Patients with inflammatory arthritis who were prescribed cannabis-based medicinal products (CBMPs) reported sustained improvements in pain, sleep and quality of life over two years, according to a new study using data from the UK Medical Cannabis Registry.
The research, published this month in Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders, analysed 192 patients prescribed CBMPs for inflammatory arthritis-associated chronic pain.
Participants completed questionnaires before starting treatment and after one, three, six, 12, 18 and 24 months. The measures covered pain severity, the effect of pain on day-to-day life, sleep, anxiety and health-related quality of life.
Improvements were seen across all pain measures at every follow-up point, as well as in sleep and overall health-related quality of life.
After two years, 62.5% of patients experienced what researchers considered a clinically meaningful improvement in pain severity, while 54.7% reported a meaningful reduction in how much pain interfered with their everyday lives. Just under half (49.5%) recorded clinically meaningful improvements using two other measures of pain.
Sleep also improved throughout the two years, with 45.3% of participants recording a clinically significant improvement by the end of the study. Anxiety scores improved significantly during the first three months of treatment. Although average scores remained below baseline at six, 12 and 24 months, these later differences were not statistically significant.
Inflammatory arthritis is an umbrella term covering several conditions in which inflammation affects the joints and other parts of the body. These include rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis.
Unlike osteoarthritis, which is primarily associated with changes to cartilage and other joint tissues over time, inflammatory forms of arthritis involve an abnormal immune response. Symptoms can include persistent joint pain, swelling, stiffness and fatigue.
Managing chronic pain remains an important part of treatment for many patients, and the researchers say clinical evidence supporting the use of cannabis-based medicines for inflammatory arthritis remains limited.
Of the 192 people included in the new study, 69 were taking prescription opioids when they began medical cannabis treatment. More than half of the participants were already cannabis consumers before entering the registry, while around 29% had never previously used cannabis.
Twenty-seven patients, around 14% of the study group, reported a total of 296 adverse events during the study. Of these, around 43% were classified as mild, 45% as moderate and 13% as severe. No life-threatening adverse events were reported.
The findings build on an earlier analysis of 82 patients from the UK Medical Cannabis Registry, which found improvements in pain, anxiety, sleep and quality of life during the first 12 months of treatment. The new study uses a larger group and extends the follow-up period to two years.
However, the researchers stress that the findings do not demonstrate that medical cannabis caused the improvements.
The study was observational, meaning there was no control group receiving another treatment or placebo for comparison. Patients were also reporting their own symptoms, and more than half were already using cannabis when they entered the registry.
The authors say the results instead provide further evidence to support randomised controlled trials examining whether cannabis-based medicines are an effective treatment for pain associated with inflammatory arthritis.
