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• Injuries to Pedestrians and Bicyclists: An Analysis Based on Hospital Emergency Department Data

Injuries to Pedestrians and Bicyclists: An Analysis Based on Hospital Emergency Department Data

CHAPTER 5 - ALCOHOL USE BY INJURED PEDESTRIANS AND BICYCLISTS

The data collection form used to obtain information from injured pedestrians and bicyclists brought to hospital emergency departments contained a question on alcohol involvement. Although different procedures were followed by the hospitals with regard to testing or questioning for alcohol use, and in many instances alcohol use remained unknown, it was felt that an attempt should be made to gather whatever information was available since use of alcohol can be an important factor in pedestrian and bicyclist injury. As shown on the data collection form (appendix A), the response levels pertaining to the question on alcohol involvement were:

• Unknown/no information.
• Presumed not impaired.
• Not tested, but impairment indicated.
• Tested, and results of the testing (blood-alcohol level in mL/dL).

There was also a section on the data collection form pertaining to drug use. However, slightly more than 3 percent of the bicyclists (27 out of 814 with a response available for this variable) and none of the pedestrians brought to the emergency departments were suspected or tested positive for drug use. Thus, no comments pertinent to drug use will be offered for this small sample.

A variety of cross-tabulations were run to examine alcohol use separately for pedestrians and bicyclists. The text that follows covers pedestrian-motor vehicle, pedestrian-only, pedestrian-bicycle, bicycle-motor vehicle, bicycle-only, and bicycle-bicycle events. For these analyses, the "tested nd results" variable level has been dichotomized into two levels, "tested and drinking" and "tested, not drinking," based on the detection of any alcohol in the blood. Also, for some of the tables, the two categories, "tested and drinking" and "indicated as impaired," have been combined into a single category described as "had been drinking."

Table 31 shows the overall reported levels of alcohol involvement for the various event types. Highest levels of alcohol involvement were reported for the pedestrian-motor vehicle events: just over 13 percent of the cases were either indicated as impaired or were tested and found to have positive blood-alcohol levels. The corresponding percentage for bicyclists struck by motor vehicles was just over 10 percent. Percentages for "had been drinking" for the other injury event categories were generally in the 6-7 percent range (except for pedestrian-bicycle events, none of which involved alcohol). All of these percentages would be higher if calculated with the "unknowns" excluded from the table. However, the unknowns were left in the calculations, since the hospitals varied in whether they used "unknown" or "presumed not impaired" for young children who ordinarily would not be tested. In the remainder of the chapter, this situation is addressed by also examining tables excluding young children.

Table 31. Distribution of pedestrian and bicyclist injury event types by alcohol use.

¹ Percentage of row total. ² Percentage of column total.

Results for Injured Pedestrians

Pedestrian-Motor Vehicle Events

The emergency department database contained information on more than 500 pedestrians who had been struck by motor vehicles. As shown in table 31 above, alcohol use was either unknown or the pedestrians were presumed not impaired in 78 percent of the cases. Overall, 5 percent of the pedestrians were indicated as impaired, and another 8 percent were tested and found to have positive blood-alcohol levels. An additional 9 percent were tested and found not to be impaired.

Table 32, with information on the location of the injury event, shows that 64 of the 68 pedestrians (94 percent) who were either indicated as impaired or who tested positive for alcohol were struck while in the roadway. Of the seven pedestrians struck on sidewalks, two were impaired.

Table 32. Location where injury event occurred by alcohol use for pedestrian-motor vehicle events.

¹Percentage of row total. ² Percentage of column total.

Reported alcohol use was highest in the 25-44 age group (table 33). More than 15 percent of the injured pedestrians in this age group were indicated as impaired, and an additional 16 percent tested positive for alcohol. Stated differently, about 32 percent of this age group had been drinking. Just over 22 percent of the 45-64 age group had also been drinking (17.5 percent were tested and found to be impaired), but less than 8 percent of the 65+ age group had this result. Overall, about 24 percent of those age 20 and above had been drinking, compared to 14 percent for all age groups combined.

Nearly two-thirds of the pedestrians struck by motor vehicles were male (table 34). Some 16 percent of the males were found to have been drinking, compared to 9 percent of the females. For those age 20 and above, 26 percent of the males and 20 percent of the females had been drinking.

Table 33. Age by alcohol use for pedestrian-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

Table 34. Gender by alcohol use for pedestrian-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

In regard to race, just under half of the pedestrians were White, with 34 percent Black and 15 percent Hispanic (table 35). Nearly 15 percent of the White pedestrians had been drinking, compared to 10 percent for Blacks and 11 percent for Hispanics. For those age 20 and above, these values increased to 24, 18, and 23 percent, respectively.

