Morris Odell

Drug use in motor vehicle drivers presenting to an Australian, adult major trauma centre

Objectives:  To determine the drug use in injured Victorian drivers involved in motor vehicle collisions and subsequently transported to a major adult trauma centre in Victoria.

Implications of Vision Testing for Older Driver Licensing

Objectives. A range of medical conditions can lead to visual impairments either through effects on the eye or the visual pathways and brain. The prevalence of visual impairment increases with age. Furthermore, research evidence has shown that aging is related to a number of other processes that can lead to changes in cognitive functioning and sensory perception that may adversely affect driving (Marottoli and Drickamer, 1993; Stelmach and Nahom, 1992). This combination of factors is thought to contribute to older driver crash risk (Hakamies-Blomqvist, 1993; Stutts et al., 1998). Licensing authorities are the primary entity responsible for monitoring the medical fitness of their license holders. While it is important for licensing bodies to identify drivers who have conditions that place them at a heightened risk for crashes, at the same time, they should not unfairly restrict the mobility of disabled or aging drivers. Therefore, it is important that the licensing criteria for visual fitness to drive are based on scientific evidence establishing their effectiveness and predictive value for poor driving performance and unaceptable crash risk. The aim of this paper is to assess whether current licensing guidelines are consistent with the available scientific evidence on the effect of visual impairment on driving with a specific focus on older drivers. Methods. This article describes current licensing guidelines for vision from selected Western jurisdictions and reviews the available scientific evidence on visual impairment and driving performance on which such licensing decisions are based. Results. The findings of the review indicate that the predictive values of the vision tests commonly used for licensing decisions by the selected authorities are inconclusive. Discussion. The functional attributes of vision currently assessed for licensing do not adequately explain unsafe driving performance. Differences were observed across vision requirements for the selected jurisdictions, possibly reflecting the equivocal and inconclusive findings linking specific visual functions and impairment with crash risk. Setting benchmarks or performance thresholds on selected visual tests may be problematic for older drivers in particular, who are most vulnerable to underperforming. Driving involves a complex set of skills, and it is proposed that decisions about vision for safe driving need to be considered in the context of the drivers overall health and other functional abilities.

Development of a Standardised Occupational Therapy – Driver Off-Road Assessment Battery to Assess Older and/or Functionally Impaired Drivers

INTRODUCTION Research has been conducted over several years to develop a new off-road assessment battery referred to as the Occupational Therapy - Driver Off-Road Assessment Battery. This article documents the development of the Battery, and provides preliminary research evidence to support its content and predictive validity. METHODS Literature reviews and a focus group with nine driver assessor occupational therapists were undertaken, as well as data collection using the Occupational Therapy - Driver Off-Road Assessment Battery with 246 clients. A Classification and Regression Tree model was constructed to ascertain the predictive validity of the Battery, with fitness-to-drive as the outcome. RESULTS Twenty-one physical, 13 sensory and seven assessments of cognition/perception were identified as being reflective of the skills required for driving. Following rating of their psychometric properties, the best assessments were presented to focus group members. The driver assessors supported the inclusion of several assessments and encouraged the development of new assessments. A draft version of the Occupational Therapy - Driver Off-Road Assessment Battery was tested and found to have excellent predictive validity for client on-road performance of 82.6%. The Classification and Regression Tree model showed that client performance on tests included in the Battery should be used together, rather than in isolation, to support fitness-to-drive recommendations. CONCLUSION This research identified the most suitable physical, sensory and cognitive assessments to include in the Occupational Therapy - Driver Off-Road Assessment Battery, and provided support for its validity. The development of this standardised battery assists driver assessors to accurately and consistently assess and report the off-road driving capacity of clients.

Residual cannabis levels in blood, urine and oral fluid following heavy cannabis use

An understanding of tetrahydrocannabinol (THC) kinetics and residual levels after cannabis use is essential in interpreting toxicology tests in body fluids from live subjects, particularly when used in forensic settings for drug abuse, traffic and interpersonal violence cases. However the current literature is largely based on laboratory studies using controlled cannabis dosages in experienced users, with limited research investigating the kinetics of residual THC concentrations in regular high dose cannabis users. Twenty-one dependent cannabis users were recruited at admission to two residential detoxification units in Melbourne, Australia. After being provided with information about, and consenting to, the study, subjects volunteered to provide once-daily blood, urine and oral fluid (saliva) samples for seven consecutive days following admission, involving cessation and abstinence from all cannabis use. Blood and oral fluid specimens were analysed for THC and urine specimens for the metabolite THC-COOH. In some subjects THC was detectable in blood for at least 7 days and oral fluid specimens were positive for THC up to 78 h after admission to the unit. Urinary THC-COOH concentrations exceeded 1000 ng/mL for some subjects 129 h after last use. The presented blood THC levels are higher and persist longer in some individuals than previously described, our understanding and interpretation of THC levels in long term heavy cannabis users may need to be reconsidered.

Evaluating the use of prolonged video-EEG monitoring to assess future seizure risk and fitness to drive.

