Current Trends Safety-Restraint Assessment -- Iowa, 1987-88

From November 1987 to March 1988, the Iowa Safety Restraint Assessment (ISRA)* study gathered data on injuries to and hospital charges for persons who survived motor vehicle crashes and presented for emergency medical care at one of 16 hospitals in Iowa. The participating hospitals (seven rural and nine urban) represented all levels of trauma care and all geographic quadrants of the state (Figure 1).

The 1454 persons injured in motor vehicle crashes who were studied during the 5-month period represented approximately 20% of all persons who were injured and who presented for emergency medical care in Iowa during the same period. Safety- restraint status was determined through questions to the patient or ambulance personnel. Of the 1454 injured persons, 697 (48%) were wearing safety restraints at the time of the crash (belted), and 757 (52%) were not (unbelted). Unbelted persons were more likely than belted persons to be male, be younger, have higher reported alcohol use at the time of the crash, and report motor vehicle crash speeds greater than or equal to 55 mph (Table 1).

Twenty-seven percent of unbelted persons were admitted to a hospital (Table 2). Unbelted persons were three times more likely than belted persons to be hospitalized, 8.4 times more likely to sustain a head injury with loss of consciousness, 2.7 times more likely to sustain a fracture, and 2.8 times more likely to sustain a laceration. Strains or sprains were reported more frequently among belted than among unbelted persons.

The average hospital bill was significantly higher for unbelted ($2462) than for belted persons ($753) (p less than 0.01). The average hospital stay was 2.6 times longer for unbelted (16.9 days) than for belted persons (6.6 days).

Most injuries were minor and external (e.g., abrasions, contusions, and lacerations)--391 (51.7%) among unbelted and 296 (42.5%) among belted persons. Based on the Abbreviated Injury Scale (AIS)--for which severity scores range from 1 (minor) to 6 (most critical) for each anatomic region (1)--injuries were more severe in all anatomic regions for unbelted than for belted persons. These differences were statistically significant (p less than 0.01) for all areas except the face and the abdomen and pelvis. For head injuries, the average AIS score was 1.6 for belted persons and 2.6 for unbelted persons; for injuries to the thorax, the average score was 1.8 for belted persons and 2.3 for unbelted persons. Overall, the average AIS score was 1.2 for belted and 1.5 for unbelted persons.

At both low- and high-impact speeds, unbelted occupants were more likely to incur head injuries, fractures, and lacerations. At low-impact speeds (less than or equal to 30 mph), 1.1% of belted persons received head injuries; 3.7%, fractures; and 8.8%, lacerations. For unbelted persons, 7.8% incurred head injuries; 9.5%, fractures; and 26.6%, lacerations. At high-impact speeds (greater than 30 mph), 2.5% of belted persons received head injuries; 11.9%, fractures; and 16.3%, lacerations. For unbelted persons, 20.3% received head injuries; 29.8%, fractures; and 41.3%, lacerations. Reported by: TD Peterson, MD, KM Royer, Iowa Methodist Medical Center, Des Moines, Iowa. Biometrics Br, Div of Injury Epidemiology and Control, Center for Environmental Health and Injury Control, CDC.

Editorial Note

Editorial Note: This statewide hospital evaluation of motor vehicle crash morbidity, which is modeled after a 1986 pilot study in Keokuk, Iowa (2), serves as a model for future injury surveillance.

Since July 1986, Iowa has had a primary enforcement safety-restraint law. Observational studies conducted by the Iowa Department of Transportation found that safety-restraint compliance was56% in September 1987 and 55% in September 1988 (3,4). In the ISRA, 48% of injured persons were belted, which may suggest that belted persons have fewer motor vehicle crashes and/or are less likely to have injuries requiring emergency care.

Most injuries reported were minor, especially for belted persons. Minor injuries can be a source of temporary disability and medical expense but are seldom reported in case studies. Soft-tissue injuries, such as strains and sprains, may be underreported among unbelted persons because seriously injured patients are less likely (or unable) to complain about soft-tissue injury, and trauma teams are less likely to address these injuries when life-threatening injuries are present.

The ISRA demonstrated that among persons who were injured and used safety restraints injuries were less severe and cost less. Reduction of motor vehicle crash injury and subsequent effects will require increased public awareness of the benefits of correct and consistent safety-restraint use. Methods to reach this goal include:

• Emphasis on the ability of safety restraints to reduce crash injuries and associated hospital costs, disability, and death.

• Instruction of children about the importance of wearing safety restraints to reduce the risk of severe injury in a crash so that safety-restraint use becomes routine before adolescence and early adulthood.

• Education of persons 16-24 years of age--who are at greatest risk for traffic-related injury--about preventive behavior (safety-restraint use and alcohol avoidance) and traffic safety enforcement (compliance with speed limit and alcohol consumption laws).

Since 1975, detailed mortality data have been collected on all motor vehicle crash deaths by the National Highway Traffic Safety Administration using the Fatal Accident Reporting System. Data are limited on nonfatal motor vehicle crash injuries, such as those reported in the ISRA. A comprehensive database on injuries and disabilities will require integrated morbidity and mortality data collection at the local, state, and federal levels (5). In addition, such data linkage will require collaboration between public service agencies, the medical community (e.g., physicians, nurses, coroners, hospital staff, and prehospital emergency medical-care staff), police, highway and transportation departments, and others.

References

1. Committee on Injury Scaling, American Association for Automotive Medicine. Abbreviated injury scale, 1985 revision. Arlington Heights, Illinois: American Association for Automotive Medicine, 1985.

2. Peterson TD. Trauma prevention from the use of seat belts. Iowa Med 1987;(May):233-6.

3. Office of Driver Services, Iowa Department of Transportation. Observational Safety Belt Usage Survey. Des Moines, Iowa: Iowa Department of Transportation, 1987.

4. Office of Driver Services, Iowa Department of Transportation. Observational Safety Belt Usage Survey. Des Moines, Iowa: Iowa Department of Transportation, 1988.

5. Committee on Trauma Research, Commission of Life Sciences, National Research Council and the Institute of Medicine. Injury in America. Washington, DC: National Academy Press, 1985.

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