The medical effects of seat-belt legislation in the United Kingdom: the collection of the data.

On 31 January 1983, it became compulsory for most drivers and front-seat passengers in vehicles with an unladen weight of less than 3 tons to wear seat-belts in the United Kingdom. This study was devised in order to provide definitive information on any changes in the injury patterns car and light goods vehicle occupants have suffered resulting from the law. Originally it was expected that this aim would be achieved by collecting data from hospitals for a year before and a year after the introduction of the law. However, it proved impossible to collect data uniformly through the hospital system on all fatally injured casualties, and, in consequence, a parallel study of injuries sustained by fatalities was undertaken using coroners' records. The methodology of the hospital and fatal studies were very similar, excepting that the latter covered only two corresponding 6-month periods in 1982 and 1983.