Benzodiazepine-related traffic accidents in young and elderly drivers

The relation of BZD use to impaired driving skills has been well established by both experimental and epidemiologic studies. There has been a concern that elderly people might be more affected than younger people, but for this the empirical evidence is less clear. The present study will examine the differences in risk of injurious traffic accidents after BZD use in older adults (60+) compared with those younger. Also the differences in effect of short acting and long acting BZD and, more tentatively, differences in effect of first-time and long term will be considered. The study design is an epidemiologic cohort study for which data was received from the Saskatchewan Health Data Bases. The study population consists of 225 796 persons above 20 with a first BZD prescription, and 97 862 controls. All first-time users were eligible for entering the repeat users cohort if they received three prescriptions within any 5 month period. New users increased their risk of injurious traffic accidents within the first 4 weeks of the BZD prescription at an OR = 3.1 (1.5-6.2). Persons under 60 had a risk of OR = 3.2 (1.3-8.1), while older people had OR = 2.8 (1.0-8.4). For individual BZD, flurazepam showed the largest increase in risk at OR = 5.1; stratified for age the OR was 6.1 for the under 60 and 3.4 for the over 60 age groups. The number of traffic accidents in the repeat use population was very small, but they hint at the possibility that repeat users have a lower risk than new users. These results need to be confirmed and the recommendations are that further studies be done to ferret out relations among the various potential influences of age, type of BZD and length of use. (C) 1998 John Wiley & Sons, Ltd.