title: The role of driver sleepiness in car crashes: a systematic review of epidemiological studies.
abstract: To assess the available evidence for a causal role of driver sleepiness in car crashes or car crash injury, and to quantify the effect, a systematic review of the international literature was conducted. The review included all studies with a fatigue-related exposure measure, a crash or crash injury outcome measure and a comparison group, regardless of publication status, language or date of the study. Eighteen cross-sectional studies and one case-control study fulfilled the inclusion criteria. The fatigue-related exposures investigated in these studies were sleep disorders (n = 14), shift work (n = 2), sleep deprivation/fragmentation (n = 1), and excessive daytime sleepiness (n = 2). Only one study used an injury outcome measure. Studies were limited in their ability to establish a causal relationship by their design, by biases, and in many cases, by small sample sizes. The better quality cross-sectional studies were suggestive of a positive relationship between fatigue and crash risk, but could not provide reliable estimates of the strength of the association. The case-control study provided moderately strong evidence for an association between sleep apnoea and risk of driver injury, with an adjusted odds ratio of 7.2 (95% confidence interval 2.4-21.8). We conclude that the direct epidemiological evidence for a causal role of fatigue in car crashes is weak, but suggestive of an effect. To estimate the burden of injury due to fatigue-related crashes in the population, information is required from well-designed observational epidemiological studies about the prevalence of fatigue in the car driving population and the size of the risk this confers.
authors.affiliation: Injury Prevention Research Centre, Department of Community Health, The University of Auckland, New Zealand. j.connor@auckland.ac.nz
authors.forename: J
authors.initials: J
authors.lastname: Connor
authors.forename: G
authors.initials: G
authors.lastname: Whitlock
authors.forename: R
authors.initials: R
authors.lastname: Norton
authors.forename: R
authors.initials: R
authors.lastname: Jackson
mesh_terms: D000063:Accidents, Traffic / Q000517:prevention & control / Q000706:statistics & numerical data*; D001334:Automobile Driving; D005221:Fatigue; D006801:Humans; D012107:Research Design; D012894:Sleep Stages