A protocol for the systematic review and meta-analysis of studies in which cannabinoids were tested for antinociceptive effects in animal models of pathological or injury-related persistent pain

INTRODUCTION: The International Association for the Study of Pain has established a global task force to comprehensively investigate the use of cannabinoids and cannabis-based medicines for pain management. This systematic review, the first in this field, will assess the preclinical literature that investigates the antinociceptive effects of cannabinoids, cannabis-based medicines, and endocannabinoid system modulators in animal models of tissue damage, inflammation, or neuropathy. METHODS: A systematic electronic search of 3 online databases will identify relevant studies in which cannabinoids, cannabis-based medicines, and endocannabinoid system modulators have been tested in animal models of injury-related or pathological persistent pain. Data will be extracted for pain-associated behavioural outcomes, study design, and the reporting of measures to avoid bias. Standardised mean difference meta-analysis will be used to provide summary estimates of efficacy, with the effects of study quality and study design explored using stratified meta-analysis. PERSPECTIVE: The evaluation of the preclinical evidence will quantify the antinociceptive effects of cannabinoids on pain behaviour in animal models of pathological pain in an effort to quantify the presence and prevalence of analgesic efficacy. It will also provide an understanding of the strengths and weaknesses of the preclinical field and inform an agenda for future research.