Introduction
Policies that allow directly citing motorists for seat belt non-use (primary enforcement)
have been shown to reduce motor vehicle crash deaths relative to secondary enforcement,
but the evidence base is dated and does not account for recent improvements in vehicle
designs and road safety. The purpose of this study was to test whether recent upgrades
to primary enforcement still reduce motor vehicle crash deaths.
Methods
In 2016, researchers used motor vehicle crash death data from the Fatal Analysis Reporting
System for 2000–2014 and calculated rates using both person- and exposure-based denominators.
Researchers used a difference-in-differences design to estimate the effect of primary
enforcement on death rates, and estimated negative binomial regression models, controlling
for age, substance use involvement, fixed state characteristics, secular trends, state
median household income, and other state-level traffic safety policies.
Results
Models adjusted only for crash characteristics and state-level covariates models showed
a protective effect of primary enforcement (rate ratio, 0.88, 95% CI=0.77, 0.98; rate
difference, –1.47 deaths per 100,000 population, 95% CI= –2.75, –0.19). After adjustment
for fixed state characteristics and secular trends, there was no evidence of an effect
of upgrading from secondary to primary enforcement in the whole population (rate ratio,
0.98, 95% CI=0.92, 1.04; rate difference, –0.22, 95% CI= –0.90, 0.46) or for any age
group.
Conclusions
Upgrading to primary enforcement no longer appears protective for motor vehicle crash
death rates.
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Article info
Publication history
Published online: March 20, 2017
Identification
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© 2017 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.
