Risk Factors of Whiplash, Crash Factors

In this study, researchers interviewed 251 drivers involved in rear-end collisions that occurred less than one year before the interview. The objective was to determine which accident and occupant variables determined whiplash symptomatology.

Of the interviewed drivers:

• 35% reported a whiplash injury arising from the collision.
• Consistent with numerous other studies, women were more likely to report whiplash symptoms than were men; 25% of men reported whiplash, while 44% of women did.
• Two thirds of the whiplash occupants had consulted a health care provider, but only three drivers had gone to the emergency room after the accident.
• 40% of the whiplash patients reported a restriction of their daily activities.
• 23% of the whiplash patients had symptoms for at least three months.

The researchers also found the following variables were more likely to result in whiplash injury:

• “Female sex and a history of neck injury were the only statistically significant predictors of ‘whiplash’ occurrence. The relative risk of ‘whiplash’ occurring in drivers reporting a history of neck injury was more than twice that of drivers with no history. For women, the risk of ‘whiplash’ was approximately twice that of men. Age, occupational status and educational attainment were not significant predictors of ‘whiplash’ occurrence.”
• “Vehicle masses appeared to have an influence on the risk of ‘whiplash’ occurrence. The relative risk of occurrence in drivers of light vehicles (<1100 kg [2420 lb.]) was 1.43 times that for drivers of heavy vehicles (³1300 kg [2860 lb.]); this relative risk fell just short of statistical significance…The relative risk estimates relating to the weight of the striking vehicle showed a pattern of decreasing risk on injury with decreasing mass of the striking vehicle, and there was a positive association between the weight of the striking vehicle relative to the driver’s vehicle and the risk of ‘whiplash’ injury, as indicated by the trend in the relative risks over the relative vehicle-weight categories.” The relationship between striking vehicle vs. target vehicle mass has been hypothesized by engineers as a risk factor for injury, but this is the first study to actually see the relationship in a group of patients.
• “There was a 9 per cent increase in the risk of ‘whiplash’ injury in drivers who were not aware of the impending collision.” Although it did not reach statistical significance, “Compared with drivers reporting two or more sources of forewarning, those who had only one source had a 17 per cent increase in incidence, while those who reported no forewarning had a 20 per cent increase.” These findings are also consistent with the hypotheses of whiplash experts who predict that the absence of forewarning results in increased tissue damage because of low muscle tone.

Dolinis J. Risk factors for ‘whiplash’ in drivers: a cohort study of rear-end traffic crashes. Injury 1997;28(3):173-179.