Trends in Motorcycle Fatalities Associated With Alcohol-Impaired Driving—United States, 1983-2003

MMWR. 2004;53:1103-1106

1 figure, 1 table omitted

Motorcycles are the most dangerous type of motor vehicle to drive.¹ These vehicles are involved in fatal crashes at a rate of 35.0 per 100 million miles of travel, compared with a rate of 1.7 per 100 million miles of travel for passenger cars. The National Highway Traffic Safety Administration (NHTSA) has reported increasing numbers of motorcycle deaths associated with alcohol-impaired driving in recent years, especially among persons aged ≥40 years.² To determine trends by age group in motorcycle fatalities overall and in those involving alcohol impairment, CDC analyzed data from the NHTSA Fatality Analysis Reporting System (FARS) for 1983, 1993, and 2003. This report summarizes the results of that analysis, which indicated that, during 1983-2003, the overall prevalence of elevated blood alcohol concentrations (BACs) among motorcycle drivers who died in crashes declined; however, the peak rate of death among alcohol-impaired motorcycle drivers shifted from those aged 20-24 years to those aged 40-44 years. Strong enforcement of existing BAC laws, together with other public health interventions aimed at motorcyclists, might reduce the crash mortality rate, especially among older drivers.

FARS is an active, population-based surveillance system for motor-vehicle crashes that occur on public roadways in the United States and result in the death of an occupant or nonoccupant (e.g., pedestrian) within 30 days of the crash. FARS data are extracted primarily from law enforcement accident reports, which typically document driver BACs. However, for the approximately 35% of fatally injured drivers for whom BACs are unknown, NHTSA imputes BACs from driver and crash characteristics.³ For this analysis, a BAC level ≥0.08 g/dL, the legal limit in all states, was defined as alcohol impairment. This analysis was restricted to persons who died as a result of injuries sustained while driving a motorcycle or passenger car. The passenger car category does not include pickups, vans, or sport-utility vehicles. Rates were calculated by using U.S. census population estimates for 1983, 1993, and 2003.⁴

Overall, motorcycle mortality rates per 100,000 population declined from 1.6 in 1983 to 0.9 in 1993 and then increased to 1.2 in 2003. Most of the decline occurred among motorcyclists aged <30 years. For example, among drivers aged 20-24 years, the mortality rate declined from 5.0 in 1983 to 3.0 in 1993 and 2.4 in 2003, whereas among drivers aged 40-44 years, the mortality rate declined from 1.2 in 1983 to 1.0 in 1993 and then increased to 1.9 in 2003 (Figure). Among alcohol-impaired motorcycle drivers, the mortality rate was highest among persons aged 20-24 years in 1983 and among persons aged 40-44 years in 2003. In 1983, 8.2% of alcohol-impaired, fatally injured motorcycle drivers were aged ≥40 years; by 2003, 48.2% of such drivers were in this age group.

During 1983-2003, the overall proportion of both motorcycle and passenger-car drivers dying in crashes who were alcohol impaired declined (Table). Alcohol impairment occurred less often in automobile drivers of all ages in 2003 compared with 1983. This decrease also was observed among motorcycle drivers, except for persons aged 55-59 years, for whom the proportion with alcohol impairment increased from 16.7% in 1983 to 21.1% in 2003. In 2003, the proportion of fatally injured drivers with alcohol impairment was consistently lower among motorcycle drivers than among passenger-car drivers at each age through age 34 years. After age 34 years, however, higher proportions of motorcycle drivers than passenger-car drivers were alcohol-impaired.

Reported by: LJ Paulozzi, MD, R Patel, MPH, Div of Unintentional Injury Prevention, National Center for Injury Prevention and Control, CDC.

CDC Editorial Note: Sales of new on-road motorcycles increased substantially from 1997 through 2003, from 247,000 to 648,000 units.⁵ This increase coincided with a 69.8% increase in the number of motorcyclist traffic fatalities during that period, from 2,116 in 1997 to 3,592 in 2003.⁶ The increased number of motorcycles on the road probably contributed to the increase in the motorcycle mortality rate during 1993-2003. The mortality rate increase has been restricted to older motorcycle drivers.

Although the proportion of alcohol-impaired motorcycle drivers in fatal crashes declined from 48.6% in 1983 to 29.5% in 2003, the decline has been comparatively small among motorcycle drivers aged ≥40 years. Mortality rates might be increasing among motorcycle drivers aged ≥40 years, not only because more persons in this age group are riding motorcycles, but also because older motorcycle drivers might now be more likely to consume alcohol before driving than younger motorcycle drivers. Older drivers might be more likely than younger drivers to limit their riding to recreational trips on weekends under circumstances that might involve alcohol consumption.

The findings in this report are subject to at least three limitations. First, because BAC levels were imputed forsome cases, they must be considered estimates. Second, drinking drivers might be overrepresented among motorcycle drivers compared with passenger-car drivers because of other risk factors associated with drinking among motorcyclists. For example, motorcyclists who drink are also less likely to wear helmets,² a factor that increases the risk for death in a motorcycle crash.⁷ Finally, because the number of motorcycle drivers in each age group is not known, age-specific rates cannot be calculated on the basis of the number of drivers in each age group nor on more sensitive measures (e.g., the number of miles of motorcycle travel by each age group).

Efforts to reduce alcohol consumption among motorcyclists should target older drivers. Several measures are effective in reducing the rate of alcohol-impaired driving.⁸ Certain measures, including sobriety checkpoints, enhanced enforcement of 0.08 g/dL BAC laws, and some types of server-intervention programs to reduce alcohol consumption in bars and restaurants, are most likely to impact motorcycle drivers aged ≥40 years. Laws setting a BAC limit of 0.08 g/dL for drivers have already been passed in all 50 states. Strong enforcement of these laws, together with other public health interventions aimed at motorcyclists, might help reduce the crash mortality rate, especially among older drivers. Because BAC levels less than the legal limit also adversely affect performance,⁹ drivers of all ages can help by avoiding the consumption of any alcohol before driving.

This report is based, in part, on contributions by T Lindsey, National Highway Traffic Safety Admin, Washington, DC.