In recent years, cannabis use has been on the rise among patients with a wide range of conditions. Improved access to medical cannabis and ongoing liberalisation of recreational markets, in addition to increased clinical research into the clinical use of the plant and its derivatives appear to have contributed to this rise. However, the true prevalence of cannabis use among patients – including those with multiple sclerosis (MS) – remains difficult to predict.
The authors of a recent paper proposed a retrospective study via the 2011-2020 National (Nationwide) Inpatient Sample (NIS) from the United States to gain insight into the growing use of cannabis among adult MS patients with chronic pain in the USA.
What is Multiple Sclerosis?
Multiple Sclerosis is a disease that affects the central nervous system, affecting the flow of information both within the brain and between the brain and the rest of the body. It occurs when the immune system begins to attack the central nervous system; however, the reason for this abnormal function is unknown. The damage caused to myelin – the insulating layer that forms around nerves – disrupts signals to and from the brain. In turn, this can cause several unpredictable symptoms, including numbness, pain, fatigue, mood changes, memory problems, blindness, and even paralysis.
There is currently no cure for MS. Instead, current treatment options focus on controlling the condition and easing the symptoms. The treatments used depend on the stage of the disease and the specific symptoms experienced by the patients. However, this often includes steroids to treat relapses of MS symptoms, medicines such as duloxetine, gabapentin, or amitriptyline to manage pain, and other medicines combined with physiotherapy to manage muscle spasms and stiffness.
Medical Cannabis and Multiple Sclerosis
In a growing number of US states and other jurisdictions around the world, patients with MS are able to access cannabis-based medicines. In the UK, the National Institute for Health and Care Excellence (NICE) recommends that clinicians offer a 4-week trial of a licensed THC:CBD spray (nabiximols) to treat moderate to severe spasticity in adults with multiple sclerosis of other pharmacological treatments are not effective.
There is growing evidence evaluating the potential of cannabis-based medicines, including nabiximols, for people with MS
Methods of the Study
The authors of the current study assessed data from the 2011-2020 NIS – the largest publicly available payer inpatient healthcare database designed to produce US regional and national estimates of inpatient utilisation, access, cost, quality, and outcomes. Via the use of ICD-9 and ICD-10 codes, the researchers identified adult cases of MS with a diagnosis of chronic pain. The trend in the prevalence of cannabis use among these patients was estimated between 2011 and 2020.
Results of the Study
In total, the researchers identified 135,447 admissions of MS patients with chronic pain. Across the studied period, 4,361 patients (3.22%) used cannabis. The prevalence of cannabis use per year among identified MS patients with chronic pain increased from 1.55% in 2011 to 4.04% in 2017. Between 2017 and 2020, the prevalence decreased to 3.30%. The mean age of patients using cannabis in this period fluctuated, from 43.31 years in 2011 with a gradual rise to 48.21 years in 2020.
The results of this study are in line with previous findings and hypotheses that indicate a rising prevalence of cannabis use among patients with multiple sclerosis. The authors note that, in the case of patients in the US, this is likely due to the expansion medical cannabis programs and legal recreational use in many states, in addition to decreasing stigma in patients reporting cannabis use.
The figures highlighted in this study provide the most recent and broad estimate of cannabis use among MS patients with chronic pain. The authors conclude with a recommendation for the initiation of further studies to understand the mechanism of action of medical cannabis when used in individuals with chronic pain.