Understanding the epidemiology and perceived efficacy of cannabis use in patients with chronic musculoskeletal pain | Journal of Cannabis Research
In this study, more than one in five patients presenting to an orthopaedic surgeon with chronic MSK pain had used or was currently using cannabis to manage their chronic MSK pain. Consistent with previous self-reported studies, the majority of these patients perceived cannabis to provide effective pain management (Ajrawat et al. 2022; Meng et al. 2021). More than half (57%) claimed cannabis to be more effective than other analgesic medications, and 40% reported decreasing their use of other analgesic medications since starting cannabis use. Only 26% of cannabis users reported that a physician recommended the use of cannabis to manage their chronic MSK pain, and 23% were unaware of the composition of the cannabis they were consuming. Among non-users, 65% expressed an interest in using cannabis for managing their chronic MSK pain but often reported that they lacked knowledge regarding efficacy, access, usage, and composition, as well as the associated stigma.
We found that 23% of chronic MSK pain patients have used or are using cannabis to manage their pain, of which the majority are current users (72%). This rate of cannabis use among chronic MSK pain patients in the present study is considerably higher than the cannabis use rates reported in past studies with similar patient populations. For instance, two different studies, one from Canada and another from the United States, indicated that 4% of patients undergoing orthopaedic procedures used cannabis (Liu et al. 2019; Medina et al. 2019). Similarly, a 2014 Canadian study reported that approximately 3% of rheumatology patients were cannabis users (Ste-Marie et al. 2016). Yet, a more recent study conducted in Canada revealed that 29% of individuals with upper extremity conditions were presently utilizing cannabis, primarily for the purpose of pain management (Greis et al. 2022). The difference in prevalence between the previous studies from 3-6 years ago and the current study is largely due to the legalization of cannabis in Canada in October 2018, resulting in potential changes in attitudes towards and acknowledgment of use and more permissive access to cannabis without stigma and/or legal implications. In fact, a study assessing data from the National Cannabis Survey (NCS) revealed that in the months preceding legalization, 19% of Canadian respondents intended to try cannabis or increase their cannabis use following legalization (Sandhu et al. 2019). Complementing this, a 2014 US survey found that 13.5% of people would consume cannabis more frequently if legalized (Cohn et al. 2017). Additionally, the anonymous self-reported nature of the current study may have also allowed patients to feel comfortable disclosing their cannabis, resulting in the higher rate we observed.
The strongest predictors of those who would use cannabis for managing their chronic MSK pain, were patients with a history of recreational cannabis use and the presence of long-term chronic pain. These findings are consistent with previous reports examining cannabis use in various patient populations (Liu et al. 2019; Medina et al. 2019; Sandhu et al. 2019; Bhashyam et al. 2019). It was found that previous recreational cannabis use was associated with a more than tenfold increase in the odds of using cannabis to manage chronic MSK pain. This was unsurprising as current cannabis use has been shown to strongly influence one’s perceptions of risk, stigma, and acceptability (Rudski 2014). Features consistent with the diagnosis of a chronic pain syndrome, such as frequent pain clinic visits and longer pain duration, were also strong predictors of cannabis use in the current cohort, suggesting that patients with chronic MSK pain are possibly unsatisfied with conventional treatments and seeking alternative pain therapies. Lastly, younger age was not a predictor of using cannabis for the management of chronic MSK pain, when controlling for factors such as opioid consumption, depression status, and the duration of pain. This finding is inconsistent with past studies which have indicated that the incidence of any cannabis use (medical or recreational) generally declines with increasing age (Rotermann and Page 2018; Sampasa-Kanyinga et al. 2018). Typically, it is assumed that younger age is associated with cannabis use, which is likely because the belief among younger adults is that cannabis use is socially acceptable, not addictive, and not harmful (Kandel 2002; Keyhani et al. 2018; Ware et al. 2003). However, there may be several potential reasons for this discrepancy. First, the current study’s cohort is older overall (mean age >50 years) and includes fewer young adults that would typically report a greater prevalence of use as compared to elderly patients. Second, this finding may suggest a growing acceptance among older patients regarding the role of cannabis use for the purpose of managing medical issues, which may be the result of the legalization in Canada, increasing societal acceptance, and improvements in accessibility of non-inhaled cannabis products.
