Effect of Mandatory Bicycle Helmet Legislation on Helmet Use and Injury Outcomes: A Propensity Score-Matched Analysis...

Area of Science:

• Public Health
• Epidemiology
• Trauma Research

Background:

• A non-penal bicycle helmet mandate was enacted in South Korea on September 28, 2018.
• Limited epidemiologic data exists on the mandate's impact on helmet usage and injury outcomes.
• This study aims to assess the mandate's effect on helmet-wearing behaviors and injury patterns.

Purpose of the Study:

• To evaluate changes in bicycle helmet use and injury outcomes before and after the mandate.
• To identify demographic and regional factors associated with helmet non-use.
• To analyze trends in helmet usage and injury severity using interrupted time-series analysis.

Main Methods:

• Retrospective observational study using the Korea Trauma Data Bank (2017-2022).
• Propensity score matching (1:1 caliper 0.10) for 4798 bicycle-injured patients.
• Analysis of helmet use, physiological status, Injury Severity Score (ISS), Abbreviated Injury Scale (AIS), and mortality.
• Segmented logistic regression and regression tree analysis for time-series trends.
• Multivariable logistic regression to identify factors associated with helmet non-use.

Main Results:

• Helmet use increased modestly from 17.4% to 21.9% post-mandate (p < 0.001).
• No immediate change in helmet use trends observed at mandate implementation or identified breakpoint.
• Injury Severity Score (ISS) > 15 increased post-mandate (21.5% to 24.4%, p = 0.02).
• Total mortality rose from 3.9% to 5.3% (p = 0.02).
• Helmet non-use associated with older age (80-89), female sex, non-Korean nationality, and Jeollabuk-do residence.

Conclusions:

• The mandate led to a gradual, modest increase in helmet wearing but no significant behavioral shift.
• Legislation alone, without enforcement, may have limited effectiveness.
• Complementary strategies like targeted education and region-specific safety measures are recommended.