This cohort study evaluated 2,810 whiplash patients' demographics and accident details to determine the effect on recovery. The study assessed gender, age, marital status, employment, income, and number of dependents. As well, the researchers examined the type of crash, the type of vehicle the subject was in, the severity of the crash, the seatbelt use, and the speed limit at the location of the crash. Additional attention was noted if there were reports of injuries in addition to whiplash.

The following factors were found to play a role in delayed recovery:

Female gender. Women were 15% slower at recovering than were men.
Older age had a dramatic effect on recovery. For every decade increase in age, the time to recovery was slowed by 14%!
Having dependents slowed recovery by 11%.
Not having full-time employment increased recovery time by 12%.
Being a passenger was also more risky than being the driver—passengers were 19% slower to recover. One reason may be that passengers are less likely to be aware of an impending collision, and are not able to shield their necks from injury.

There were some serious limitations in the study. Since the authors evaluated files on whiplash patients by using a claims database, certain key factors could not be determined with every patient. The direction of the collision, the position of the subject's neck at the time of collision, and the use of the vehicle's safety features (such as the head restraint) play important roles in evaluating whiplash injury, but were not included in the author's assessments.

Also, the researchers used the diagnosis of 'whiplash' quite liberally. They make a point of clarifying how they qualify and use the term whiplash:

"Strictly speaking, the term 'whiplash' was originally intended to describe the mechanism of injury caused by the rapid hyperextension and flexion of the muscles of the neck, as commonly experienced by motor vehicle occupants involved in rear-end collisions. However, the word whiplash has since entered into common usage to describe injury to the soft tissue of the neck or cervical spine resulting from motor vehicle crashes, regardless of the specific mechanism by which the injury occurred, and is essentially used in this way in the present study."

This statement calls into question if all subjects actually had whiplash, and subsequently, if the author's findings are indicative and trustworthy. Yet, the researchers conclude since these factors are easily measurable, "they can help the identification of whiplash patients with a poor prognosis and be simply incorporated in early intervention programs aimed at managing these patients."

Harder S, Veilleuz M, Suissa S. The effect of socio-demographic and crash-related factors on the prognosis of whiplash. Journal of Clinical Epidemiology 1998; 51(5):377-384.

Whiplash: Social and Crash Factors