OBJECTIVE The use of prolonged video-electroencephalography monitoring (VEM), rather than routine electroencephalography (EEG), in predicting the risk of future seizures in patients with epilepsy is not well studied. A longer period of monitoring could be more likely to capture either ictal or interictal epileptiform activity. This information may better assist clinical decision making on driving fitness. The goal of this study was to evaluate the use of 6-hour prolonged VEM versus routine EEG in the assessment of future seizure risk and driving fitness for patients with epilepsy. METHODS Data on consecutive patients referred for 6-hour prolonged VEM were retrospectively analyzed. Criteria were developed that combined EEG findings and clinical factors to determine each patients fitness to drive. Seizure relapse outcomes were followed over 2 years. RESULTS Of 34 patients, 27 were considered safe to drive following prolonged VEM. Five (19%) of these 27 patients had seizure relapses; all had an obvious precipitant(s) identified including sleep deprivation, excessive alcohol, and missed medication doses. Seven of the 34 patients were deemed unsafe to drive. All seven (100%) had seizure relapses, with unprovoked seizures in four patients. The relative risk of seizure in patients deemed unfit to drive was 5.4 (P=0.00015). If only the routine EEG component of the recordings were used with the criteria, the relative risk would have been 3.4 (P=0.037), with nearly double the number of active drivers having seizures. The majority of patients (76%) in this study had idiopathic generalized epilepsy, with a relative seizure risk of 4.0 (P=0.002) for patients deemed unfit to drive in this subgroup. The focal epilepsy group was small (eight patients) and did not quite achieve statistical significance. CONCLUSION Six-hour VEM improves the evaluation of driving fitness by better predicting the risk of subsequent seizure relapse for idiopathic generalized epilepsy and possibly focal epilepsy. Prolonged monitoring is superior to routine EEG. Ongoing avoidance of seizure-provoking factors remains paramount to driving safety.

Epilepsy and driving: Current status of research

In many parts of the world, licensing guidelines state that drivers with medical conditions such as epilepsy are restricted or prohibited from driving. These guidelines are sometimes subjective and not strongly evidence-based, rendering the task of assessing fitness to drive a complex one. Determining fitness to drive is not only essential for maintaining the safety of individual drivers but has implications for the community at large. It is therefore important to review the current state of knowledge regarding epilepsy and driving in order to aid health professionals required to assess fitness to drive and to guide future research directions. This review outlines the functional impairments related to epilepsy and driving, treatment and management issues, motor vehicle crash risk for drivers with epilepsy, estimates of predicted seizure occurrence and concludes with a discussion of the international licensing guidelines and relevant legal issues. More comprehensive research, including investigation into the effects of antiepileptic medication on driving, could aid in the development of policies and guidelines for assessing fitness to drive.

Interrater Reliability of the Road Law and Road Craft Test as Part of the OT-DORA Battery for Off-Road Driver Assessment

Background: The Occupational Therapy Driver Off Road Assessment (OT-DORA) Battery is in development as a comprehensive off-road evaluation of fitness to drive. Although several psychometric properties of the Road Law and Road Craft Test (RLRCT) have been previously studied, interrater reliability must also be established to include this test in the battery. Aim: The aim of the study was to determine the interrater reliability of the RLRCT. Method: Three occupational therapy driver assessors independently scored 20 client responses on the 14-item RLRCT. Results: The interrater reliability for all items, except item 6, was found to be between 0.57 and 1.00. The scoring instructions for item 6 were revised and the interrater reliability rose from 0.42 to 0.77. Conclusion: The RLRCT has been found to be reliable when administered by different raters and is thus suitable for inclusion in the OT-DORA Battery. Ongoing research to confirm the psychometric properties of the RLRCT is required.

Drug-induced anisocoria in two detainees

Two suspects held by the police were examined for fitness to be interviewed. It was noticed that both had a persistent unilateral dilated pupil in the absence of a history of pre-existing disease or acute head injury. They subsequently admitted to misuse of eye drops. A brief review of the significance of anisocoria (unequal pupils) and drugs that may cause altered pupillary size follows.

Breath testing in patients with respiratory disability

The presence of chronic respiratory disease is sometimes claimed as a defence by drivers who refuse or fail a breath test. Trials have been conducted with two breath analysis instruments used in the state of Victoria, Australia in order to determine the respiratory parameters compatible with a satisfactory test. Patients with restrictive and obstructive conditions participated in the trial that was conducted in the respiratory unit of a large teaching hospital. The results showed that the evidential breath analyzer currently used in Victoria was able to accept breath samples from subjects at the limit of respiratory function likely to be encountered in drivers. It was also found that a subject capable of providing a breath sample for the current screening device should also be able to provide an evidential sample. The trials provided useful information in evaluating defences of inability to provide a breath sample due to respiratory incapacity.

Characteristics of motor vehicle crashes associated with seizure: Car crash semiology

Objective To examine the characteristics of seizure-related vehicle crashes (SRC). Method Using a nested case-control design, we identified and compared cases of SRC involving confirmed epilepsy patients with 137,126 non-seizure-related crash controls (NSRC) in the Australian state of Victoria. SRC were identified from approximately 20,000 epileptologist medical records by cross-referencing this source with the Victorian Police Traffic Incident database and the Road Crash Information System Database (RCISD). Results Seventy-one SRC involving 62 patients with epilepsy were identified. Thirty-seven SRC resulted in injury and could be identified in the RCISD and compared to NSRC. Seizure-related crashes typically involved a single vehicle (57% vs 29%, p < 0.001) carrying a sole occupant (95% vs 48%, p = 0.001). Most SRC began with an “out of control movement” (51% vs 10%, p < 0.001) and the subsequent collision type differed significantly between the groups (p < 0.001). The majority of SRC were a “collision with a fixed object” (54% vs 17%, p < 0.001) involving an “off path on straight” mechanism (48% vs 10%, p < 0.001). Regarding all 71 SRC, generalized as compared with focal epilepsy crashes involved younger drivers (p < 0.001), seizure-provoking factors (p = 0.033), and occurred earlier in the day (p = 0.004). Conclusions Given the distinct SRC features, we propose that clinicians, crash investigators, and driver licensing authorities incorporate collision characteristics into the overall assessment of suspected SRC. Further research should examine restricting driving immediately after risk periods as a harm-minimization strategy.