Is Marijuana Really the Best Way to Treat Chronic Pain?

Surprising results from a new large-scale, multi-center study.

Posted Jul 05, 2018

One good thing about music, when it hits you, you feel no pain. —Bob Marley

Cannabis remains controversial as more states and countries legalize both medical and recreational use. Claims for the health benefits of cannabis are legion, including efficacy in the treatment of psychiatric conditions like depression and anxiety as well as addiction, anti-cancer and cognitive benefits, and relief of chronic pain. While there is some evidence of cannabis's efficacy in these and other conditions, studies are smaller-scale or based on animal or laboratory models, and they are inconclusive at best, misleading at worst. It’s difficult to sort out data from spin, given strong voices for cannabis advocacy and the human proclivity to both believe what we wish to be true and to selectively pay attention to and promote confirmatory information while ignoring and excluding evidence against what we want.

The hard reality of chronic pain

When it comes to chronic pain, there is a great need to develop safe and effective treatments as current treatments are not adequate.  According to the American Academy of Pain Medicine, 100 million Americans experience chronic pain conditions, not including an additional 55 million with pain from diabetes, cancer, heart disease and stroke. Chronic pain results in difficulty in daily function and is a cause of poor sleep for 20 percent of people. It is estimated to carry a yearly financial strain on the economy upwards of $550 billion. 

Opioid medications are challenging as a treatment for chronic pain, in part due to increasing tolerance with regular use—meaning that medication is less and less effective over time, and may require higher doses to get the same effect. Research indicates that chronic pain can reinforce the reward, with opioids potentially increasing the risk of addiction, especially when they are prescribed incorrectly (Volkow, 2018). Given the increasing abuse of prescription pain killers and the opioid epidemic, cannabis is an alluring alternative, if effective.

Other treatments, including non-opioid medications for pain and non-pharmacologic interventions (surgical, neurostimulation, therapy, etc.), are of limited use, leading people suffering from chronic pain to cope with often disabling and distressing symptoms for long periods of time. Given both the potential promise of as well as hype around cannabis, it makes perfect sense that many look to cannabis to alleviate intractable pain. But do standard cannabis preparations actually work for chronic, non-cancer-related, pain? Studies to date have not systematically addressed this question in a large population of people taking opioids for chronic pain.

The POINT study of cannabis in chronic pain

In a recently published study in Lancet Public Health, part of the larger POINT Study (Pain and Opioids IN Treatment), a team of researchers looked at whether cannabis provided effective pain relief for patients with chronic, non-cancer-related pain, whether there were significant associations with depression and anxiety, and whether cannabis use had an impact on the use of opioids.

They recruited 1,514 patients with chronic pain for a baseline assessment and followed them over four years, starting between 2012 and 2014. Although there were some drop-outs over the years, at each stage of the study approximately 80 percent of participants remained engaged, which is considered good for long-term studies like this one. Participants had to be 18 years or older, experiencing chronic pain (lasting more than three months) unrelated to cancer, taking prescribed opioid pain relievers for at least six weeks (e.g. fentanyl, morphine, oxycodone, buprenorphine, methadone and hydromorphone), and able to competently participate in the study.

Study participants were interviewed at baseline and three months later as part of the initial study assessment, and at follow-up intervals every year. Researchers examined 1) the use of cannabis use over the four year period; 2) the reasons for cannabis use and perceived efficacy; 3) correlations between reported cannabis use and pain, mental health and opioid pain-relief treatment; and 4) how effective cannabis was on pain severity and how much pain interfered with daily function.

The study included measures to assess characteristics of pain such as severity and duration, participant’s beliefs about their ability to function in spite of pain, whether the pain was neuropathic (burning or tingling indicated a neurological component), and whether participants experienced depression or anxiety or had a substance use disorder. Statistics were analyzed for associations over time and controlled for multiple variables (e.g. age, sex, clinical condition).

Main findings

The study group was 44 percent male, with an average age of 58 years. Nearly half were unemployed and 31 percent were retired. They reported experiencing chronic pain for an average of 10 years, with a range from 4.5 to 20 years. They were receiving an average morphine-equivalent dose of 75 mg per day. Participants often reported having two to three pain conditions, with a high number (62 percent) reporting neuropathic pain.

