Abstract
BackgroundAlthough cannabis and cannabinoids are widely used with therapeutic purposes, their claimed efficacy is highly controversial. For this reason, medical cannabis use is a broad field of research that is rapidly expanding. Our objectives are to identify, characterize, appraise, and organize the current available evidence surrounding therapeutic use of cannabis and cannabinoids, using evidence maps.MethodsWe searched PubMed, EMBASE, The Cochrane Library and CINAHL, to identify systematic reviews (SRs) published from their inception up to December 2017. Two authors assessed eligibility and extracted data independently. We assessed methodological quality of the included SRs using the AMSTAR tool. To illustrate the extent of use of medical cannabis, we organized the results according to identified PICO questions using bubble plots corresponding to different clinical scenarios.ResultsA total of 44 SRs published between 2001 and 2017 were included in this evidence mapping with data from 158 individual studies. We extracted 96 PICO questions in the following medical conditions: multiple sclerosis, movement disorders (e.g. Tourette Syndrome, Parkinson Disease), psychiatry conditions, Alzheimer disease, epilepsy, acute and chronic pain, cancer, neuropathic pain, symptoms related to cancer (e.g. emesis and anorexia related with chemotherapy), rheumatic disorders, HIV-related symptoms, glaucoma, and COPD. The evidence about these conditions is heterogeneous regarding the conclusions and the quality of the individual primary studies. The quality of the SRs was moderate to high according to AMSTAR scores.ConclusionsEvidence on medical uses of cannabis is broad. However, due to methodological limitations, conclusions were weak in most of the assessed comparisons. Evidence mapping methodology is useful to perform an overview of available research, since it is possible to systematically describe the extent and distribution of evidence, and to organize scattered data.
Highlights
Cannabis and cannabinoids are widely used with therapeutic purposes, their claimed efficacy is highly controversial
Cannabis sativa produces more than 100 phytocannabinoids and the biosynthesis of these substances depends on genomic background and specific environmental conditions [4]
All but one systematic reviews (SRs) assessed the effectiveness of cannabis or cannabinoids, while the remaining SR evaluated the cannabinoids adverse events only [19]
Summary
Cannabis and cannabinoids are widely used with therapeutic purposes, their claimed efficacy is highly controversial. For this reason, medical cannabis use is a broad field of research that is rapidly expanding. Cannabis sativa produces more than 100 phytocannabinoids and the biosynthesis of these substances depends on genomic background and specific environmental conditions [4]. The existence of many molecules, which possibly modulate endocannabinoid system, complicates the scenario [5]. These are the reasons why, research on C. sativa is complex and difficult. Cannabis has a highrisk profile and its medical use is highly controversial, even for therapeutic reasons. Despite the adverse effects of cannabis use such as risk of developing cannabis dependence, exacerbation of cardiovascular disease, precipitation of psychotic disorders [7], and criticism to the evidence supporting its use for medical conditions, several governments have authorized the medical use of marijuana in countries such as Canada, the Czech Republic, Germany, Italy, the Netherlands, and 23 US states [8,9,10]
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