Table 1

Overview of variables and measures used in the study of factors contributing to UK medical students’ mental ill-health symptoms

Variables	Measure/Study	Subscales	No. of items/ Scoring	Example item	Cronbach’s α	Diagnostic or recoding of the scale
Burnout	Maslach Burnout Inventory—General Survey for Students48	Emotional exhaustion	5 items, 0 (never) to 6 (every day)	I feel emotionally drained by my studies.	0.894	The scores for each subscale were categorised into tertiles, and the lower, middle and higher tertiles were labelled as ‘low’, ‘average’ or ‘high’, respectively.
		Cynicism	5 items, 0 (never) to 6 (every day)	I have become less interested in my studies since my enrolment.	0.839
		Professional accomplishment	6 items, 0 (never) to 6 (every day)	I have accomplished many worthwhile things in my studies.	0.811
Insomnia	The Insomnia Severity Index49	n/a	7 items, 0 (scores showing no insomnia) to 4 (showing severe insomnia)	How satisfied/dissatisfied are you with your current sleep pattern?	0.866	No signs of insomnia: 0–7 Subthreshold insomnia: 8–14 Clinical insomnia (moderate severity): 15–21 Clinical insomnia (severe insomnia): ≥22
Somatisation	The Somatic Symptom Scale-850	n/a	8 items, 0 (not at all) to 4 (very much)	During the past 7 days, how much have you been bothered by stomach or bowel problems?	0.770	No to minimal symptoms: 0–3 Low: 4–7 Medium: 8–11 High: 12–15 Very high: 16–32
Hazardous drinking	The Alcohol Use Disorders Identification Test--C51	n/a	3 items, 0 (never; 1 or 2) to 4 (daily or mostly daily; 10 or more)	How often do you have a drink containing alcohol?	0.780	Answering three to four or more drinks consumed containing alcohol on a typical day of drinking or consuming six or more drinks on one occasion were classified as drinking hazardously.
Drug use	Authors developed	n/a	1 item, 0 (no) and 1 (yes) and prefer not to tell	Have you taken any substances (drugs, not including alcohol) for recreational use in the last month?	n/a	n/a
Anxiety/Depression	The Patient Health Questionnaire-452	n/a	4 items, 0 (not at all) to 3 (nearly every day)	Over the last 2 weeks, how often have you been bothered by little interest or pleasure in doing things?	0.852	No symptoms: 0–2 Mild symptoms: 3–5 Moderate symptoms: 6–8 Severe symptoms: 9–12
Eating disorders	The Eating Disorder Diagnostic Scale53	Anorexia tendencies	18 items, a variety of question types: 4 questions: 0 (not at all) and 6 (extremely) 8 questions: 0 (no) and 1 (yes) 1 question: 1 (1 day) to 7 (7 days) 5 questions: 0 (0 times) to 14 (14 times)	Have you had a definite fear that you might gain weight or become fat?	n/a	Cut-off scores were calculated based on the procedure described by Stice et al, 53 except for using BMI and distinguishing from other eating disorders as measuring tendencies. Data on participants’ BMI were not collected as it was considered as sensitive and was left out of the calculations of scales.
		Bulimic tendencies		How many times per week on average over the past 3 months have you eaten an unusually large amount of food and experienced a loss of control?	n/a
		Binge-eating tendencies		During these episodes of overeating and loss of control, did you eat much more rapidly than normal?	n/a
Obsessive-compulsive disorder	Obsessive-Compulsive Inventory-Revised54	n/a	3 items, 0 (not at all) to 4 (extremely)	I find it difficult to control my own thoughts.	0.916	The scores were summed and if scores were ≥4, participants were classified as having obsessive-compulsive symptoms.
Personality disorder	The International Personality Disorder Examination55	Schizoid	9 items, 0 (false) and 1 (true)	I almost never get angry about anything.	n/a	For each subscale, if scores were ≥3 participants were classified as having a personality disorder symptom.
		Histrionic	6 items, 0 (false) and 1 (true)	I show my feelings for everyone to see.	n/a
		Antisocial (dissocial)	7 items, 0 (false) and 1 (true)	I will lie or con someone if it serves my purpose.	n/a
Paranoia	The Persecution and Deservedness Scale56	n/a	10 items, 0 (not at all) to 4 (certainly true)	There are times when I worry that others might be plotting against me.	0.883	The scores were averaged using the mean, and the formula mean+1 SD was used to classify participants with paranoia symptoms (above the cut-off) and no paranoia symptoms (below the cut-off).
Bipolar	Hypomanic Personality Scale57	n/a	6 items, 0 (false) and 1 (true)	There have often been times when I had such an excess of energy that I felt little need to sleep at night.	0.713	The scores were summed, and those participants scoring 6 points were classified as having bipolar symptoms.
Educational climate	The Educational Climate Inventory58	Centrality of learning and mutual respect	10 items, 0 (strongly disagree) to 3 (strongly agree)	I often get valuable and supportive advice from medical school teaching staff on how to improve.	0.890	n/a
Educational climate	The Educational Climate Inventory58	Competitiveness	6 items, 0 (strongly disagree) to 3 (strongly agree)	The atmosphere here is highly competitive.	0.765	Values are reversed, with higher scores representing a less competitive environment.
Belongingness: perceived peer support	Belongingness Full Scale59	n/a	6 items, 0 (completely true) to 4 (completely untrue)	I have developed personal relationships with other students in class/placements.	0.898	n/a
Help-seeking behaviour	General Help-Seeking Questionnaire60	n/a	16 items, 0 (extremely unlikely) to 6 (extremely likely)	If you were having mental health or emotional problems, how likely is it that you would seek help from your intimate partner?	0.868	n/a
Perceived stigma	Perceived Stigmatisation61	n/a	10 items, 1 (strongly disagree) to 4 (strongly agree)	It is a sign of personal weakness or inadequacy to receive treatment for emotional or mental health problems.	0.814	n/a
Observed stigma	Observed Stigmatising Experiences61	n/a	6 items, 0 (never) to 3 (4 or more times)	How many times have you observed your supervisors (eg, junior doctors, consultants/GPs, and medical school teaching staff) at your institution reveal students’ emotional problems to others?	n/a	A sum of one or more represents that stigmatising behaviour was observed.
The impact of the pandemic	Authors developed	Unpreparedness	2 items, 0 (strongly disagree) to 4 (strongly agree)	I feel I am behind on my learning due to the pandemic.	0.738	n/a
The impact of the pandemic	Authors developed	Unsupported	2 items, 0 (strongly disagree) to 4 (strongly agree)	My medical school/university provided an appropriate support to me to deal with the COVID-19-related challenges.	0.662	Values are reversed, with higher scores representing a less competitive environment.
Stressful life events	Stressful Life Events Questionnaire62	n/a	12 items, yes and no	Have you personally experienced assault within the prior year?	n/a	If a student did not experience any stressful events, it was coded as 0; if they experienced one or more stressful events, it was coded as 1.
Demographic characteristics	Self-developed items by the authors of this paper	n/a	9 items, a variety of question types (described in table 2)	Which of the following best describes your gender identity?	n/a	n/a

Cronbach’s α calculated for all baseline participants.
BMI, body mass index; COVID-19, coronavirus disease 2019; GP, general practitioner; n/a, not available.