Limitations of risk analysis in the determination of medical factors in road vehicle accidents.

The purpose of risk analysis in the determination of medical factors in road vehicle accidents is to evaluate the risks that are associated with different strategies for accident reduction, so that the subsequent decision making process can be based on a best assessment of the likely benefits. However, it is vital to appreciate the limitations of such an approach, especially where the conclusions depend heavily on the accuracy of the assumptions made. In this paper the assumptions used in some recent analyses concerned with incapacitation, epilepsy, hypoglycaemia and psycho-active medication are explored, and the additional information required to reduce the uncertainty in the estimation of risk indicated. The conclusions from this analysis do not invalidate the use of risk assessment, but draw attention to its limitations and show how a sensitivity analysis can help to identify those areas where more precise information is needed before such an approach can be used confidently in a policy setting.