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Largest UK study on medical cannabis prescriptions shows changes in patients’ quality of life

Published: 17/03/2023

Cannabis-based medical products (CBMPs) have been legally available for eligible patients through prescription in the UK since November 2018. They may be considered for various conditions in cases where conventional licensed medications have proven ineffective. The decision to prescribe must be made by a doctor who is on the General Medical Council’s Specialist Register. Indications for which medical cannabis may be considered include treatment-resistant epilepsy, chronic pain, multiple sclerosis, and post-traumatic stress disorder (PTSD).

In the UK, the vast majority of medical cannabis prescriptions are filled by private clinics while access via the NHS remains critically low. Furthermore, the National Institute of Health and Care Excellence (NICE) currently only recommends the use of CBMPs for intractable chemotherapy-induced nausea and vomiting, spasticity in adults with multiple sclerosis, and severe treatment-resistant epilepsy in Lennox-Gastaut and Dravet syndromes. This is due to a paucity of high-quality clinical evidence supporting the safety and efficacy of CBMPs in a clinical setting.

While this gap in clinical evidence persists, other forms of data collection – such as real-world, observational studies, may prove useful in improving our understanding of the potential of medical cannabis. To this end, in 2019, Sapphire Medical Clinics established the UK Medical Cannabis Registry (UKMCR) to collect data on safety and efficacy in patients prescribed CBMPs in the UK for various indications. A recent study analysed this data to assess the effects of medical cannabis on health-related quality of life (HRQoL) and the incidence of adverse events.

Design and Methods of the Study

This study assessed data collected from the UKMCR of patients prescribed CBMPs for any condition. Participating patients were prescribed individual medical cannabis preparations, such as oils, lozenges, and dried flower) according to the clinical requirements in joint decision-making between clinical and patients. Prescribed CBMPs contained either isolated cannabinoids (e.g., CBD or THC) or broad/full-spectrum extracts and dry flower.

Patient-reported outcome measures (PROMs) and adverse events were recorded at baseline and follow-up at 1 month, 3 months, 6 months and every 6 months thereafter. Changes in the use of other medications were recorded during medical cannabis treatment, including the use of opioid medications. Prescribed opioid medications were converted to oral morphine equivalents (OME) in accordance with recognized conversion factors stated by the British National Formulary.

Patient-Reported Outcome Measures (PROMs) and Adverse Events

Quality of Life PROMs were recorded using: EQ-5D-5L – the HRQoL measure recommended by NICE; Single-Item Sleep Quality Scale (SQS), Generalised Anxiety Disorder Assessment (GAD-7), and Patient Global Impression of Change (PGIC).

Participating patients were also prompted to report adverse events (AEs) prior to completing PROMs or during follow-up with a clinician. AEs were classified and graded using the Common Terminology Criteria for Adverse Events version 4.0.


Following the application of the exclusion criteria (not completing PROMs at baseline; treatment duration less than 1 month), a total of 2,833 patients were included in the current analysis. This included 2,314 patients who had completed PROMs at 1 month, followed by 1,598 at 3 months, 953 at 6 months, and 208 at 12 months.

In total, there were 31 different diagnoses recorded, the most common primary indications being chronic non-cancer pain (32.26%), anxiety (11.22%), fibromyalgia (10.80%), and neuropathic pain (8.37%). A secondary indication was reported in 1,116 (39.39%) participants, of which 420 (14.82%) also recorded a tertiary diagnosis. Anxiety and/or depression were reported in 1,406 (49.63%) patients.

Patient-reported outcome measures (PROMs)

Changes were seen in HRQoL at 1 month, 3 months, 6 months, and 12 months compared to baseline, as demonstrated by EQ-5D-5L index value, GAD-7, and SQS. Changes were also recorded separately in each subscale of EQ-5D-5L, including mobility, self-care, usual activities, pain or discomfort, and anxiety or depression, at 1 month, 3 months, and 6 months.

While changes in anxiety symptoms were reported across all participants treated with CBMPs, the GAD-7 score was still pathological at all follow-ups except after 12 months.

Adverse Events

Across the study period, a total of 5,176 AEs were reported by 474 (16.73%) patients. The mean number of AEs per reporting patient was 1.83 ± 6.82. The majority of AEs were categorised as mild (n= 2,201; 77.69%) or moderate n= 2,239; 79.03%), compared to severe (n = 730; 25.77%), and life-threatening/disabling (n = 6; 0.21%). The most commonly reported AEs were fatigue (n = 409; 14.42%) and dry mouth (n = 347; 12.25%), followed by somnolence (n = 312; 11.01%), lethargy (n = 308; 10.87%), insomnia (n = 299; 10.55%), headache (n = 297; 10.48%), concentration impairment (n = 286; 10.10%), nausea (n = 242; 8.54%), and dizziness (n = 228; 8.05%).

The data also indicated that cannabis consumption prior to baseline (current user, ex-user) was a protective factor. On the other hand, female patients and cannabis-naïve patients appeared to be at increased risk of experiencing adverse events.


The data assessed in this observational study indicates that medical cannabis treatment is associated with changes in HRQoL, and sleep- and anxiety-specific symptoms in patients with chronic illness.

The researchers conclude that the findings of this study “may help to inform current clinical practice, but most importantly, highlight the need for further clinical trials to determine causality and generate guidelines to optimise therapy with CBMPs.”

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