Karst and Passie highlight several problems in the discussion of the benefits of cannabis-based medications in pain medicine.
Most randomized controlled trials (RCTs) that have been conducted of oral sprays containing tetrahydrocannabinol (THC)/cannabidiol (CBD) were funded by the manufacturer of the preparation. As only one study of medical cannabis was included, however, a systematic review did not show any relevant differences of the different cannabis-based medications regarding their efficacy and tolerability in neuropathic pain (1). In order to base the discussion of the importance of medical cannabis on more solid data, publicly funded studies are required that compare the efficacy and tolerability of a) proprietary medicinal product containing defined doses of THC and/or CBD, b) types of cannabis flowers selected according to the physician’s experience, and c) established therapeutic approaches.
We agree that combining all chronic pain syndromes in systematic reviews of RCTs is problematic. For this reason, we differentiated—as far as was possible—in our review article by individual categories of pain syndromes.
Review articles have reached different conclusions about the quality of the evidence and benefits of cannabis-based medications. The stricter the inclusion criteria and the required quality of the evidence, and the more systematic the literature search, the more sobering the results (3). The US National Academies of Sciences, Engineering, and Medicine did not follow established standards in defining the evidence. The authors therefore qualify the conclusion as follows: “This hierarchy of evidence does not imply the magnitude of the observed effect or the importance of the health effect from an individual or population standpoint.” For a presentation that is of high methodological quality we refer readers to a recently published overview that was funded by the German Federal Ministry of Health (4).
On behalf of the authors
Prof. Dr. med. Winfried Häuser
Klinik Innere Medizin I
Conflict of interest statement
The author declares that no conflict of interest exists.
|1.||Petzke F, Enax-Krumova EK, Häuser W: [Efficacy, tolerability and safety of cannabinoids for chronic neuropathic pain: A systematic review of randomized controlled studies]. Schmerz 2016; 30: 62–88 CrossRef MEDLINE|
|2.||Häuser W, Fitzcharles MA, Radbruch L, Petzke F: Cannabinoids in pain management and palliative medicine—an overview of systematic reviews and prospective observational studies. Dtsch Arztebl Int 2017; 114: 627–34 VOLLTEXT|
|3.||Häuser W, Petzke F, Fitzcharles MA: Efficacy, tolerability and safety of cannabis-based medicines for chronic pain management—an overview of systematic reviews. Eur J Pain 2017; doi: 10.1002/ejp.1118. [Epub ahead of print] CrossRef|
|4.||Hoch E, Schneider M: Cannabis: Potenzial und Risiken. Eine wissenschaftliche Analyse (CaPRis). www.bundesgesundheitsministerium.de/fileadmin/Dateien/5_Publikationen/Drogen_und_Sucht/Berichte/Kurzbericht/171127_Kurzbericht_CAPRis.pdf (last accessed on 2 January 2018).|