Cannabis-related hospitalizations: unexpected serious events identified through hospital databases

center dot The general knowledge on cannabis toxicity has improved, but quantitative data are still lacking. center dot Little is known about the somatic complications associated with cannabis exposure. Available data rest upon case reports and only a few studies have been conducted in this field. center dot Psychiatric disorders related to cannabis exposure are somehow still controversial. WHAT THIS STUDY ADDS center dot Quantitative estimates are key to comprehending the risks of medical outcomes in cannabis users, in particular the somatic complications of use. Our study suggests that cannabis use has to be linked to serious health defects, particularly neurological and cardiovascular disorders. center dot Our study gives estimates of the annual incidence of cannabis-related hospitalizations. center dot Our study should contribute to enhancing the medical management of cannabis using patients. AIMS Cannabis is the most prevalent illicit drug used worldwide and can be responsible for serious health defects in users. However, the risk related to cannabis consumption is not well established. The present study aimed to assess cannabis-related adverse events leading to hospitalization, and to estimate the corresponding annual risk for consumers. METHODS Participants were patients admitted to the public hospitals in the Toulouse area (France) between January 2004 and December 2007 in relation to the use of cannabis. Reasons for admission and other occurring events were identified through hospital discharge summaries. We described all observed adverse events (AEs) and estimated their regional incidence on the basis of cannabis consumption data. RESULTS We included 200 patients, and identified a total of 619 adverse events (AEs), one of which was lethal. Psychiatric disorders involved 57.7% of patients and accounted for 18.2% of AEs. Most frequent outcomes were central and peripheral nervous system disorders (15.8% of AEs), acute intoxication (12.1%), respiratory system disorders (11.1%) and cardiovascular disorders (9.5%). We estimated that in 2007 the incidence of cannabis-related AEs in the Midi-Pyrenees region ranged from 1.2 per 1000 regular cannabis users (95% confidence interval (CI) 0.7, 1.6) to 3.2 (95% CI 2.5, 3.9). CONCLUSIONS Cannabis use is associated with complications, considered to be serious since they lead to hospitalization. Beyond the well-known and widely investigated psychiatric events, serious cerebro and cardiovascular complications have been identified. These findings contribute to improve the knowledge of cannabis-related adverse events.