Feasibility of Cannabidiol for the Treatment of Long COVID

Assessed by the COVID-19 Yorkshire Rehabilitation Scale (C19-YRS, Sivan et al., 2021). This scale includes: breathlessness, cough/ voice, swallowing/ nutrition, fatigue, continence, cognition, pain/discomfort, anxiety, depression, post-traumatic stress disorder, communication, mobility, personal care, activities of daily living, social role, perceived health status and family/carers views. The C19-YRS provides an overview of 3 outcomes: symptoms severity score, functional disability score and global health score.

Fatigue will be assessed using the nine item Fatigue Severity Scale (Krupp et al., 1989). This scale, which was initially designed for use in multiple sclerosis and systemic lupus erythematosus has been used extensively across multiple disorders and has bene demonstrated to have good reliability and validity. Each of the nine items in this scale is assessed on a seven-point scale from 1 (strongly disagree) to 7 (strongly agree). Thus, the composite scale ranges from 9 to 63 with higher ratings representing more severe fatigue.

The health-related quality of life instrument that will be used in this study is the EuroQol 5 Dimensions (EQ-5D; Devlin et al., 2017). It is a widely used, validated, and reliable tool that assesses the quality of life of patients in many disease areas through assessment of the severity of each of 5 dimensions (mobility, self-care, usual activities, pain/discomfort and anxiety/depression). Each dimension has 5 levels (1-5): no problems, slight problems, moderate problems, severe problems and extreme problems. The digits for the five dimensions can be numerically summed into a single number, varying from 5 to 25 with higher numbers representing a lower quality of life. In addition, this measure contains a 100-point visual analogue which asks respondents to rate their current health with higher numbers representing better health.

The Brief Pain Inventory Short Form (BPI-SF; Cleeland, 1989; Cleeland \& Ryan, 1994), a 9 item self-administered questionnaire, will be used to evaluate the severity of a patient's pain and the interference of this pain on the patient's daily feeling and functioning. The patient rates their worst, least, average, and current pain intensity, list current treatments and their perceived effectiveness, and rate the degree that pain interferes with general activity, mood, walking ability, normal work, relations with other persons, sleep, and enjoyment of life on a 10-point scale. The BPI scale defines pain as follows: 1-4=Mild Pain, 5-6=Moderate Pain, 7-10=Severe Pain. Thus, a mean of the items can be presented with higher ratings representing more severe pain. In addition, the mean of the 7 items assessing interference, each rated on a scale from 0 to 10, will be used as a measure of mean pain interference with higher numbers representing more interference.

The Generalised Anxiety Disorder Assessment (GAD-7; Spitzer et al., 2006) will be used to measure depression. The GAD-7 is a seven-item instrument that is used to measure or assess the severity of generalised anxiety disorder (GAD). Each item asks the individual to rate the severity of their symptoms over the past two weeks. Response options include "not at all", "several days", "more than half the days" and "nearly every day". The GAD-7 score is calculated by assigning scores of 0, 1, 2, and 3, to the response categories of "not at all," "several days," "more than half the days," and "nearly every day," respectively, and then adding together the scores for the seven questions. GAD-7 total score for the seven items ranges from 0 to 21.

The Patient Health Questionnaire (PHQ-9; Kroneke et al., 2001) will be used to measure mood/ depression. It is a reliable and valid measure of depression severity and is comprised of a 9-item self-rated instrument that has been validated in general populations, medical populations and psychiatric samples.

It is calculated by assigning scores of 0, 1, 2, and 3, to the response categories of not at all, several days, more than half the days, and nearly every day, respectively. PHQ-9 total score for the nine items ranges from 0 to 27.

Assessed using Pittsburgh self-report questionnaires and wearable technology. The Pittsburgh Sleep Quality Index (PSQI) includes a scoring key for calculating a patient's seven subscores, each of which can range from 0 to 3. The subscores are tallied, yielding a "global" score that can range from 0 to 21. A global score of 5 or more indicates poor sleep quality; the higher the score, the worse the quality. Mean ratings on this global score will be used in our analyses. Furthermore, the wearable technology (i.e. Fitbit) will provide the patients' total time in sleep and time in sleep stages (light, deep and REM sleep), as well as a daily Sleep Score accessed via the Fitbit app. Seven day averages (means) of the Fitbit measures will be calculated for each participant across the duration of the study.

The wearable technology will provide 24/7 heart rate tracking and heart rate variability. We will have access to the daily resting heart rate and averages across discrete periods. We will analyse mean resting heart rate (beats per minute). Variation in the time between each heartbeat (heart rate variability) will be accessed via the Fitbit app. Seven day averages (means) of the Fitbit measures will be calculated for each participant across the duration of the study.

Activity levels assessed via wearable technology. The wearable technology (i.e. Fitbit) tracks all-day activity including number of steps walked, distance walked (expressed in kilometres), floors climbed, active minutes and calories burned. We will analyse the seven-day mean number of daily steps, distance walked, stairs climbed, active minutes and calories burned. Seven day averages (means) of the Fitbit measures will be calculated for each participant across the duration of the study.

Oxygen saturation expressed as percentage saturation, with typical numbers being in the region of 95% will also be assessed via the Fitbit. Seven day averages (means) of the Fitbit measures will be calculated for each participant across the duration of the study.

Assessed using daily reports of key symptoms (breathlessness, fatigue, mood and pain) adapted from the COVID-19 Yorkshire Rehabilitation Scale. Each symptom will be scored out of 10 for a period of 7 days per 28 days, to produce an average score for each symptom.