This was statistically significant both before and after adjusting for various confounding variables (age, number of miles driven annually, etc.). However, drivers of 75 and more who had taken the refresher course were at the same risk as drivers who had not. The same tendency, although weaker and non-significant, was found for single-vehicle accidents. It seems that the refresher course has a beneficial effect on safe mobility only if the driver completes the course before 75. One practice used in Switzerland is described as a representative example, there.