Motor vehicle accidents (1973-6) in a cohort of Montreal drivers.

In 1973-4 nearly 10 000 Montreal drivers, interviewed by telephone, provided information about medical and associated factors and about driving habits, in particular annual mileage. Records of accidents suffered by these drivers in the Province of Quebec over 39 months (1973-6) were also collected. The 7634 current drivers, with appropriate permits, and all of whose data passed reliability edits, were placed into nine sets-that is, three classes: women; men with the usual permit; and men with a chauffeur's permit to drive taxis, heavy vehicles, etc; further subdivided into three age groups. Accident rates depended on mileage, but after allowance for differences in mileage, accident rates still varied with sex, type of permit, and age. No association of the risk of accidents and a medical or related factor was consistent over all nine sets of drivers. Of the 7634 drivers, 347 had had at least one accident causing injury or death in the 39 months from 1 January 1973. These "cases" were compared with 347 "referents," closely matched for sex, type of permit, age, and reported mileage, but without accident causing injury or death. Cases included higher proportion who worked irregular shifts, who were overweight, and who reported smoking while driving. Relative to the chance of a referent suffering any accident in the 39-month period, a case had at least double the risk of having an accident in addition to the index accident.