Road traffic accident risk related to prescriptions of the hypnotics zopiclone, zolpidem, flunitrazepam and nitrazepam

Gustavsen, Ingebjørg; Bramness, Jørgen G.; Skurtveit, Svetlana; Engeland, Anders; Neutel, Ineke; Mørland, Jørg

doi:10.1016/j.sleep.2007.11.011

« Previous Next »Sleep Medicine
Volume 9, Issue 8 , Pages 818-822, December 2008

Road traffic accident risk related to prescriptions of the hypnotics zopiclone, zolpidem, flunitrazepam and nitrazepam

Ingebjørg Gustavsen
- Division of Forensic Toxicology and Drug Abuse, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway
- Corresponding author. Tel.: +47 23 40 78 00; fax: +47 23 40 78 78.
Jørgen G. Bramness
- Department of Pharmacoepidemiology, Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway
Svetlana Skurtveit
- Department of Pharmacoepidemiology, Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway
- Department of Pharmacy, University of Tromsø, Norway
Anders Engeland
- Department of Pharmacoepidemiology, Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway
- Department of Public Health and Primary Health Care, Section of Epidemiology and Medical Statistics, University of Bergen, Bergen, Norway
Ineke Neutel
- Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Canada
Jørg Mørland
- Division of Forensic Toxicology and Drug Abuse, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway
- Institute of Pharmacology, University of Oslo, Oslo, Norway

Received 24 September 2007; received in revised form 12 November 2007; accepted 13 November 2007.

Abstract

Background

Despite the high prescription rate of benzodiazepine-like hypnotics (z-hypnotics), there is limited information on the road traffic accident risk associated with the use of these drugs. We wanted to investigate whether filling a prescription for zopiclone or zolpidem was associated with increased risk of road traffic accidents at a national population level. Nitrazepam and flunitrazepam were used as comparator drugs.

Method

All Norwegians 18–69 years (3.1 million) were followed-up from January 2004 until the end of September 2006. Information on prescriptions, road traffic accidents and emigration/death was obtained from three Norwegian population-based registries. The first week after the hypnotics had been dispensed was considered to be the exposure period. Standardized incidence ratios (SIRs) were calculated by comparing the incidence of accidents in the exposed person-time to the incidence of accidents in the unexposed person-time.

Results

During exposure, 129 accidents were registered for zopiclone, 21 for zolpidem, 27 for nitrazepam and 18 for flunitrazepam. The SIRs were (SIR for all ages and both sexes combined; 95% CI): z-hypnotics (zopiclone+zolpidem) 2.3; 2.0–2.7, nitrazepam 2.7; 1.8–3.9 and flunitrazepam 4.0; 2.4–6.4. The highest SIRs were found among the youngest users for all hypnotics.