potential confounders, BMI
would be significantly associated with the risk of
injury
 Distribution of body region injured would vary by
BMI
Study Sample
● Partners for Child Passenger Safety (PCPS) study
● 12/1/00 and 12/31/06
● Included: vehicles with older children, b/w 9 & 15
years, whose driver was their parent/guardian
● Excluded: children less than 5 feet tall and with missing
weight or height
Measures and Analysis
● Child obesity: BMI, CDC criteria
● Injury: parent-reported Abbreviated Injury Severity
(AIS) 2+
● Covariates: vehicle model years, airbag deployed, age,
child seating position, vehicle type, child restraint use,
crash severity: intrusion and rollover, direction of
impact
● Multivariate Logistic Regression
Findings
● 3,232 children in 2,873 vehicles, which represented
population estimates of 54,616 children in 49,037
vehicles
● 15% (n=500) sustained AIS score of 2+ injury
● No overall significant increased risk of injury (any
body part) by BMI;
 Overweight: OR 1.34 (0.70, 2.55)
 Obese: OR 1.03 (0.54, 1.94)
Findings
● No significant increased injury risk to the head
● Yes, significant increased injury risk to the lower and
upper extremities (fractures)
 Underweight: OR 0.77 (0.20, 2.86)
 Overweight: OR 2.46 (1.46, 4.77)
 Obese: OR 2.54 (1.15, 5.59)
Figure 1. Distribution of upper extremity fractures by overweight status
100%
90%
Percent
80%
70%
Shoulder
60%
Scapula
Clavicle
50%
Elbow
40%
Forearm
30%
Hand
20%
10%
0%
Underweight/normal
Overweight
Overweight status
Obese
Figure 2. Distribution of lower extremity fractures by child overweight status
100%
90%
80%
Percent
70%
Pelvis
Femur/knee
60%
50%
Ankle
40%
Foot
30%
20%
10%
0%
Underweight/normal
Overweight
Overweight category
Obese
Conclusions
● Confirmed the overwhelming effects of previously
identified risk factors for pediatric MVC-related
injuries: riding in an older car, sitting in the front row,
being unrestrained, and being in a severe crash
● Child overweight and obesity is a risk factor for injury
to the extremities
Study Limitations
● Limits in generalizability
● Reporting bias
● Recall bias
Implications for Injury Prevention
● The increased risk of injury to the extremities for
overweight and obese children in crashes may be due to
a combination of physiology, biomechanical forces, and
vehicle design.
 Biomechanics + kinetic energy
 Physiology
 Design
Built Environment, Injury, and Physical
Inactivity in Children
Built Environment
Live
Learn
Play
Urban and rural environments
Domestic and global
Physical Inactivity
● Energy expenditure
● High levels of inactivity among children
● Sedentary lifestyle affects health
● Significant benefits of physical activity and play for
children
● Most cited barriers to being physically active?
Ecological Model for Health
● Natural synergies with concept of the built environment
● Disregards the traditional view of obesity as a personal
disorder that requires treatment
● Regards obesity as a normal response to an abnormal
environment, rather than vice versa
● Need to understand, measure, and alter the
"obesogenic" environment
Built Environment and Injury Hazards
● Transportation: pedestrian, bicycle
● Injury risks during play: sports, playgrounds
● Physical and social environment: incivilities
● Violence and crime
Violence and the Community
● Homicide rates have been on the rise in U.S. cities
● Violence linked to fear
● Fear linked to inactivity, stress, smoking, etc
● Impact on physical activity?
 Perceived and actual fear?
 Rates of violence: property crime, homicide, assaults, etc.
 Does type of crime matter
How Crime May Influence Physical Activity
Crime &
Disorder
Situational
Characteristics
(e.g., time of day,
lighting, etc)
Fear of
Crime &
Disorder
Interpersonal/
Intrapersonal
characteristics
Outdoor
Physical
Activity
Active Living Research, Round 8
● Exploring the Impact of the Urban Environment and
Collective Efficacy on Child Activity and Anthropometry
● Grant period: 1/1/09 – 6/30/10
● Interdisciplinary team
 Dr. Pollack (injury epidemiology, obesity)
 Dr. Frank Curriero (GIS and spatial stats)
 Mr. Tim Shields (GIS)
 Dr. Michele Cooley (youth, violence, development)
 Dr. Debra Furr-Holden (alcohol, drug, env measurement)
 Dr. Daniel Webster (violence epidemiologist)
 Dr. Caterina Roman (criminologist)
Research Questions
● What at the key factors in the social and physical urban
environment that are associated with child activity and
anthropometry?
