1. The population-based overall annual incidence rate of compensated insurance claims for whiplash injury in Quebec in 1987 was 70 per 100 000 inhabitants. The incidence rate was generally higher among females and people aged 20-24. The overall incidence rate was generally comparable to that of other countries, but much lower than that found in Saskatchewan where the rate may be as high as 700 per 100 000. A possible explanation for this difference between the two provinces may lie in the contrasting no-fault insurance system in Quebec and tort system in Saskatchewan.

2. Female gender, older age, married/cohabital status and a greater number of dependents were the sociodemographic factors associated with a longer time of absence for whiplash. Being in a severe collision, in a vehicle other than a car or taxi, in a collision other than rear-end and not using a seat belt were the collision-related factors associated with a longer time of absence. The presence of multiple injuries was also an important prognostic factor.

3. Rear-end collisions and having one or more dependents were associated with a higher rate of relapse or recurrence of symptoms of whiplash subjects.

4. Of the more than 18 million Canadian dollars paid out by the SAAQ to the 1987 cohort of 4757 whiplash subjects, over 70% was paid for the replacement of regular income. Thus, the main portion of the total cost incurred by the SAAQ for whiplash is directly related to the duration of compensation.

5. The 26% of subjects with only a whiplash injury whose absence lasted between two and six months accounted for 38.5% of the costs, while the remaining 12.5% of patients still compensated six months after the collision accounted for 46% of the total costs paid out by the SAAQ. For the patients with multiple injuries besides whiplash, 15.3% of patients were still compensated six months after the event and they accounted for 60.4% of the total costs. Therefore, the financial burden of whiplash injury to the SAAQ results from the small number of persons who became chronic.