Whiplash risk estimation based on linked hospital-police road crash data from France and Spain

To investigate potential risk factors for whiplash injury as a function of crash configuration and driver's characteristics, and to provide information on over-reporting and under-reporting of whiplash.

A case-control study of drivers involved in two-car injury collisions. Cases were drivers who had a diagnosis of whiplash injury, with or without another injury. Controls were drivers without diagnosed whiplash injury.

Hospital registries linked to police crash databases for Barcelona (Spain) and the "Département du Rhône" (France).

Relative risks of whiplash and 95% confidence intervals were estimated using a modified Poisson regression.

Of the 8720 drivers involved in car-to-car crashes recorded in the French database, 12.2% were diagnosed with whiplash; the corresponding figure in the Spanish database was 12.0% of 7558 drivers. Female drivers and drivers in rear-impact collisions were most likely to have a whiplash diagnosis, although the absolute number of whiplash cases was greater in front and side impacts. Wearing a seatbelt, being in a heavier car, and age greater than 65 years were associated with a lower risk of whiplash injury. Drivers with other injuries were also more often diagnosed as having a whiplash injury, except the most severely injured.

Devices aimed at reducing the occurrence of whiplash injuries, such as dynamic headrest systems, should be adapted to the characteristics of at-risk occupants, especially women, and should address the mechanics of front and side impacts in addition to rear impacts.