ALCOHOL AND/OR OTHER DRUG USE AMONG ADULT NON-OCCUPANT MOTOR VEHICLE CRASH VICTIMS

Jim Edward Weber1,2,*, Ronald F. Maio1,2, Frederic C. Blow3,4, Elizabeth M. Hill2, Kristen L. Barry4 and Patricia F. Waller5

1 Department of Emergency Medicine, University of Michigan Medical School,
2 University of Michigan Injury Research Center,
3 Department of Psychiatry, University of Michigan Medical School,
4 The Serious Mental Illness Treatment Research and Evaluation Center, Division of Veterans Affairs Health Services Research and Development and
5 University of Michigan Transportation Research Institute, MI, USA

Received 6 November 2001; accepted 19 March 2002


    ABSTRACT
 TOP
 FOOTNOTES
 ABSTRACT
 INTRODUCTION
 SUBJECTS AND METHODS
 RESULTS
 DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
Aims: To identify the frequency of current or lifetime history of alcohol and/or other drug (AOD) use among the full range (admitted and discharged) of injured bicyclists and pedestrians involved in motor vehicle crashes. Methods: In a prospective study of non-occupant motor vehicle crash (NOMVC) victims >=18 years over a 29-month period, blood was obtained for alcohol and drug testing. Current alcohol abuse/alcohol dependence (AA/AD) or drug abuse/drug dependence (DA/DD) was based on the Diagnostic Interview Survey. Results: In all, there were 108 NOMVC victims. Eleven per cent were alcohol (+), 7% drug (+), and 3% both. Sixteen per cent were AA/AD (+), 2.7% DA/DD (+), and 1.4% both. Conclusions: A substantial portion of patients with NOMVC injuries tested AOD (+) and had a current or lifetime substance abuse (AA/AD; DA/DD) diagnosis.


    INTRODUCTION
 TOP
 FOOTNOTES
 ABSTRACT
 INTRODUCTION
 SUBJECTS AND METHODS
 RESULTS
 DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
Although much attention has been given to motor vehicle occupant safety during the past decade, the related issue of bicycle and pedestrian (non-occupant) safety has not been well examined. Bicycling is the leading cause of recreational injury in the USA, resulting in almost 600 000 emergency department (ED) visits and 900 deaths annually (Baker et al., 1993Go). Correspondingly, >80 000 pedestrian injuries and ~8000 deaths occur annually (National Center for Health Statistics, 1993Go). Numerous demographic and environmental factors have been linked to non-occupant motor vehicle crash (NOMVC)-related injury (Stevenson et al., 1995Go; Roberts et al., 1995Go; Rivara et al., 1997Go). Although the use of alcohol and/or other drugs (AOD) and their effects on injury and crash characteristics have previously been reported for motor vehicle occupants (Waller et al., 1997Go), data regarding the prevalence of alcohol and drug use among non-occupant injury victims is scarce, and is largely limited to admitted trauma centre patients and fatalities (Jehle and Cottington, 1988Go; Brainard et al., 1989Go; Vestrup and Reid, 1989Go; Li and Baker, 1994Go; Lane et al., 1994Go; Holubowycz, 1995Go; Rogers, 1995Go; Li et al., 1996Go). Consequently, failure to identify injured patients who use alcohol and illicit drugs who present to the ED may adversely impact the care they receive, and additionally lead to missed opportunities to identify at-risk patients as a target group for prevention and/or early intervention strategies. Therefore, the specific aims of this study were to identify the frequency of alcohol and drug use as well as the current or lifetime history of alcohol abuse/alcohol dependence (AA/AD) and drug abuse/drug dependence (DA/DD) among the full range of injured NOMVC victims who present to the ED.


    SUBJECTS AND METHODS
 TOP
 FOOTNOTES
 ABSTRACT
 INTRODUCTION
 SUBJECTS AND METHODS
 RESULTS
 DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
General procedures
This is a secondary analysis of prospective data collected to determine the effects of AOD on motor vehicle-related occupant injury. Patients were considered for enrolment if they were aged >=18 years, victims of a bicycle or pedestrian motor vehicle-related injury, and presented directly from the crash scene to the ED within 6 h of the crash. Patients were excluded from this study if they were transferred from another hospital, aged <18 years, pregnant, or institutionalized in either a prison or a mental institution. Patients were recruited from two EDs; one a large university hospital verified as a Level I Trauma Center, and the other, a large university-affiliated community teaching hospital. Data collection occurred over a 29-month period in the University hospital and a 15-month period in the community hospital. The total time period for the study was April 1992 to August 1994. Because of the variability of ED volume of MVC cases across the time of day and the day of week, project personnel were selectively deployed across shifts. At the community hospital site, a convenience sample was studied by sampling evening shifts. At the University hospital, the subjects were sampled using full sampling during the evening shifts (15:30–23:30). Time sampling was implemented during the day and midnight shifts, and consisted of 2-week blocks in which day and night shifts were covered on 3 consecutive days; days the first week in the block, nights the second week in the block. The start day of these blocks was shifted sequentially throughout the study period, so that all days of the week were sampled during each month of the year. By differentially weighting cases from the three shifts, a representative sample of ED patients at the University site can be estimated. Maio et al. (1997) described the characteristics of these samples in detail elsewhere.

