Structured Abstract
Brain Injury Structured Abstract - BI #7
Helmets are effective in reducing head injury across age groups, type of accident, and type and certification of helmet
CITATION: Thompson, D. C., Rivara, F. P., & Thompson, R. S. (1996). Effectiveness of bicycle safety helmets in preventing head injuries: A case-control study. JAMA, 276(24), 1968-1973.
LEVEL OF EVIDENCE: IIA1a
This case prospective control design study, sample size ranged 3,390, with high internal validity and high external validity provided a IIA level of evidence.
RESEARCH OBJECTIVE/QUESTION
To examine protective effects of bicycle helmets in 4 age groups in motor vehicle accidents by type and certification standards.
DESIGN
| |
RCT |
|
Single Case |
X |
Case Control |
| |
Cohort |
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Before-After |
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Cross-Sectional |
This study is also known as a retrospective study or a case comparison study. A case control study is generally performed to view in retrospect to see how a certain issue affected a group of clients involved in the study. Therefore, one can find out what makes these clients different from each other. The group of clients exposed to the issue in question is compared to a similar control group that was not exposed to the issue.
SAMPLING PROCEDURE
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Random |
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Consecutive |
|
X |
Controlled |
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Convenience |
Individuals for the study are selected according to criteria that have been pre-selected for that certain study. This sampling procedure is not necessarily composed of volunteers but people who fit the criteria. In this study, the participants came from a pool of any individual involved in a bike accident in the major hospitals in the study. Control subjects for the study were bicyclists with injuries to other parts of the body.
SAMPLE
|
N = 3,390 |
M age =
< 6 - > 40 |
Male = 2,438 |
Ethnicity = NR |
Female = 952 |
NR = Not reported
Participants in the study totaled 3,390 injured bicyclists which 29% of cases and 56% of controls were helmeted. Cases and controls differed by age, sex, education, and income.
PARTICIPANT CHARACTERISTICS
Head Injured
MEDICAL DIAGNOSIS/CLINICAL DISORDER
Traumatic Brain Injury
OT TREATMENT DIAGNOSIS
Environmental (sociocultural) problems
Prevention
OUTCOMES
1. Tri-LODE Software Program
2. Study's Questionnaire
3. Injury Severity Scale
4. Glasgow Coma Scores
|
Measures |
Reliability |
Validity |
|
1. Tri-Code injury and severity coding |
NR |
NR |
|
2. Detailed questionnaires
- Crash Circumstances
- Demographic Data
- Crash Severity
- Self-Record
- Self-Report Speed
- Riding Experience
- Helmet
- Type
- Certification
- Size
- Brand
- Mold
|
NR |
NR |
|
3. The Injury Severity Scale Scores |
NR |
NR |
|
4. Glasgow Coma Scores |
NR |
NR |
NR = Not Reported
Outcome - OT terminology
III Performance Content
B-Environmental Aspects
2. Social
3. Cultural
Outcome - ICIDH-2 terminology
Participation - Environmental and cultural aspects - prevention
INTERVENTION
1. Prevention head injury
2. Prevention non-head injury
Description
1. Helmet type
Hard shell
Thin shell
No shell
2. Helmet certification standards
Snell - United States - Snell Memorial Foundation (most rigorous)
ANSI - American National Standards Institute
SSTM - American Society for Testing and Material
Who delivered
- Trained abstractors
- Emergency room doctors
Setting
7 Hospitals in Seattle, WA, Area:
- Central and Eastside Hospital, Puget Sound
- U of Washington Medical Center
- Harborview Medical Center
- Overlake Medical Center
- Children's Hospital and Medical Center of Seattle
- Mary Bridge Hospital of Tacoma
- Medical Examiners Offices-Pierce & King Counties
Frequency
1 time - 2 times week
Duration
March 1, 1992-August 31, 1994 (2½ years)
RESULTS
There were 3,390 injured bicyclists in the study; 29% of cases and 56% of controls were helmeted. Risk of head injury in helmeted vs. un-helmeted cyclists adjusted for age and motor vehicle involvement indicate a protective effect of 69% to 74% for helmets for 3 different categories of head injury: (odds ratio [OR], 0.31; 95% confidence interval [CI], 0.26 = 0.37), brain injury (OR, 0.35; 95% CI, 0.24 - 0.48), or severe brain injury (OR, 0.26; 95% CI, 0.13-0.48). Adjusted ORs for each of 4 age groups (6y, 6-12y, 13-19y, and > or = to 20 years) indicate similar levels of helmet protection by age (OR range, 0.27-0.40). Helmets were equally effective in crashes involving motor vehicles (OR, 0.31; 95% CI, 0.20-0.48) and those not involving motor vehicles (OR, 0.32; 95% CI, 0.20-0.39). There was no effect modification by age or motor vehicle involvement (P = .7 and P = .3). No significant differences were found for the protective effect of hard-shell, thin-shell, or no-shell helmets
CONCLUSIONS
Biases
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Attention |
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Masking/blinding |
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Drop outs |
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Contamination |
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Co-intervention |
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Bicycle helmets, regardless of type, provide substantial protection against head injuries for cyclists of all ages involved in crashes and motor vehicle accidents
Terminology used in this document is based on two systems of classification current at the time the evidence-based literature reviews were completed: Uniform Terminology for Occupational Therapy Practice - Third Edition (AOTA, 1994) and International Classification of Functioning, Disability and Health (ICIDH-2) (World Health Organization [WHO], 1999). More recently, the Uniform Terminology document was replaced by Occupational Therapy Practice Framework: Domain and Process (AOTA, 2002), and modifications to ICIDH-2 were finalized in the International Classification of Functioning, Disability and Health (WHO, 2001).
This work is based on the evidence-based literature review completed by Beatriz C. Abreu, PhD, OTR, FAOTA, and colleagues. For more information about the Evidence-Based Literature Review Project, contact the Practice Department at the American Occupational Therapy Association, 301-652-6611, x 2040.
Copyright 2003 American Occupational Therapy Association, Inc. All rights reserved. This material may be reproduced and distributed without prior written consent.
