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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

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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
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
injury traumatic
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
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
Injury Categorization
  • Mechanism
  • Intent (unintentional and intentional)
  • Place of occurrence
  • And by nature and severity
childhood injuries
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 injuries
Epidemiological Framework for Injuries


Agent & vector

Environment: social and physical

haddon s matrix
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 matrix12

Agent and Carrier


Physical Social

Haddon’s Matrix




  • 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.
  • 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
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
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
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
  • 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)
  • 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)
  • 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
Study Limitations
  • Limits in generalizability
  • Reporting bias
  • Recall bias
implications for injury prevention
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
Built Environment




Urban and rural environments

Domestic and global

physical inactivity
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
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
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
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
How Crime May Influence Physical Activity


Physical Activity

Crime &Disorder

Fear of Crime &Disorder



(e.g., time of day, lighting, etc)




active living research round 8
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
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
  • 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
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
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
what does it mean issues to consider
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
Integrating Childhood Obesity and Injury
  • Pollack KM. An Injury Prevention Perspective on the Childhood Obesity Epidemic. Preventing Chronic Disease, 2009; 6(3):\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
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
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
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, 7am-1pm
  • San Francisco, Portland, Cambridge
concluding thoughts
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: place-based policies
guest editorial injury prevention 2003
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