- Topic Submission
- Discussion & Evaluation
- Development
- Project
Social & Cultural
Traffic Safety
Is this related to or a continuation of a previous Iowa DOT research project?
No
Does this idea include matching funds?
No
Anticipated Benefits
Comparison of costs for occupants who are belted and not belted and the financial burden of the injuries by payer (e.g., private insurance, Medicare, Medicaid, self-insured, uninsured).
Focus Area
Safety
Research Program
SPR / 774: Research & Technology Transfer
Project Title
Estimating the Costs of Traumatic Injuries to Unbelted Occupants in Motor Vehicle Crashes
Project Number
17-SPR0-011
Contracted Agency
University of Iowa
Project Champion
Funding Program
State Planning and Research
Project Funding
$72,000
Project Funding Including External Sources
$72,000
Project Start Date
07/01/2017
Current Project End Date
01/31/2022
Project Abstract
To our knowledge, the only in-depth analysis of the effect of seat belt use on cost of motor vehicle injuries in Iowa was conducted 30 years ago, just after the safety belt law was enacted in 1986. At that time, about half those injured were not belted, yet their injuries accounted for 78% of the costs. The mean hospital costs for those who were not belted were 3.6 times higher than those who were belted and more persons who were not belted were uninsured or covered by Medicaid.
This project aims to estimate the costs of traumatic injuries suffered by adult occupants in motor vehicle crashes in Iowa from 2012 to 2016. The analysis will compare costs for occupants who are belted and not belted and also examine the financial burden of the injuries by payer (e.g., private insurance, Medicare, Medicaid, self-insured, uninsured). The analysis will also consider the effects of different crash, vehicle, and occupant characteristics, for example, seating position (i.e., driver vs. passenger, front seat vs. rear seat), number of vehicles, vehicle type, manner of crash or collision, number of occupants in the vehicles, location, or alcohol/drug involvement, on costs of injuries for unbelted occupants.
This project aims to estimate the costs of traumatic injuries suffered by adult occupants in motor vehicle crashes in Iowa from 2012 to 2016. The analysis will compare costs for occupants who are belted and not belted and also examine the financial burden of the injuries by payer (e.g., private insurance, Medicare, Medicaid, self-insured, uninsured). The analysis will also consider the effects of different crash, vehicle, and occupant characteristics, for example, seating position (i.e., driver vs. passenger, front seat vs. rear seat), number of vehicles, vehicle type, manner of crash or collision, number of occupants in the vehicles, location, or alcohol/drug involvement, on costs of injuries for unbelted occupants.
Project Complete Date
01/31/2022
Project Deliverables
Final Report Abstract
The use of seat belts by back-seat occupants have been estimated to reduce crash fatalities in passenger cars by 60% and in light trucks by 70% (Zhu, Cummings, Chu, & Cook, 2007). Since 1986, the State of Iowa has required occupants in the front seat to use seat belts, but passengers age 18 and older are not required to buckle up when they ride in the back seat. In 2021, the observed belt use rate for the front seat was 92.8% (Allen, Fox, & Berg, 2021). However, only 35% of Iowans surveyed about their seat belt use reported that they always use a belt in the back seat (Reyes, Marshall, & McGehee, 2015). Only 23.1% of adult rear-seat passengers involved in fatal crashes in Iowa from 2013-2019 were belted compared to 70.5% of adult front-seat passengers.
One way to quantify the impact of seat belts is to consider the costs of treating injuries due to motor vehicle crashes. NHTSA estimated that medical costs represent about 25% of the total costs associated with non-fatal motor vehicle crash injuries (Blincoe et al., 2002). An analysis of the hospital costs associated with motor vehicle crash injuries in Nebraska found that the use of a lap-shoulder seat belt resulted in 85% lower hospital costs (Han, Newmyer, & Qu, 2017).
At the outset, this project aimed to estimate the costs of traumatic injuries suffered by adult rear-seat occupants in motor vehicle crashes in Iowa and to compare costs for occupants who were reported to be belted and not belted for crashes from 2012 through 2016. Obtaining data from the State Trauma Registry, which is administered by the Iowa Department of Public Health, proved to be a challenging process even prior to the COVID-19 pandemic. In 2021 another source of data for cost of motor vehicle crash injuries was identified, and the years of analysis were updated to 2016 through 2019.
The new dataset was obtained from the University of Iowa Injury Prevention Research Center. It contained Iowa emergency room and inpatient hospital data that had been probabilistically linked to injured individuals in the Iowa crash data. However, as this analysis was conducted, concerns were raised about the data linkage process, and there is low confidence in the quality of the data linkage. Therefore, all results relating to the costs of injuries and other hospital outcomes reported herein should be considered to be preliminary findings.
