Yet another study has been published that has investigated the factors involved in chronic whiplash pain. This study was done in Japan, and followed 6,167 adults who reported to their insurance company after a rear-end collision. None of the patients had neurological or radiographic signs. A wide range of social and accident variable data were collected.

One interesting finding was that older whiplash patients were not at a higher risk of developing chronic symptoms. "The relatively small [number] of cases found in older age groups is an important finding. If underlying degenerative disease were a significant predisposing cause of symptoms, then one would expect to find more cases in those age groups in which cervical spondylosis is prevalent. Therefore, these findings raise doubts about the role of degenerative disease in the production of head and neck symptoms."

The researchers reported that employment status had no effect on symptoms at six months post-injury, indicating that "biological factors were found to be more strongly associated with the prolongation of treatment."

Satoh S, Naito S, Konishi T, et al. An examination of reasons for prolonged treatment in Japanese patients with whiplash injuries. Journal of Musculoskeletal Pain 1997;5(2):71-84.