Estimates of Injury Impairment After Acute Traumatic Injury in Motorcycle Crashes Before and After Passage of a Mandatory Helmet Use Law,☆☆,,★★

General results presented at the Third World Congress on Injury Control, Melbourne, Australia, February 1996.
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Abstract

Study objective: This study estimates trends in impairment before and after the 1992 California Mandatory Helmet Use Law using the Injury Impairment Scale (IIS). Methods: We linked medical records and police reports for a cohort of 4,790 nonfatally injured motorcycle riders who crashed between January 1, 1991, and December 31, 1993, and were treated for injuries in 1 of 18 hospitals in 10 California counties. All injuries were coded according to the Abbreviated Injury Scale and matched to corresponding codes in the IIS. The IIS provides an estimate of the likelihood of impairment from any given injury. Impairment is not directly measured. Results: After implementation of the law, the proportion of riders likely to sustain head injury–related impairments decreased by 34.1%. Impairments resulting from head injuries were the most common type before passage of the law, but they were surpassed by leg injury–related impairments after passage. Helmet nonuse, speeding, and drinking were among variables associated with increased odds ratios of head injury estimated to cause impairment. Conclusion: The proportion of motorcycle riders with head injury impairment as estimated with the IIS decreased significantly after the introduction of mandatory motorcycle helmet legislation. [Peek-Asa C, Kraus JF: Estimates of injury impairment after acute traumatic injury in motorcycle crashes before and after passage of a mandatory helmet use law. Ann Emerg Med May 1997; 29:630-636.]

Section snippets

INTRODUCTION

Knowledge about the causes, diagnoses, treatment needs, and cost of care for acute traumatic injuries is increasing, but much less is known about long-term sequelae. The most commonly recognized long-term outcomes of acute traumatic injury are impairment and disability. Impairment is the loss or abnormality of mental, emotional, physiologic, or anatomic structure or function after healing. Disability refers to inability or limitation in carrying out socially defined tasks, activities or roles.1

MATERIALS AND METHODS

The 1992 California Mandatory Helmet Use Law Evaluation has been described elsewhere.22 For this report, the study group comprised 4,790 nonfatally injured motorcycle riders who crashed in California between January 1, 1991, and December 31, 1993. Riders treated in 1 of 18 hospitals in 10 California counties were included. All riders admitted to the 18 hospitals and riders treated and released from the EDs of 9 of the 18 hospitals were included. The participating hospitals were selected to

RESULTS

Before the introduction of the California Mandatory Helmet Use Law, 61.2% of all riders treated for nonfatal injuries were predicted to have some injury impairment on the basis of IIS score (Table 2). After implementation of the law, the portion of injured riders expected to have sustained any impairment decreased to 57.1% in 1992 and to 51.3% in 1993 (P <.001). The proportion of riders with head injury–related impairments decreased by more than 34%, from 32.3% before passage of the law to

DISCUSSION

The results of this study must be interpreted with caution because the IIS is based solely on the AIS score. We did not measure each individual's actual level of impairment. In only one published study has the estimate of the IIS on disability been validated, and this study revealed that as the IIS increases, longer periods of disability are found.25 However, the authors of this study also found that many subjects with IIS scores of 3 or greater had no disability or were disabled for very short

Acknowledgements

We are grateful to the individuals and agencies who contributed to this study, without whom this research could not have been completed: Walter Douglas Beck, Kathryn Brown, Elizabeth Daranciang, George Hsieh, Susan Iocolono, Janet Kraus, Linda Lange, Roberta McKean, Soumitra Sarkar, Heidi Smith, Michael Welch, Carol White, Carol Muldavid, Joyce Phillips, Jon Wong (UCLA); Gail Cooper (San Diego Emergency Medical Services Authority); John Bailey, Bev Christ, Michael Nivens (California Highway

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    From the Southern California Injury Prevention Research Center, University of California, Los Angeles, Los Angeles, CA.

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    Funded by the Insurance Institute for Highway Safety, the California Office of Traffic Safety, the Southern California Injury Prevention Research Center, and the UCLA Brain Injury Research Center. The opinions, findings, and conclusions expressed in this report are those of the authors and do not necessarily reflect the views of the supporting agencies.

    Reprint no.47/1/81342

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    Address for reprints: Corinne Peek-Asa, PhD Southern California Injury Prevention Research Center UCLA School of Public Health CHS 76-078 10833 Le Conte Avenue Los Angeles, CA 90095-1772

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