Table 1 Summary of assessments

Primary Outcome

Assessment

Depressive symptoms

9-item Patient Health Questionnaire-9 (PHQ-9) [27]

Anxiety symptoms

7-item Generalised Anxiety Disorder scale (GAD-7) [32]

Anxiety concerning the COVID-19 pandemic

5-item Coronavirus Anxiety Scale (CAS) [33]

Non-specific psychological distress*

10-item Kessler-10 (K-10) [34]

Perceived social support

4-item (abbreviated) Medical Outcome Study Social Support Survey (MOS-SSS) [35]

Substance use

8-item Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) [36]

Sleep hygiene

7-item Insomnia Severity Index (ISI) [37]

Health-related quality of life

12-item Assessment of Quality of Life (AQoL 4D) [38]

Health service use

Self reported use of prescription and over the counter medications, health professional visits, hospitalisations, absenteeism and presenteeism over the past 8 weeks

Stool consistency

4-item (modified) Bristol Stool Form Scale (BSFS) [39]

Psychosis symptoms

7-item Early Psychosis Questionnaire [40]

Physical activity levels

5-item Simple Physical Activity Questionnaire (SIMPAQ) [41, 42] and a modified Borg scale [43]

IBS diagnosis

1-item self-developed question asks participants if they have been told they have irritable bowel syndrome (IBS) by a general practitioner or gastroenterologist

High-density lipoprotein, Lower-density

lipoprotein, total cholesterol

Fasting blood samples

Triglycerides, blood glucose

Fasting blood samples

Cardiovascular health

Systolic and diastolic blood pressure measured using an automatic sphygmomanometer

Waist circumference, hip circumference, height, weight

Height (to the nearest 0.1 cm), body weight (to the nearest 0.1 kg), waist circumference (to the nearest 0.1 cm) and hip circumference (to the nearest 0.1 cm)

Lower body muscular strength and upper body muscular strength

30-s sit-to-stand and 30-s bicep curl test

Diet intake

Dietary Questionnaire for Epidemiological Studies version 3.2 (DQES v3.2)—a modified version of the food frequency questionnaire developed by Cancer Council Victoria [44]

Gut microbiome composition

Stool collection (OMNIgene kits) [45]

Health-related social needs

15-item American Academy of Family Physicians’ Social Needs Screening Tool [46]

Medication adherence

8-item Morisky Medication Adherence Scale (MMAS) [47]

Perceived self-efficacy

6-item (abbreviated) General Self-Efficacy Scale (GSE) [48]

Readiness to make changes in behaviour prior to the intervention [49]

3-item Readiness to Change Questionnaire (RCQ)

Treatment expectancy and rationale credibility

6-item Credibility/Expectancy Questionnaire (CEQ) [50]

Prevalence of current and past major psychiatric disorder

Mini-International Neuropsychiatric Interview (MINI) [30]