In this study, over 85% of cannabis users perceived it to be effective in managing their chronic MSK pain and improving their sleep and anxiety-related symptoms. Several studies have also noted similar rates of perceived effectiveness in chronic pain patients (Heng et al. 2018; Miller and Miller 2017; Mucke et al. 2018). One study with 937 orthopaedic outpatients found that cannabis use was significantly associated with decreased pain intensity and better lower extremity activity scores (Medina et al. 2019). In a prospective observational study of chronic orthopaedic pain patients, medical cannabis use was associated with significant clinical improvements in VAS pain scores, global physical health and mental health, and quality of life within three months but plateaued at the 6 and 12 month follow-up periods (Greis et al. 2022). Furthermore, cannabinoids were found effective in all eight studies from a systematic review that evaluated chronic pain stemming from orthopedic etiologies (Vivace et al. 2021). Despite preliminary evidence suggesting cannabis’ pain management potential, most studies have short-term follow-ups with relatively small sample sizes. Moreover, significant heterogeneity exists among studies with regards to dosage, routes of administration, composition, frequencies, and patient populations, justifying the need for further investigations to elucidate the true efficacy of cannabis for the management of chronic MSK pain.
Several interesting observations were noted herein: a quarter of cannabis users had no knowledge of the current cannabis product they were consuming and only a third of users procured their cannabis from a Health Canada licensed provider. A study with upper extremity orthopaedic patients indicated that approximately 46% of patients felt more comfortable discussing their cannabis use with their physician after legalization (Sims et al. 2022). From a recent survey study, 86% of orthopaedic patients that were characterized as cannabis users stated that they would be willing to stop consuming cannabis if their surgeon stated it would adversely impact their surgery (Carney et al. 2020). These observations highlight the dire need for improved oversight and regulation of the medicinal cannabis industry (Craft et al. 2020; Freeman and Lorenzetti 2020). In the present study, 23% of cannabis users were unaware of their cannabis composition. Greis and colleagues reported similar findings with 23-29% of orthopaedic patients being able to estimate the cannabis composition of their inhaled or oral cannabis products (Greis et al. 2022). In our study, the most frequent modes of administration among cannabis users were the ingestion of oils (57%), smoking (36%), and vaporizing (32%). Similar to our results, a previous report indicated that most orthopaedic patients preferred oral or sublingual administration of cannabis followed by inhalation to manage their chronic pain (Greis et al. 2022). In contrast, Carney et al reported that smoking was the most common mode of administration, followed by edible products, and vaporizing (Carney et al. 2020). Although most patients in the present study reported cannabis to be effective, the varying compositions, dosages, frequencies, and routes of administration, suggests that placebo may mitigate some of the perceived efficacy. As such, there is a need for large scale observational studies where the dosages and route of administration are standardized. This could then lead to meaningful placebo-controlled comparative studies in similar patient populations to determine the effectiveness on symptom management.
Historically, common first-line pharmacologic treatments such as nonsteroidal anti-inflammatory drugs (NSAIDs) have been prescribed to alleviate chronic pain. However, NSAIDs have been associated with intolerance and serious adverse events in some patients including upper gastrointestinal bleeding or perforation (Bjordal et al. 2004; Langman et al. 1994). Opioids have also been prescribed to manage chronic MSK pain when conventional treatments have failed, so it is not surprising that individuals with chronic MSK pain are amongst the highest prescription opioid users (Ashaye et al. 2018; Manchikanti et al. 2012). However, long-term opioid use has been associated with greater pain intensity, poorer outcomes, and unintendedly increases the risk of developing an opioid use disorder, diversion, and fatal overdose (Bot et al. 2014; Dunn et al. 2010; Koehler et al. 2018; Noble et al. 2010). Cannabis has been suggested as a potentially safer analgesic therapy. In the present study, approximately 40% of our patients reported that their analgesic medications were reduced after initiating cannabis. A similarly designed study by Sims and colleagues with reported that 51% of orthopaedic patients felt that cannabis was safer than their prescription analgesics. (Sims et al. 2022) Further, Greis et al reported that 31% of chronic orthopaedic pain patients discontinued benzodiazepines, 73% either ceased or decreased opioid consumption, and noted a 23.4% reduction in 6-month total opioid prescription with cannabis use (Greis et al. 2022). Moreover, a systematic review evaluating the use of cannabinoids in orthopaedic patients found that the five of the seven studies noted an opioid sparring effect and two of the seven studies reported complete cessation of opioid use at the 6 to 12 month follow-up period (Vivace et al. 2021). Prior surveys of American and Canadian cannabis users reported that substituting cannabis for opioids resulted in improved pain management, decreased adverse effects, and eased opioid withdrawal symptoms. (Lucas and Walsh 2017; Vyas et al. 2018)
It is noteworthy that cannabis users exhibited a constellation of comorbid conditions, including a higher prevalence of depression and pain, an increased number of painful bodily areas, longer pain durations, and more frequent visits to pain clinics/specialists when compared to non-cannabis users. This observation prompts us to consider the possibility that cannabis use may have arisen as a response to elevated levels of pain and dissatisfaction with existing therapeutic modalities. It is possible that a significant proportion of cannabis users turned to cannabis to seek relief from their heightened pain burden, which appears refractory to conventional treatments. Furthermore, we observed that cannabis users, despite experiencing greater pain, tended to employ a broader array of medications, such as muscle relaxants, opioids, and antidepressants, in comparison to their non-cannabis-using counterparts. This may also highlight that cannabis may have been sought as an alternative means of pain management, especially in situations where previous therapies yielded suboptimal results.