Table 35. Race by alcohol use for pedestrian-motor vehicle events.

¹Percentage of row total. ² Percentage of column total.

Examining time of day, about 34 percent of the pedestrians were struck between 2-6 p.m. and another 29 percent between 6-10 p.m. (table 36). Alcohol impairment was more prevalent, however, in late evening and early morning hours. Some 20 percent of those struck between 6-10 p.m. had been drinking, compared to 45 percent for 10 p.m.-2 a.m. and 70 percent for 2-6 a.m. (7 of 10 cases). For age 20 and above, these values increased to 42, 50, and 86 percent (6 of 7 cases), respectively.

Fifty-seven percent of the pedestrians struck by motor vehicles were treated at the hospital emergency department and released, 38 percent were admitted to the hospital, and 3 percent were killed (table 37). The prevalence of alcohol use increased with increasing severity of the injury event: just over 9 percent of those treated and released had been drinking, compared to 18 percent of those admitted and 27 percent of those killed (4 out of 15 cases). For those age 20 and above, these values increased to 19, 28, and 40 percent, respectively. Four of the 15 fatally injured pedestrians had been drinking (1 indicated as impaired and 4 tested and drinking).

Table 36. Time of day by alcohol use for pedestrian-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

Table 37. Emergency department disposition by alcohol use for pedestrian-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

The tendency for drinking status to be associated with more serious injury is also supported by information on the specific locations and types of injuries sustained. The highest percentages of "had been drinking" were found among those pedestrians with injuries to the head, chest, and back or spine, and for those suffering intracranial or other internal injuries.

Pedestrian-Only Events

Information pertaining to more than 900 pedestrian-only events is also contained in the emergency department database. Persons injured in pedestrian-only events were generally less likely to have been drinking than those struck by motor vehicles. Overall, just under 6 percent of the pedestrians injured in pedestrian-only events were "indicated as impaired," while only a little over 1 percent were tested and found to have a positive blood-alcohol level (see table 31).

Table 38 presents information on alcohol use by the location of the injury event with respect to the roadway. Overall, only 22 percent of the pedestrian-only events occurred on the roadway, while 45 percent occurred on sidewalks and 20 percent in parking lots. Levels of alcohol use were generally highest for those injured on sidewalks, with 9 percent either indicated as impaired or tested and found to have been drinking. In contrast, 7 percent of those injured on the roadway were reported as drinking, and less than 4 percent of those injured in parking lots or driveways were reported as drinking.

Table 38. Location where injury event occurred by alcohol use for pedestrian-only events.

¹ Percentage of row total. ² Percentage of column total.

Unlike the motor vehicle events, the proportion of adults drinking varied only slightly among the various age groups (table 39). Just under 13 percent of the 20-24 age group had been drinking, compared to just over 13 percent of the 25-44 age group and 11-12 percent of the 45-64 age group. Among those age 65+, only 3 percent were reported to have been drinking. The vast majority of all of these were indicated as impaired rather than tested and drinking. Overall, more than 10 percent of those age 20 and above had been drinking, compared to 7 percent for all ages combined.

Table 39. Age by alcohol use for pedestrian-only events.

¹ Percentage of row total. ² Percentage of column total.

Although the majority of those injured in pedestrian-only events were female, males were more likely to have been drinking (table 40). More than 10 percent of the males had been drinking, compared to just 4 percent of the females. For those age 20 and above, 18 percent of the males and 5 percent of the females had been drinking.

Overall, 77 percent of this group of pedestrians were White, 14 percent Black, and 6 percent Hispanic (table 41). In general, Blacks and Hispanics were more likely to have been drinking than were Whites: 5 percent of the White group had been drinking, 10 percent of the Black (more than 9 percent indicated as impaired), and 11 percent of the Hispanic (half indicated as impaired and half tested and drinking). Above age 20, these values increased to 9, 17, and 23 percent, respectively.

Table 40. Gender by alcohol use for pedestrian-only events.

¹ Percentage of row total. ² Percentage of column total.

Table 41. Race by alcohol use for pedestrian-only events.

¹ Percentage of row total. ² Percentage of column total.

As was the case with pedestrian-motor vehicle events, although the vast majority of the pedestrian-only events occurred during the daytime, the nighttime events were much more likely to involve alcohol (table 42). One-fourth of those injured between 10 p.m. and 2 a.m. had been drinking (23 percent indicated as impaired) and 53 percent (8 out of 15 cases) of those injured between 2 a.m. and 6 a.m. had been drinking (all indicated as impaired).

Table 42. Time of day by alcohol use for pedestrian-only events.

¹ Percentage of row total. ² Percentage of column total.