A more detailed description of the methods utilized in this study has been previously reported by Waller et al. (1997). In brief, injured patients were approached by ED physicians or trained research assistants for enrolment into the study. If study criteria were met, the study was explained by the project interviewer, and consent was obtained. Blood for study purposes was provided only after obtaining informed consent. If the patient’s injury severity prohibited obtaining informed consent, blood was drawn and stored until the patient was sufficiently recovered, and consent was obtained. Consent was requested from a family member of those subjects who died or were too disabled to participate in the study. In these cases, guardian interviews substituted for the subject interviews. No analyses were obtained without consent. This study was approved by the Institutional Review Boards of both institutions.

Three types of data were included for analysis: (1) demographic information, obtained from both patients and hospital records; (2) alcohol and drug data, obtained from laboratory analyses of blood samples; (3) information on previous alcohol and drug use, obtained from a structured interview [Diagnostic Interview Survey (DIS; DSM III-R), Robins et al., 1989].

Demographic data
Demographic information included basic information on age, race, marital status, education, number of children, and occupation.

Alcohol and drug data
All laboratory analyses were performed by Labcorps Inc., Research Triangle Park, NC, USA. Alcohol testing was conducted by whole blood analysis using gas chromatography or breath analysis. Drug testing was also performed on whole blood. Using radioimmunoassay, initial screening was performed for cocaine metabolites (benzoylecgonine), cannabanoid metabolites [THCA (11-nor-delta-8-tetrahydrocannabinol-9-carboxylic acid)], opiates (morphine); cut-offs were 50, 10 and 50 ng/ml respectively. Samples testing positive for radioimmunoassay were then analysed using gas chromatography and mass spectroscopy (GC/MS analysis) for quantitative results.

Alcohol and drug history
A diagnosis of AA/AD or DA/DD was determined using the alcohol and drug section of the DIS (Robins et al., 1989Go). The DIS is a validated standardized diagnostic instrument based on DSM III-R criteria, and contains 30 stem questions administered in a standardized format. Diagnosis was considered current if any symptoms had occurred during the past year. The DIS also identifies the number of lifetime symptoms related to alcohol and drug use.

Statistical analysis
Data were analysed using the SAS 6.12 (Cary, NC, USA) database for analysis. Due to limited sample size, substance-positive groups were pooled for analysis, as were data regarding pedestrians and bicyclists. Bivariate analyses were performed using {chi}2-tests and Wilcoxon rank sum scores, where appropriate, for variable distributions. P < 0.05 was considered statistically significant, and P < 0.1 was considered a statistical trend. No correction for multiple comparisons was made, because the tests were a priori hypotheses, based on previous research.


    RESULTS
 TOP
 FOOTNOTES
 ABSTRACT
 INTRODUCTION
 SUBJECTS AND METHODS
 RESULTS
 DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
There were 108 NOMVC patients who presented during shifts that were designated during time sampling. Of these, 92 patients had a hospital alcohol level or a breathalyser performed and were approached for participation. Sixteen patients were excluded because they were either missed or ineligible. We analysed for possible selection bias for the entire sample, by comparing characteristics between patients who were approached for recruitment and those who were ineligible or missed. No significant differences were noted for age, gender, ethnicity, or fault of accident. Of the 92 patients enrolled, 17 refused to consent to a personal interview. The specific reasons for refusal are listed as follows: Not interested in the project (n = 7), advised not to participate by a family member, friend, or lawyer (n = 1), language barrier (n = 2), objected to alcohol assessment as a whole (n = 2), other (n = 5). Interestingly, no patient refused due to concerns of confidentiality. Those who consented to an interview (n = 75) were compared to those who refused (n = 17). The only significant difference was that victims who were drinking [BAC+ (blood alcohol concentration)] were less likely to consent to an interview [57.1% BAC (+) vs 85.9% BAC (–); P < 0.02].

Eleven per cent of NOMVC victims tested positive for alcohol alone, 7% for drugs alone, and 3% for both. Table 1Go shows a comparison of demographics, as well as current or lifetime substance abuse diagnosis. Victims with a current substance abuse diagnosis were more likely to have tested positive for alcohol or drugs (AA/AD, P = 0.003; DA/DD, P = 0.028). Sixty-one (66%) subjects were treated and released from the ED.