In this cohort, approximately two-thirds of cannabis non-users expressed interest in using cannabis for managing their chronic MSK pain, but often reported that they lacked knowledge regarding efficacy, access, usage, and composition. Interestingly, stigma was not a primary concern for cannabis non-users as previously cited in the literature (Bottorff et al. 2013; Hathaway et al. 2011; Satterlund et al. 2015), possibly attributed to the recent cultural shifts with cannabis legalization and with the increasing number of cannabis products that do not need to be smoked for consumption (only one third of products consumed in this study were smoked), leading to greater social acceptability and normalization (Hathaway et al. 2011). Research indicates that individuals are learning about cannabis from acquaintances and the internet instead of healthcare professionals (Corroon and Phillips 2018), which is consistent with the findings of the current study whereby only a quarter of patients started using cannabis as a result of a physician’s recommendation. Although the general perception is that cannabis is safe, there is a potential for side effects and drug interactions of which patients need to be aware (Alsherbiny and Li 2018; Iffland and Grotenhermen 2017). However, a lack of confidence regarding their knowledge on cannabis safety and efficacy exists among physicians (Fitzcharles et al. 2014; Kondrad and Reid 2013), which may prevent them from either initiating or participating in discussions regarding medical cannabis use with their patients. As such, continuing education initiatives targeting physicians are important to ensure they are armed with basic, albeit necessary, information regarding medical cannabis.
With the increased legalization of cannabis across North America and the clear interest by MSK pain patients to use cannabis therapeutically, there is large knowledge gap to fill in understanding the role of cannabis, if any, in managing chronic MSK pain. Future investigations should aim to conduct high-quality multicentre double-blind placebo-controlled trials with larger sample sizes and longer durations to assess the clinical efficacy and the long-term adverse events of cannabis as a monotherapy and in conjunction with standard analgesics. Future studies should aim to determine the optimal dosage, dose-response effects, drug interactions, and the ideal composition and route of administration based on patient history and preference.
Limitations
This study has several limitations. First, the survey utilized was not validated and the inability to compare characteristics of study participants with non-participants (i.e., those who declined or weren’t eligible) limits the capacity to assess the external validity of the research. Second, the prevalence of cannabis use may be understated, given the stigma often associated with cannabis use and the use of self-reported data. However, the anonymous nature of the survey may have minimized this concern. Third, recall bias may have occurred with cannabis-related information, possibly affecting data accuracy. Additionally, the higher prevalence of comorbidities among cannabis users compared to non-users, may potential influence results and perceptions. Fourth, the survey only assessed the frequency and mode of administration and did not account for the dosage and precise composition of THC and CBD within the cannabis products being consumed. Fifth, the study was conducted in an academic, urban setting and limited to patients referred for Orthopaedic consultation, which limits the generalizability of these results to the broader MSK pain population. Finally, data collection started weeks following legalization at a single time interval, therefore the patient’s patterns and perceptions of cannabis efficacy and safety may change with increased awareness, social acceptability, and/or cannabis education since the time of the survey. We aim to repeat this work in the coming years to assess changes in use over time and collect validated patient reported outcome measures between cannabis users and non-users with chronic MSK pain, which will aim to improve upon some of the limitations identified herein.
