Headache disorders are among the most common conditions affecting the nervous system and are a major cause of disability globally. They are characterised by recurrent headaches that can significantly affect health-related quality of life. Figures suggest that headache conditions, including migraine, have a global prevalence of around 50%, with the number of people reporting headache on 15 or more days every month being between 1.7% and 4% of the global adult population.
While headaches are the primary symptom of headache conditions, patients also commonly experience nausea, vomiting, photophobia, and phonophobia. Data from the Global Burden of Disease Study showed that in 2013 migraine alone was the sixth highest cause of years lost to disability, with headache disorders collectively being third. As a result, headaches represent a considerable burden on health services and are responsible for a high economic impact.
Current Treatment Options for Headache Disorders
A number of treatment options may be considered for migraine, including a combination of acute and preventative pharmacological therapies. Acute therapies may include non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol, and triptans while repurposed medications such as beta-blockers, tricyclic antidepressants, and anticonvulsants may be considered as additional preventative therapies.
The effectiveness of these therapies, however, is unpredictable with only around a third of patients experiencing an improvement in their symptoms. Furthermore, such treatment options are often associated with significant side effects, including fatigue, dizziness, weight gain, rashes and constipation. The frequent need for pain relief associated with headache conditions can also lead to the development of medication overuse headache (MOH), resulting in a cycle of headache symptoms.
More recently, more effective methods for the treatment of migraine have been introduced. Namely, onabotulinumtoxin A injections, and monoclonal antibodies targeting calcitonin gene-related peptide (CGRP) or its receptor; however, these therapies are expensive and access is limited. Therefore, there remains a significant need for the development of further therapies for migraine and other headache disorders.
A recent study analysed data from the UK Medical Cannabis Registry to determine current outcomes for patients with primary headache disorders.
Data Collection for the UK Medical Cannabis Registry
The UK Medical Cannabis Registry (UKMCR), which was set up by Sapphire Medical Clinics in 2019, is the first UK patient registry to collect data regarding CBMP prescription formulations, patient demographics, patient-reported outcome measures (PROMs) and adverse events (AEs).
Patient-Reported Outcome Measures (PROMs)
The data assessed in this study were reported electronically by patients or contemporaneously by clinicians during initial clinical consultations. Primary outcome measures were changes in PROMs from baseline to 1-, 3-, and 6-month follow-up. Secondary outcomes were the incidence and severity of AEs. PROMs were measured using the 6-item headache impact test (HIT-6), migraine disability assessment score (MIDAS), General Anxiety Disorder 7 (GAD-7), EQ-5D-5L, Single-Item Sleep Quality Scale (SQS), and Patient Global Impression of Change (PGIC).
The EQ-5D-5L is the HRQoL measure recommended by the National Institute for Health and Care Excellence (NICE). The SQS utilises a numerical rating scale rating from 0 (terrible) to 10 (excellent) to assess sleep quality over the past 7 days. GAD-7 evaluates seven aspects of generalized anxiety by the number of days they were experienced in the past fortnight. The PGIC assesses perceived change since starting treatment in terms of activity limitations, symptoms, emotions, and overall quality of life, through two parts.
Results of the Analysis
After exclusion, a total of 97 patients with a primary diagnosis of headache disorder were included in the final analysis. Of these, PROMs had been recorded for 81 patients at 1 month, 63 patients at 3 months, and 35 patients at 6 months. Most patients had a primary indication of migraine (n = 82; 84.5%), followed by cluster headache (n = 9; 9.3%), and tension-type headache (n = 6; 6.2%). Anxiety was the most common secondary indication (n = 16; 16.5%), followed by insomnia and chronic pain (n = 7; 7.2%), and depression (n = 4; 4.1%).
Headache and Migraine Severity
This analysis identified a statistically significant change in both HIT-6 and MIDAS scores at follow-up points compared to baseline: A majority of patients (61.3%; n =46/75) reported a >2.5-point change in HIT-6 scores at 1 month, compared with 71.7% (n = 43/60), and 66.7% (n = 22/33) of patients at 3-months and 6-months, respectively; the proportion of patients who had >5.0-point change in MIDAS scores was 57.3% (n = 43/75), 66.7% (n = 40/60), and 63.6% (n = 21/33) at 1-, 3-, and 6-months, respectively.
Health-Related Quality of Life (HRQoL)
Median GAD-7 and EQ-5D-5L scores significantly changed at 1- and 3 months follow-ups. However, due to extensive loss to follow-up, these findings should be interpreted with caution.
A total of 113 adverse events were experienced by 17 patients (17.5%). The majority of these AEs were classified as mild (n =63; 64.9%) with the most common being dry mouth (n = 11; 11.3%), headache (n = 11; 11.3%), fatigue (n = 8; 8.2%), and concentration impairment (n = 8; 8.2%).
The researchers note that the associated changes in headache- and migraine-specific PROMs reached clinically important thresholds. Nonetheless, the authors suggest that future research in this area focuses on randomised controlled trials (RCTs) to establish causality and to further assess CBMP safety and efficacy for headache disorders.