From 2016-2019, a total of 1,646 adult occupants seated in rear positions in passenger vehicles who were reported to be injured were identified from the Iowa crash data system. Of these, 1,502 were probabilistically linked to a person in the hospital data. Ordinal regression models were used to calculate odds ratios for seat belt use while controlling for occupant age and gender, vehicle damage, speed limit, crash type, intersection, rural location, time of day, and the presence of alcohol or drugs in at least one driver’s system during the crash.
For injured adult occupants in the rear seat, not using a seat belt was associated with more severe injuries. Specifically, these occupants were 6.2 times more likely to have a fatal injury compared to lower levels of injury and 3.6 times more likely to have a fatal or suspected serious/incapacitating injury compared to a suspected minor/non-incapacitating or possible injury. Additionally occupants were 1.9 times more likely to receive a higher level of transport to medical care (i.e., EMS transport versus nonEMS transport versus not transported) compared to those who were belted. Two thirds of injured adult occupants in the rear seat were younger than age 40. A total of 1,892 years of potential life (relative to an expected age of 80) were lost due to fatal injuries. After controlling for gender and crash 2 characteristics, the unbelted occupants (n = 34) lost significantly more years of potential life, on average, than the belted occupants (n = 8).
Analysis of total hospital inpatient and emergency room charges found no significant differences by seat belt use status. This was not the anticipated finding based on similar analyses in the literature and is just one of several reasons for low confidence in the quality of the linkage between the crash and hospital data. Nevertheless, this analysis did show that seat belt use significantly reduces the risk of fatal and severe injury for rear-seat adult passengers injured in motor vehicle crashes and provides Iowa-specific information for safety messages to promote seat belt use.
One way to quantify the impact of seat belts is to consider the costs of treating injuries due to motor vehicle crashes. NHTSA estimated that medical costs represent about 25% of the total costs associated with non-fatal motor vehicle crash injuries (Blincoe et al., 2002). An analysis of the hospital costs associated with motor vehicle crash injuries in Nebraska found that the use of a lap-shoulder seat belt resulted in 85% lower hospital costs (Han, Newmyer, & Qu, 2017).
At the outset, this project aimed to estimate the costs of traumatic injuries suffered by adult rear-seat occupants in motor vehicle crashes in Iowa and to compare costs for occupants who were reported to be belted and not belted for crashes from 2012 through 2016. Obtaining data from the State Trauma Registry, which is administered by the Iowa Department of Public Health, proved to be a challenging process even prior to the COVID-19 pandemic. In 2021 another source of data for cost of motor vehicle crash injuries was identified, and the years of analysis were updated to 2016 through 2019.
The new dataset was obtained from the University of Iowa Injury Prevention Research Center. It contained Iowa emergency room and inpatient hospital data that had been probabilistically linked to injured individuals in the Iowa crash data. However, as this analysis was conducted, concerns were raised about the data linkage process, and there is low confidence in the quality of the data linkage. Therefore, all results relating to the costs of injuries and other hospital outcomes reported herein should be considered to be preliminary findings.
From 2016-2019, a total of 1,646 adult occupants seated in rear positions in passenger vehicles who were reported to be injured were identified from the Iowa crash data system. Of these, 1,502 were probabilistically linked to a person in the hospital data. Ordinal regression models were used to calculate odds ratios for seat belt use while controlling for occupant age and gender, vehicle damage, speed limit, crash type, intersection, rural location, time of day, and the presence of alcohol or drugs in at least one driver’s system during the crash.
For injured adult occupants in the rear seat, not using a seat belt was associated with more severe injuries. Specifically, these occupants were 6.2 times more likely to have a fatal injury compared to lower levels of injury and 3.6 times more likely to have a fatal or suspected serious/incapacitating injury compared to a suspected minor/non-incapacitating or possible injury. Additionally occupants were 1.9 times more likely to receive a higher level of transport to medical care (i.e., EMS transport versus nonEMS transport versus not transported) compared to those who were belted. Two thirds of injured adult occupants in the rear seat were younger than age 40. A total of 1,892 years of potential life (relative to an expected age of 80) were lost due to fatal injuries. After controlling for gender and crash 2 characteristics, the unbelted occupants (n = 34) lost significantly more years of potential life, on average, than the belted occupants (n = 8).
Analysis of total hospital inpatient and emergency room charges found no significant differences by seat belt use status. This was not the anticipated finding based on similar analyses in the literature and is just one of several reasons for low confidence in the quality of the linkage between the crash and hospital data. Nevertheless, this analysis did show that seat belt use significantly reduces the risk of fatal and severe injury for rear-seat adult passengers injured in motor vehicle crashes and provides Iowa-specific information for safety messages to promote seat belt use.
Project Champion
Technical Advisory Committee
Project Manager
Delivering targeted solutions for Iowa's transportation future.
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