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Table 1. Characteristics of non-occupant motor vehicle accident victims, according to presence of alcohol or other drugs (AOD)
 

    DISCUSSION
 TOP
 FOOTNOTES
 ABSTRACT
 INTRODUCTION
 SUBJECTS AND METHODS
 RESULTS
 DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
The results of our study have yielded two important findings. First, >20% of NOMVC victims tested positive for alcohol, other drugs, or both. Although several studies have defined intoxication as a risk factor for non-occupant crashes (Haddon et al., 1961Go; Struik and Rogerson, 1988Go; Honkanen and Smith, 1990Go), none has adequately addressed the overall frequency of alcohol or drug use among both admitted and discharged NOMVC victims. The frequency of alcohol use among injured pedestrians has been reported as 30–48% (Cimbura et al., 1982Go; Irwin et al., 1986Go; Richter et al., 1986Go; Vestrup and Reid, 1989Go). Similarly, the frequency of alcohol use among injured bicyclists admitted to trauma centres has been reported as high as 16% (Frank et al., 1995Go; Yelon et al., 1995Go; Li et al., 1996Go). Only one previous study examined injury severity among all injured bicyclists who presented to the ED (Spaite et al., 1995Go), and found the frequency of alcohol use among injured victims similar to ours (8 vs 11%). Seven per cent of NOMVC victims in our study tested positive for drugs, similar to previous estimates among the US population in general (Substance Abuse and Mental Health Services Administration, 1996Go). Existing data on drug use in trauma victims were previously limited to motor vehicle crash victims (Honkanen et al., 1980Go; Waller et al., 1986Go), and fatally injured or admitted trauma centre patients (Rivara et al., 1989Go).

Second, 16% of injured bicyclists and/or pedestrians had either a lifetime or current diagnosis of AA/AD, more than twice that of previously reported estimates of the prevalence of current AA/AD in the general US population (Kessler et al., 1994Go). These findings support the importance of screening and intervention for AA/AD among NOMVC victims.

The following study limitations are noteworthy: (1) Our data are largely descriptive due to the small number of victims meeting enrolment criteria. (2) Because only the evening shift was covered throughout the entire study, with sampling of other shifts at the community hospital, the study population cannot be considered to be characteristic of all bicycle and pedestrian crashes presenting to the participating hospitals. However, the sample is valid for determining how descriptive characteristics differ among those testing positive for AOD versus those who tested negative. (3) Because of the small sample size, we were unable to make valid comparisons of injury severity among AOD (+) and AOD (-) patients. Studies involving alcohol and motor vehicle crashes, and those on bicycle and pedestrian injuries, have not adequately addressed variations of injury severity based on impact forces. Recently, a population-based study that considered the force of impact among injured pedestrians reported a 4–5-fold increase in the odds of dying when alcohol was present (Miles-Doan, 1996Go). However, no clinical study involving injured non-occupants has adequately controlled for forces of impact. (4) We cannot exclude the possibility of bias when considering the analyses of drinking history information, since victims who were BAC (+) were less likely to consent to an interview. In addition, the sample of victims who consented to be interviewed and to provide blood samples for analysis may underestimate the frequency of past history of dependence and of substance abuse other than alcohol.

In conclusion, a considerable number of NOMVC victims who presented to the ED tested AOD (+). When compared to AOD (-) NOMVC victims, those testing AOD (+) were significantly more likely to have a current or lifetime substance abuse diagnosis and a greater severity of injury. This information is useful for the development of injury prevention strategies to decrease the incidence and severity of adult NOMVC injuries.


    ACKNOWLEDGEMENTS
 TOP
 FOOTNOTES
 ABSTRACT
 INTRODUCTION
 SUBJECTS AND METHODS
 RESULTS
 DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
This study was funded by the National Institutes of Health/National Institute for Alcohol Abuse and Alcoholism, RO1 AA09110-01 and was presented at the 43rd meeting of the Association for the Advancement of Automotive Medicine, Barcelona, Spain, September, 1999.


    FOOTNOTES
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 FOOTNOTES
 ABSTRACT
 INTRODUCTION
 SUBJECTS AND METHODS
 RESULTS
 DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
* Author to whom correspondence should be addressed at: Department of Emergency Medicine, Hurley Medical Center, One Hurley Plaza, Flint, MI 48503-5993, USA. Back


    REFERENCES
 TOP
 FOOTNOTES
 ABSTRACT
 INTRODUCTION
 SUBJECTS AND METHODS
 RESULTS
 DISCUSSION
 ACKNOWLEDGEMENTS
 REFERENCES
 
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