In terms of cannabis use, 40 percent reported ever using cannabis, 13 percent in the past year, and 9 percent in the past month. Use of cannabis increased significantly over the course of the study, perhaps reflecting increasing general acceptance of marijuana and reports of possible utility for pain (and other conditions). The number of people using less frequently did not change over the four years, but those with daily or nearly daily use more than doubled from 3 percent to 7 percent. The fraction of participants who did not have access to cannabis, who said that they would use cannabis if they could get it, doubled from 33 percent to 60 percent by the end of the study.

Those who reported using cannabis for pain indicated that, on a scale of 1 to 10 (with 10 being “extremely effective”), cannabis averaged a 6.5 rating. Participants who used cannabis reported that they did so to relieve pain, distress from pain, for poor sleep, and for general relaxation. Those who stopped said they did so because of side effects of cannabis, legal concerns, difficulty getting cannabis, and lack of effectiveness for relieving pain. Those who used cannabis both more frequently and less frequently reported doing so because of greater pain severity and pain interference, decreased pain self-efficacy, and higher levels of anxiety.

Did cannabis reduce opioid use in those who used cannabis for chronic pain? By the end of the study, 30 percent reported they had reduced their opioid dose as a result of using cannabis. However, the data told a different story than participants did. There actually were no differences in opioid use between those who reported reduced opioid use with cannabis and those who did not. So, participants believed that cannabis was allowing them to take less pain medication, when in reality (at least in this study sample), they were not. In addition, there were no other differences between those who perceived reduced opioid use with cannabis and those who did not, including no differences in age, sex, pain severity, or degree of pain interference with daily life.

There were no consistent differences in amount of opioid use or rate of discontinuing opioid medication between higher and lower cannabis consumption, except that at the end of the study, those who used cannabis infrequently were less likely to stop opioids (9 percent) than those who reported no cannabis use at all (21 percent), in spite of taking the same amount of pain medication.

Furthermore, greater cannabis use earlier in the study was not associated with a change in opioid use in the next year of the study, for any study year. Those who reported cannabis use in one year, in fact, had greater pain interference in daily living in the next year, suggesting that rather than assisting patients with chronic non-cancer-related pain, cannabis use was associated with greater perceived difficulty later on.

Implications

The findings of this large, multicenter, prospective, controlled naturalistic study may be surprising for those who consider cannabis to be an effective remedy for chronic pain and a potential medication for psychiatric conditions and opioid dependency. In this population, cannabis use did not predict reduced pain or disability from pain, decreased opioid use, or greater self-efficacy in the face of pain.

Although cannabis-consuming participants reported that they had reduced pain and less opioid medication use, pain assessment scales and medication tracking showed that participants’ reports were inaccurate: There were no significant differences in medication use and pain severity, or interference in daily life from pain, between those who took cannabis and those who did not.  We have to wonder why cannabis users perceive less pain and opioid use than non-users and whether there is any benefit to believing pain is relieved even when it is not. While optimistic distortions can be adaptive, allowing us to strive for better rather than pessimistically resign, the illusion that a drug is helping with a condition when it is not can get in the way of seeking effective treatment and obtaining real relief.  It is also hard to see benefit in believing one is taking less pain medication than one actually is; in fact, there are problems with underestimating the amount of medication one is taking both in terms of proper management of care as well as for risk of overuse.

Participants in this study obtained illicit cannabis and took it without medical oversight. It may be that certain medical preparations of cannabis (with consistent dosing, different ratios of THC and CBD, different delivery routes), prescribed in a clinical setting and within a therapeutic program may show efficacy for chronic pain, addiction and for other conditions.

However, the present study does not suggest that cannabis works for chronic pain. Rather than helping with actual pain, difficulty from pain, and need for opioid medication, cannabis consumption may lead people to believe they are improving when in reality they are not.

References

Campbell G, Hall WD, Peacock A, Lintzeris N, Bruno R, Larance B, Nielsen S, Mattick RP… (2018). Effect of cannabis use in people with chronic non-cancer pain prescribed opioids: findings from a 4-year prospective cohort study. Lancet Public Health, 3: e341-50.

Volkow N. (2018). Use and misuse of opioids in chronic pain. Annual Review of Medicine, January, Vol. 69, Issue 1, pp. 451-465.