Almost 92 percent of persons injured in pedestrian-only events were treated and released and 7 percent were admitted to the hospital (table 43). There were no fatalities. Six percent of those treated and released had been drinking, compared to 19 percent of those admitted. Pedestrians with injuries to the head were the most likely to have been drinking, but unlike the case with pedestrian-motor vehicle events, pedestrian-only events involving drinking were more likely to be associated with lacerations, dislocations, and other more superficial injuries.

Pedestrian-Bicycle Events

There were 21 collisions involving pedestrians and bicycles (table 31). In all of these cases, the pedestrian alcohol use was either unknown (5 cases) or presumed not impaired (16 cases).

Table 43. Emergency department disposition by alcohol use for pedestrian-only events.

¹ Percentage of row total. ² Percentage of column total.

Results for Injured Bicyclists

Bicycle-Motor Vehicle Events

A total of 320 cases in the hospital emergency department datafile involved bicyclists who had collided with motor vehicles (table 31). For these bicycle-motor vehicle events, 6 percent were indicated as impaired and 4 percent as testing positive for alcohol (i.e., tested and drinking). Ten percent were tested and found not to have been drinking, and alcohol use was either unknown or the bicyclist was presumed not to be impaired in the remaining 80 percent of the cases. The vast majority of bicycle-motor vehicle collisions occurred on the roadway, including all but one of those where the bicyclist had been drinking (table 44).

Bicyclists of all age groups were reasonably well represented in the data (table 45). Unlike the case with pedestrians, where alcohol involvement peaked with the 25-44 age group, the proportion of bicyclists drinking was reasonably constant for the 20-24, 25-44, and 45+ age groups (all around 14-15 percent). There was also more evidence of drinking by younger bicyclists: nearly 10 percent of the 15-19 age group were reported as drinking, compared to only 1 percent of the pedestrians in this age group. Overall, about 15 percent of those above age 20 had been drinking, compared to 10 percent for all age groups.

Four out of five bicyclists struck by motor vehicles were male (table 46). Some 11 percent of the males had been drinking, compared to 8 percent of the females. For those above age 20, 15 percent of the males and 14 percent of the females had been drinking. These gender differences are less than those found for pedestrians struck by motor vehicles.

Table 44. Location where injury event occurred by alcohol use for bicycle-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

Table 45. Age by alcohol use for bicycle-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

Table 46. Gender by alcohol use for bicycle-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

Overall, just over half of the bicyclists were White, with 28 percent Black and 15 percent Hispanic (table 47). More than 9 percent of the Whites had been drinking, compared to only 3 percent of the Blacks; however, 26 percent of the Hispanics had been drinking (half were indicated as impaired and half were tested and found to be drinking).

Table 47. Race by alcohol use for bicycle-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

Examining time of day, about 36 percent were struck between 2-6 p.m. and another 30 percent between 6-10 p.m. (table 48). Alcohol use was prevalent during these hours, but more so in late evening and early morning hours. About 11 percent of the bicyclists had been drinking during the 2-6 p.m. and 6-10 p.m. periods, but the percentage increased to 39 percent from 10 p.m.-2 a.m. For those above age 20, 21 percent had been drinking from 2-6 p.m. and 15 percent from 6-10 p.m.

Table 48. Time of day by alcohol use for bicycle-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

Seventy-two percent of the bicyclists struck by motor vehicles were treated and released, 22 percent were admitted to the hospital, and less than 2 percent were killed (table 49). About 8 percent of those treated and released had been drinking, compared to 15 percent of those admitted for further treatment. One of the five bicyclists killed had also been indicated as impaired.

Table 49. Emergency department disposition by alcohol use for bicycle-motor vehicle events.

¹ Percentage of row total. ² Percentage of column total.

Bicycle-Only Events

Some 746 bicyclists were treated in the participating hospital emergency departments as a result of injuries received from falls or other bicycle-only events not involving a motor vehicle. Of these, just under 6 percent had been drinking (table 31). In addition to roadways, sidewalks and trails were frequent locations for bicycle-only events (table 50). Of the bicyclists injured on the roadway, 9 percent had been drinking; however, only 3 percent of those injured on sidewalks had been drinking and none of those injured on trails had been drinking. Age is clearly a factor in these results, since young children are more likely to ride on sidewalks and trails than adults and are also less likely to be drinking.

Table 50. Location where injury event occurred by alcohol use for bicycle-only events.

¹Percentage of row total. ² Percentage of column total.

Information pertaining to bicyclist age is contained in table 51. Over half of the bicyclists were under the age of 15, and a third were under age 10. Alcohol was generally not a factor in the injuries to bicyclists under age 20. However, alcohol was involved in approximately 14-17 percent of the injury events to bicyclists in the 20-24, 25-44, and 45-64 age groups. Overall, nearly 15 percent of those age 20 and above had been drinking, compared to less than 6 percent for all age groups.

