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Open Access Highly Accessed Research article

Alcohol and cannabis use as risk factors for injury – a case-crossover analysis in a Swiss hospital emergency department

Gerhard Gmel124*, Hervé Kuendig2, Jürgen Rehm3456, Nicolas Schreyer7 and Jean-Bernard Daeppen1

Author Affiliations

1 Alcohol Treatment Center, Lausanne University Hospital, Lausanne, Switzerland

2 Swiss Institute for the Prevention of Alcohol and Drug Problems, Lausanne, Switzerland

3 Research Institute for Public Health and Addictions, Zurich, Switzerland

4 Centre for Addiction and Mental Health, Toronto, Ontario, Canada

5 Public Health Sciences, Faculty of Medicine, University of Toronto, Canada

6 Clinical Psychology and Psychotherapy, Technische Universität Dresden, Dresden, Germany

7 Interdisciplinary Center of Emergencies, Lausanne University Hospital, Lausanne, Switzerland

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BMC Public Health 2009, 9:40  doi:10.1186/1471-2458-9-40

Published: 29 January 2009



There is sufficient and consistent evidence that alcohol use is a causal risk factor for injury. For cannabis use, however, there is conflicting evidence; a detrimental dose-response effect of cannabis use on psychomotor and other relevant skills has been found in experimental laboratory studies, while a protective effect of cannabis use has also been found in epidemiological studies.


Implementation of a case-crossover design study, with a representative sample of injured patients (N = 486; 332 men; 154 women) from the Emergency Department (ED) of the Lausanne University Hospital, which received treatment for different categories of injuries of varying aetiology.


Alcohol use in the six hours prior to injury was associated with a relative risk of 3.00 (C.I.: 1.78, 5.04) compared with no alcohol use, a dose-response relationship also was found. Cannabis use was inversely related to risk of injury (RR: 0.33; C.I.: 0.12, 0.92), also in a dose-response like manner. However, the sample size for people who had used cannabis was small. Simultaneous use of alcohol and cannabis did not show significantly elevated risk.


The most surprising result of our study was the inverse relationship between cannabis use and injury. Possible explanations and underlying mechanisms, such as use in safer environments or more compensatory behavior among cannabis users, were discussed.