An estimated 9,500 deaths could be prevented annually in the United States if all motor vehicle occupants wore safety belts. Safety belt laws have been instrumental in increasing belt use, but whether primary laws (that allow police to stop motorists solely for being unbelted) are more effective than secondary laws has not been clearly established.
Using the methodology developed for the Guide to Community Preventive Services, we conducted a systematic review of the literature assessing effectiveness of primary versus secondary safety belt laws. We identified 14 studies, all of which met the quality criteria for inclusion in the review. Ten studies compared states with primary laws to those with secondary laws, and four studies evaluated the effect of changing from secondary to primary laws. Eight studies had concurrent comparison groups, four were before-after studies with multiple measurements, and two were cross-sectional studies.
Six studies reported fatalities as the outcome measure and eight reported safety belt use. The median decrease in fatalities was 5.4% greater (range: -16% to 15%) in primary law states than in secondary law states. The median increase in safety belt use in primary law states relative to secondary law states was 22.6% (range: 12.6% to 25.2%) for observed use. Two studies of self-reported use showed 0% and 49% increases. Eleven of fourteen studies showed greater benefits of primary versus secondary laws.
These results demonstrate that primary laws are more effective than secondary laws in increasing safety belt use and reducing fatalities.
Learning Objectives: 1. Describe the difference between primary and secondary laws. 2. Describe the steps used in a systematic review of evidence. 3. Discuss which safety belt use laws (primary or secondary) are more effective and why.
Keywords: Injury Prevention, Motor Vehicles
Presenting author's disclosure statement:
Organization/institution whose products or services will be discussed: None
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.