Medical conditions as a contributing factor in crash causation
Despite recognition that medical conditions contribute to the risk of crash involvement, little is understood about the mechanisms by which these conditions lead to drivers, riders and pedestrians being involved in motor vehicle collisions. This study involved in-depth at-scene investigation of 298 road crashes in the Adelaide metropolitan area in which at least one person was transported to hospital or fatally injured as a result of injuries sustained in the crash. Medical records for those attending hospital or undergoing post-mortem examination were checked for medical documentation providing evidence that a medical condition was a contributing factor in the crash. This information was then matched with the information gathered at-scene and during personal interviews to determine the extent to which the medical condition contributed to the crash, taking into account other factors. We found that almost half the drivers, riders and pedestrians (referred to as active participants) involved in the crashes had at least one pre-existing medical condition, and half of these individuals had two or more such conditions. Importantly, we found that a medical condition was the main causal factor in 13% of the casualty crashes investigated and accounted for 23% of all hospital admission and fatal crash outcomes. The findings highlight the role of medical conditions as a contributing factor in crash causation based on real crash data.