This paper evaluated the association between rear-end collisions and the risk of future neck or shoulder pain. Neck or shoulder pain subjects who had experienced a rear-end collision were compared to similar pain patients who had not been exposed to a collision.
Those who were involved in a rear-end collision were divided into two groups: those with an initial whiplash injury (232 patients) and those without an initial whiplash injury (204 patients). Two groups were selected from the unexposed patients to compare. All subjects were mailed a questionnaire seven years post-injury, inquiring about their neck and shoulder pain, and subjective general health.
The authors based their risk assessments on the ratio of prevalence among exposed patients compared with the unexposed patients. The relative risk of neck or shoulder pain in patients without an initial whiplash injury was 1.3, and the risk in those with an initial whiplash injury was 2.7. The authors write:
"Exposure to rear-end collision was associated with future neck or shoulder pain only if pain due to a whiplash injury was present from the beginning. In subjects with initial whiplash injury, the risk of neck or shoulder pain seven years after a rear-end collision was increased nearly threefold compared with that in a group unexposed to car collisions."
Berglund A, Nygren A, Jensen I, et al. The association between exposure to a rear-end collision and future neck or shoulder pain: a cohort study. World Congress on Whiplash-Associated Disorders 1999;p. 99.