Psychoactive substances and violent offences: A retrospective analysis of presentations to an urban emergency department in Switzerland

BACKGROUND: Psychoactive substances are often regarded as causal factors contributing to violent injuries, sexual abuse and homicides. While these effects have been demonstrated for some substances (e.g. cocaine), current available data for others are more controversial (e.g. cannabis) or very limited (e.g. ecstasy). AIMS OF THE STUDY: To collect data on the type and frequency of psychoactive substance use in cases of emergency department (ED) presentations related to interpersonal violence. METHODS: Retrospective study at the University Hospital of Bern, Switzerland, between May 2012 and June 2016. The study covered cases of violent crime associated with psychoactive substances. Cases of isolated ethanol intoxication, suicide attempts, and substance use for medical purposes were excluded. RESULTS: The study included 103 cases among the 164,846 ED attendances. In the majority of the cases, the type of violence was bodily force (52%) related to urban violence (83%). The mean patient age was 29 years and 79% were male. 63% of the patients reported use of more than one drug; alcohol co-use was reported in 60% of the cases. Besides alcohol, the substances most often reported were cannabis (50%) and cocaine (21%). Alcohol and cannabis was also the most commonly reported substance combination (36% of the total cases). Urine drug screening was performed in 34% of the cases and cannabis and cocaine were the most commonly detected substances (46% and 19%, respectively). There were no cases of novel substances. 23% of the patients were admitted to a hospital ward, 10% to a psychiatric clinic. CONCLUSION: Cannabis and cocaine were, besides alcohol, the substances most often reported in ED presentations related to offences of violence. Because of the high prevalence of alcohol co-use, no final conclusions can be drawn on the contribution of single substances.