J Clin Epidemiol Vol. 51, No. 5, pp. 377–384, 1998 0895-4356/98/$19.00 Copyright  1998 Elsevier Science Inc. All rights reserved. PII S0895-4356(98)00011-0 The Effect of Socio-Demographic and Crash-Related Factors on the Prognosis of Whiplash Susan Harder, 1 Martin Veilleux, 2 and Samy Suissa, 1,3,* 1 Department of Epidemiology and Biostatistics, McGill University, Montreal, Quebec, Canada; 2 Montreal General Hospital, Montreal, Quebec, Canada; and 3 Department of Medicine, Royal Victoria Hospital, Montreal, Quebec, Canada ABSTRACT. Whiplash injury, common after a motor vehicle crash, has a variable prognosis that is difficult to predict. To assess the role of various factors on this prognosis, we assembled a historical cohort of 3014 individuals who sustained a whiplash injury resulting from a motor vehicle crash in the Province of Quebec, Canada, in 1987 and were followed for 6 years. The data were obtained from the computerized databases created by the province’s universal automobile insurance plan and police accident reports. The recovery time from whiplash, as measured by duration of compensation, was the primary outcome. Socio-demographic and crash- related factors measured at the time of the crash were investigated. The median recovery time for the cohort was 31 days, with 22% recovering within a week and 3% still not recovered after 1 year. For the 1551 subjects with a whiplash injury only, the socio-demographic factors that were found to be independently associated with a slower recovery from whiplash in this cohort are female gender, older age, having dependents, and not having full-time employment. The significant crash-related factors are occupancy in a truck or bus, being a passenger in the vehicle, colliding with a moving object, and being in a head-on or perpendicular collision. We classified the subjects according to a prediction score ranging from 0 to 11, devised from these factors. Subjects with a score of 0 to 2, that is those who had at most two risk factors present, had the fastest median recovery time of 19 days compared with 71 days for subjects who had a score of 6 or more. We conclude that several socio- demographic and crash-related factors are independently associated with a slow and costly recovery from whip- lash injury. They are easily measurable at the time of the crash and combined so as to be simply incorporated in intervention programs aimed at early identification and management of whiplash patients with a poor prognosis. j clin epidemiol 51;5:377–384, 1998.  1998 Elsevier Science Inc. KEY WORDS. Claims data, compensation, epidemiology, motor vehicle crash, soft-tissue injury, trauma INTRODUCTION cult to predict [5], with symptoms tending to persist for at least 6 months in more than one-quarter of whiplash cases Motor vehicle crashes are a significant cause of morbidity [6–10]. Studies suggest that gender is not associated with a and mortality all over the Western world [1]. A common longer recovery time, but older age is [11]. With respect to injury among motor vehicle occupants involved in colli- vehicle-related factors, rear-end collisions [12] and the use sions is whiplash, originally named to describe the result of of a seatbelt [8] are reported to increase the recovery time. a rapid hyperextension and flexion of the muscles of the To date, few studies have investigated the simultaneous neck [2]. The incidence of whiplash varies greatly in differ- contribution of socio-demographic and vehicle or crash-re- ent parts of the world, with rates as high as 106 per 100,000 lated factors in predicting recovery from whiplash. In most yearly in Australia [3] and 70 per 100,000 in Quebec [4]. instances the study populations have been relatively small Moreover, the rate of compensation claims made to govern- and highly selected and thus unrepresentative of the general mental insurance agencies responsible for whiplash injuries population of whiplash subjects. Moreover, most of these also vary significantly, making up close to 20% of all com- studies used prevalent cohorts, in that subjects were entered pensation claims in Quebec, 68% in British Columbia, and in the cohort long after their injury, so that time zero was 85% in Saskatchewan [4]. unknown. Within the context of the work of the Quebec The prognosis of whiplash patients is variable and diffi- Whiplash-Associated Disorders (WAD) Task Force, we conducted a cohort study to describe the incidence and * Address for correspondence: Dr. Samy Suissa, Division of Clinical Epide- costs of WAD and to identify potential prognostic factors. miology, Royal Victoria Hospital, 687 Pine Avenue West, Ross 4.29, Mon- We found several socio-demographic and crash-related fac- treal, Quebec, Canada H3A 1A1. Accepted for publication on 5 January 1998. tors that were potentially associated with a longer recovery