Crash Outcome Data Evaluation System (CODES) Project Safety Belt and Helmet Analyses

Johnson, Sandy; Walker, Jonathan; Utter, Dennis · 1996 · ROSA P / United States. Department of Transportation. National Highway Traffic Safety Administration

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Summary

This study, conducted by the National Highway Traffic Safety Administration (NHTSA) under the Crash Outcome Data Evaluation System (CODES) project, evaluates the effectiveness of safety belts and motorcycle helmets in reducing injury severity and medical costs. The research was mandated by Section 1031(b) of the Intermodal Surface Transportation Efficiency Act of 1991 to provide Congress with data on the benefits of these safety devices. The study utilized data from seven states—Hawaii, Maine, Missouri, New York, Pennsylvania, Utah, and Wisconsin—where grants were awarded to link statewide crash and injury records. The methodology employed probabilistic linkage to connect police crash reports with emergency medical services, hospital emergency departments, discharge files, and insurance claims. This approach allowed researchers to track injured and uninjured individuals through the healthcare system, accessing both clinical outcomes and financial data. The study population included 879,670 passenger vehicle drivers for safety belt analyses and 10,353 motorcycle riders for helmet analyses. Effectiveness was defined as the percentage reduction in the likelihood of injury or death for users compared to non-users. Four outcome measures were used: death, death or inpatient admission, death/inpatient/EMS transport, and any injury. Regression analyses controlled for factors such as crash type, age, gender, and vehicle type for belt analyses, while helmet analyses primarily controlled for helmet use to prevent data exclusion. The results demonstrated that safety belts are highly effective in reducing morbidity and mortality, though estimates were adjusted for over-reporting of belt use in police records. Adjusted effectiveness estimates showed safety belts reduced the likelihood of death by 60%, death or inpatient admission by 45%, and any injury by 20%. Financially, unbelted drivers incurred average inpatient charges 55% higher than belted drivers ($13,937 vs. $9,004). For motorcycle helmets, effectiveness ranged from 9% in preventing any injury to 35% in preventing fatalities. Notably, helmets were 67% effective in preventing brain injuries. Unhelmeted riders faced an 8% increase in average inpatient charges ($15,578 vs. $14,377). The study highlighted that brain injuries incurred significantly higher costs, suggesting that universal helmet use would save approximately $15,000 in inpatient costs per rider by preventing these severe injuries. The significance of the CODES project lies in its demonstration that linked, comparable data can effectively evaluate the medical and financial benefits of safety equipment. The linkage process standardized injury severity metrics across states and created a permanent data file for future use. Furthermore, the project identified previously unknown issues with missing and inaccurate data in state records, leading to improvements in data quality. These findings provide robust evidence supporting the efficacy of safety belts and helmets, not only in saving lives but also in reducing the economic burden of crash-related injuries.

Key finding

Safety belts adjusted for over-reporting were 60 percent effective in preventing death and 20 percent effective in preventing any injury, while motorcycle helmets were 35 percent effective in preventing fatalities and 67 percent effective in preventing brain injuries.

Methodology

dataset

Sample size: 890023

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• helmet protective
• demographic disparities
• incidence prevalence
• adas effectiveness

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Empirical Findings: crash risk outcomes, observational prevalence