Introduction
Opioids are commonly prescribed for chronic pain management and although
data support their role for managing acute and cancer-related pain, the
evidence to support use in chronic pain is not
robust.1–4 Prescription opioid misuse has contributed
to a widespread opioid overdose crisis resulting in the deaths of
hundreds of thousands of individuals worldwide.5,6
Medical cannabis containing different concentrations of cannabinoids –
such as Δ9-tetrahydrocannabinol (THC) and cannabidiol
(CBD) – is increasingly being used for the management of chronic
pain.7,8 Cannabinoids have a lower risk for dependence
compared with opioids and the predicted median lethal dose for THC is
>1000 fold higher than the effective
dose.9–11 Previous studies have found that
cannabinoids can improve pain related-outcomes, quality of life and,
importantly, have an opioid-sparing effect.7,12–19 In
addition, it has been reported that patients commonly use medical
cannabis as a substitute for opioid medication.20–23However the effectiveness of cannabis substitution for opioids is not
universally observed.24,25
Although these findings are noteworthy, the majority of clinical studies
investigating cannabis and cannabinoids as substitutes or adjuncts to
opioids are cross-sectional or small sample-size randomized controlled
trials. This lack of high-quality evidence makes providing classical
evidence-based recommendations inaccessible. Despite the paucity of
clinical trial evidence, physicians and patients are using cannabis to
support opioid tapering. In many countries, patients with chronic pain
have access to cannabis, and patients have reported self-administering
cannabis to reduce their opioid dose in the absence of clinical
guidance.22,26,27
Although cannabis has a lower risk of dependence compared to opioids, it
is not an inert therapy.28–31 At high doses,
CBD-related side effects can include fatigue, diarrhea, and changes in
appetite and weight.32 THC-related side effects can
include sedation, syncope, tachycardia, risk of cannabis-use disorder,
psychosis, and anxiety.8,33 With patients having
access to prescribed cannabinoids and self-treating with cannabis to
reduce their opioid dose, clinical guidance on safe cannabinoid
initiation and titration is urgently required. Randomized
placebo-controlled clinical trials examining how to co-manage
cannabinoids and opioids are unlikely to be provided in the near future.
Hence there is an immediate unmet need for guidance on this
topic.34
To provide guidance to health care professionals on how to safely manage
opioids and cannabinoids in patients with chronic pain, we employed a
modified Delphi process to develop a consensus-based guidance algorithm.
The modified Delphi process has been used extensively in health care
settings to provide consensus-based recommendations surrounding
important clinical questions.35 A previous Delphi
study related to opioids and cannabis was undertaken between 2015 and
2016 and aimed to develop consensus guidelines for responding to
patients on long term opioids using cannabis, however, the experts
disagreed on many of the proposed topics.36
The purpose of the present initiative was to develop consensus-based
recommendations on 1) when and how to safely initiate and titrate
cannabinoids in the presence of opioids, 2) when and how to safely taper
opioids in the presence of cannabinoids, and 3) how to monitor patients
and evaluate clinical outcomes when treating with opioids and
cannabinoids.