Influence of Chronic Illness on Crash Involvement of Motor Vehicle Drivers

4.4 CONCLUSION AND RECOMMENDATIONS
This review presents evidence in relation to medical conditions and driver risk. One of the most striking observations that can be made is that the quality and quantity of evidence does not do justice to the serious consequences associated with motor vehicle crashes. Methodological limitations were evident in most studies, including a lack of standardisation of inclusion criteria for medical conditions and unreliable measures of crash involvement (i.e. self-report).

The review of evidence for crash risk was compared with guidelines regarding fitness to drive from selected jurisdictions. These comparisons revealed a number of inconsistencies across the jurisdictions and in some cases the guidelines did not appear to reflect the available evidence for crash risk.
Information about management of medical conditions was also reviewed. Intuitively, it would be reasonable to expect that well-established treatments might reduce risk. Indeed, the treatment of sleep apnoea was shown to significantly reduce crash risk to the same level as those without the condition. However, for most conditions there was extremely limited evidence for this in the literature. In the case of treatments for psychiatric disorders, benzodiazepines and antidepressants (tricyclics) were found to increase risk. Other methods of management include special licensing conditions or restrictions. For example a driver diagnosed with visual impairment may drive only when wearing corrective lenses. A driver with diabetes may be required to take insulin on a regular basis. A driver who has lost a limb may only drive whilst wearing a prosthesis. In addition, self-regulation is also a potentially useful management approach. For example drivers with epilepsy are often advised not to drive if they are tired and to avoid precipitating factors such as emotional or physical stress. However, self-regulation is only likely to effective if the driver has insight into the factors that place them at risk. In the case of dementia and psychiatric illness, the capacity for insight is
likely to be impaired. Moreover, there is little evidence that specifically addresses the benefit of self-regulation in reducing crash risk.

In the light of the available information presented in this review, a number of recommendations can be made:

- Develop reliable methods of identifying and referring those who are potentially at-risk as a result of medical conditions;
- Promote public awareness, particularly amongst the driving population, about the known crash risks and effective management for particular medical
conditions or impairments. This is important particularly because most jurisdictions are reliant on self-referral or voluntary reporting of medical conditions. Hence the onus is on the driver to determine whether they have a condition that affects their driving.
- Improve knowledge within the health profession about the known crash risks and effective management for particular medical conditions or impairments;
- Develop and implement valid and standardised assessments to identify the functional impairments of drivers with specific medical conditions at an
increased risk;
- Review licensing guidelines for fitness-to-drive in the light of all available evidence regarding crash risk;
- Investigate the capacity for the use of medical technologies for more effective monitoring of driver risk (e.g., in-vehicle blood glucose monitoring system);
- Investigate the capacity for the use of adaptive technologies and intelligent transport systems (ITS) to enhance driver safety (e.g., safe following distance devices and rear collision warning and avoidance systems);
- Review of chronic alcohol and drug abuse in a broader framework, including drugs and alcohol abuse and high level dose/useage;
- Advance high-quality scientific knowledge linking medical conditions and crash risk in order to improve the evidence base for formulating policy about licensing
and fitness to drive.