● Outcomes:
 Walking to school (also have to bus stop)
 BMI and waist-to-hip ratio
 Use of street for play
Data
● NIfETy
 Neighborhood Inventory for Environmental Typology
 78 items, 7 domains: using only physical and social
disorder
 Rated over 1000 block faces
● MORE project
 Multiple Opportunities To Reach Excellence
 Parents and child perceptions and behaviors, objective
anthropometic measures
● Baltimore City Data Collaborative
● Baltimore City Police Department
● U.S. Census
Study Sample (n=365 children)
● 86% Black
● 46% Males
● Median household income $32K
● Parent education: most high school or less
● Distance to school: median .32 miles
● 56% walk most of the time
Neighborhood Incivilities
● Example: total broken windows, # abandoned houses,
trash in street or alley, graffiti, inoperable vehicles,
crack pipes, cigarette butts or marijuana roaches, liquor
bars and stores, used condoms, shell casings
● Present or not
● Summary score for binary items
● Each block rated as high or low incivilities
Partial results from adjusted GEE logistic regression
model (odds of walking to school)
Variables
Odds Ratio
95% CI
Age
1.02
1.00 – 1.04
Male
1.26
0.74 – 2.16
Distance to school
0.02
0.01 – 0.15
Child perceived safe neighborhood
0.91
0.58 – 1.40
Median household income (neighborhood)
0.88
0.79 – 0.98
Incivilities (above median)
3.15
1.52 – 6.51
What Does it Mean/Issues to Consider
● Findings spurious?
● GEE account for schools, only accounted for
neighborhood clustering
● Incivilities measure of neighborhood SES or truly
measure of the environment?
● No info on car ownership: suggestion to use %
employed as proxy since driving to school depends on
work schedule
● School SES – need to include
● Quality of playgrounds – may include
● More analysis!!!
Integrating Childhood Obesity and Injury
● Pollack KM. An Injury Prevention Perspective on the
Childhood Obesity Epidemic. Preventing Chronic
Disease, 2009; 6(3):
http://www.cdc.gov/pcd/issues/2009/\jul/08_0258.htm
● Injury prevention and childhood obesity prevention
● Two examples of synergy:
 Playground-related injuries
 Safe Routes to School
Areas for Future Research (Pollack 2009)
● Document childhood injuries during physical activity
● Investigate the risk and distribution of injury in studies
of access and opportunities for places for youth to
engage in physical activity.
● Explore the implications of obesity for safety
equipment fit and availability
Implications for Prevention Policy
● Intentional injury (crime and violence)
 Focus on the worst places first e.g. “Hot Spots
Policing” or Problem Oriented Policing
 Conduct analysis of place
 Crime Prevention Through Environmental Design
(CPTED)
 Engage community and key stakeholders
● Unintentional injury
 “Safe Zones” – violence and traffic free
Bogota, Columbia – Ciclovia
● Every Sunday, for 7
hours, 81 miles of city
are closed to traffic
● Residents walk, bike,
skate, etc.
● NYC 2008, 7 miles on
three Saturdays, 7am1pm
● San Francisco,
Portland, Cambridge
Policies Related to Youth Physical Activity
Concluding Thoughts
● Obesity + physical activity + safety/injury
● All children need access to safe, accessible, and
affordable places to play, not just places to play
● Built environment literature pays homage to safety, but
not enough
● Include injury prevention and control concepts
● Translate epidemiological evidence to policy: placebased policies
Guest Editorial Injury Prevention (2003)
“Increasing the level of physical activity in
children and adults is a pressing public health
concern; however, the injuries resulting from
sports and recreational activities are also a
grave concern…responsibility rests on the
shoulders on injury control professionals to
minimize the risk of injury…while maximizing
the public health gain from prevention of
obesity and other inactivity related disease.”
- SW Marshall, KM Guskiewicz
Contact information: kpollack@jhsph.edu or 410-502-6272