Table 51. Age by alcohol use for bicycle-only events.

¹ Percentage of row total. ² Percentage of column total.

Seventy percent of the bicyclists were male. Nearly 8 percent of the males had been drinking, compared to only 2 percent of the females (table 52). For those age 20 and above, 18 percent of the males had been drinking, and 5 percent of the females had been drinking.

Table 52. Gender by alcohol use for bicycle-only events.

¹Percentage of row total. ² Percentage of column total.

Overall, 71 percent of this group of bicyclists were White, 13 percent Black, and 11 percent Hispanic (table 53). Five to six percent of the Whites had been drinking, compared to 8 percent of Blacks and Hispanics. Above age 20, these values increased to 13, 23, and 24 percent, respectively.

Table 53. Race by alcohol use for bicycle-only events.

¹ Percentage of row total. ² Percentage of column total.

Examining time of day, although the greatest number of bicycle-only events occurred from 2-6 p.m., most of those involving alcohol occurred from 6-10 p.m., and the rate of alcohol involvement was highest late at night and during the early morning hours (table 54). Ten percent of the bicyclists injured from 6-10 p.m. had been drinking, increasing to nearly 23 percent of those injured from 10 p.m.-2 a.m. For age 20 and above, 47 percent of those injured between 10 p.m. and 2 a.m. had been drinking.

Table 54. Time of day by alcohol use for bicycle-only events.

¹ Percentage of row total. ² Percentage of column total.

Nearly 88 percent of the injured bicyclists were treated and released and 8 percent were admitted to the hospital (table 55). There was one fatality. Contrary to findings for other categories of injury events, those bicyclists who were admitted to the hospital as the result of a fall or other bicycle-only event were not more likely to have been drinking: about 6 percent of those treated and released had been drinking, compared to 3 percent of those admitted. Both percentages more than doubled for bicyclists age 20 and above.

Table 55. Emergency department disposition by alcohol use for bicycle-only events.

¹Percentage of row total. ² Percentage of column total.

Bicycle-Bicycle Events

There were 28 instances of one bicycle striking another. Two of the injured bicyclists (7 percent) had been drinking.

Summary of Results

Results for the pedestrian and bicyclist groups can be summarized as follows:

Pedestrian-Motor Vehicle Events

• The vast majority of pedestrians who had been drinking were struck on the roadway.
• Overall, 14 percent had been drinking.
• 32 percent of the 25-44 age group and 22 percent of the 45-64 age group had been drinking.
• Males were more likely to have been drinking than females.
• Alcohol use was more prevalent during the late evening and early morning hours.
• 9 percent of the pedestrians who were treated and released had been drinking, compared to 18 percent of those admitted to the hospital and 27 percent of those killed.

Pedestrian-Only Events

• About 60 percent of the pedestrians who had been drinking were injured on a sidewalk.
• Overall, 7 percent had been drinking.
• 13 percent of the 20-24 and 25-44 age groups had been drinking, and 11 percent of the 45-64 age group had been drinking.
• Males were more likely to have been drinking than females.
• 10 percent of Blacks and 11 percent of Hispanics had been drinking, compared to 6 percent of Whites.
• Alcohol use was more prevalent during the late evening and early morning hours.
• 6 percent of the pedestrians who were treated and released had been drinking, compared to 19 percent of those admitted to the hospital.

Bicycle-Motor Vehicle Events

• Virtually all of the bicyclists who had been drinking were struck on the roadway.
• Overall, 11 percent had been drinking.
• About 15 percent of the 20-24, 25-44, and 45-64 year groups had been drinking (10 percent of the 15-19 age group had been drinking).
• Overall, males were more likely than females to have been drinking, but above age 20, there was no difference in the male-female percentage.
• 9 percent of Whites, 3 percent of Blacks, and 26 percent of Hispanics had been drinking.
• Alcohol use was more prevalent during the late evening and early morning hours.
• 8 percent of the bicyclists who were treated and released had been drinking, compared to 15 percent of those admitted to the hospital.

Bicycle-Only Events

• Over 80 percent of bicyclists who had been drinking were injured on the roadway.
• Overall, 6 percent had been drinking.
• 14 to 17 percent of the 20-24, 25-44, and 45-64 age groups had been drinking, but only 5 percent of the 65+ age group had been drinking.
• Males were more likely than females to have been drinking.
• Five percent of Whites and 8 percent of Blacks and Hispanics had been drinking.
• Alcohol use was more prevalent during the late evening and early morning hours.
• Six percent of the injured bicyclists who were treated and released had been drinking, compared to 3 percent of those admitted to the hospital.

FHWA-RD-99-078