www.iihs.org
Effects of Booster Seat Laws on Injury Risk Among Children in Crashes Transportation Research Board 91st Annual Meeting, Occupant Protection Committee Washington, DC● January 24, 2012 Angela H. Eichelberger, Ph.D.
Angela H. Eichelberger
Effects of Booster Seat Laws
Co-authors
Aline O. Chouinard Jessica S. Jermakian
www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
Page 2 of 17
Angela H. Eichelberger
Effects of Booster Seat Laws
Boosters can improve 3-point belt fit
www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Percentage of children 4-8 reported as using child safety seats Motor Vehicle Occupant Safety Survey, 2000-07 100 forward-facing with harness 80
highback or backless booster
60
40
20
0 2000
2003
2007 www.iihs.org
Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Percentage of children 4-7 observed using child safety seats National Survey on the Use of Booster Seats, 2006-09 100 forward-facing with harness 80
highback or backless booster
60
40
20
0 2006
2007
2008
2009 www.iihs.org
Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Enactment of booster seat laws in the U.S.
effective year
cumulative number of states
2001
5
2002
10
2003
18
2004
26
2005
34
2006
38
2007
39
2008
43
2009 to date
47
www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Child restraint or booster seat laws in the U.S. December 2011
WA
NH
ND
MT
VT MN
SD
OR
ID
ME
WI
WY
NY
MI
IA NE IL NV
UT
CO
KS
PA
OH
IN
NJ
MO
WV KY
CA
NC
AR
NM
DC
SC MS
TX
DE
VA
RI CT
MD
TN
OK AZ
MA
AL
LA
GA
3 & younger 4 & younger FL
AK
5 & younger 6 & younger 7 & younger 8 & younger
HI
www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Prior research on effectiveness of booster seat laws • Effects on restraint use – Children 4-7 were 39 percent more likely to use boosters or child restraints in U.S. states with booster seat laws than in states without laws – Booster use increased after laws amended in the following U.S. states: Wisconsin, Tennessee, and New York
• Effects on injuries – Children 3-8 who were covered by laws were less likely to be hospitalized for motor vehicle injuries than children not covered by laws – In New York State, the per capita injury rate before and after the booster seat law decreased 18 percent among 4-6 year-olds www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Study objectives and methods • To examine changes in the per capita rates of – Restraint use of children in crashes – Rear seat use of children in crashes – Children injured in crashes
• Before-after design with comparison group (ages 9-12) – Change in per capita rates among booster-age children before and after law changes Adjusted rate ratio = O / E – O is the number of booster-age children using child seats, rear seats, or injured in crashes after law changes – E is the expected number of booster-age children using child seats, rear seats, or injured in crashes after law changes, adjusted for changes in comparison group www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Data sources
• State Data System (SDS) – Collection of state crash files coded from police crash reports in the United States – Injury severity, restraint use, and seating position for children who were vehicle occupants in crashes
– States were chosen based on whether amended laws covered children through at least age 7, and 2 years of data were available before and after law change
• U.S. Census Bureau population data – Estimates by single years of age used to calculate population-based rates
www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Study states Age groups required to use child restraints or booster seats
affected by law change
state
prior law
new law
Missouri, Pennsylvania, and Wisconsin
3 and younger
7 and younger
4-7
North Carolina
4 and younger
7 and younger
5-7
Wyoming
4 and younger
8 and younger
5-8
www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
Page 11 of 17
Angela H. Eichelberger
Effects of Booster Seat Laws
Percent of restraint use among children in crashes before and after law changes Five study states combined seat belt only
100
child safety seat (harness or booster) 80
1
2
87
86
before law
after law
17 50
60
40
73 42
20
0 before law
after law
children ages 4-8 targeted by law upgrades
comparison group of children ages 9-12 www.iihs.org
Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Percent of front- and rear-seating among children in crashes before and after laws Five study states combined 100 10 18 80
36
33
60
63
60
40
88 78
20 rear seat
front seat
0 before law
after law
children ages 4-8 targeted by law upgrades
before law
after law
comparison group of children ages 9-12 www.iihs.org
Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Changes in child safety seat use and rear seating in booster-age children in crashes Five study states combined
booster-age children using…
adjusted rate ratio (95% CI)
observed
expected
child safety seats (harness or booster)
31,557
10,862
2.91 (2.84-2.97)
rear seats
55,856
52,759
1.06 (1.05-1.07)
www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Observed and expected booster-age children injured during the 2 years after the law changes Five study states combined
injury severity
observed
expected
adjusted rate ratio (95% CI)
all injured children
8,995
9,469
0.95 (0.92-0.98)
children with fatal or incapacitating injuries
345
413
0.83 (0.72-0.97)
www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
Effects of Booster Seat Laws
Conclusions
• Amendments to existing child restraint laws adding a booster seat requirement appear to be effective in the United States • Among children covered by laws – Use of child safety seats increased – Placement of children in rear seats increased – Injuries were reduced, particularly serious injuries
www.iihs.org Presented January 24, 2012 at the TRB ANB45 Annual Meeting
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Angela H. Eichelberger
www.iihs.org
Presented January 24, 2012 at the TRB ANB45 Annual Meeting
Effects of Booster Seat Laws
Dedicated to reducing deaths, injuries, and property damage on the highway
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