A 15-item scale assessing symptoms of anxiety and depression. It includes items from the Patient Health Questionnaire Scale (PHQ-8) for depression and the Generalised Anxiety Disorder Scale (GAD-7) for anxiety, each scored on a 4-point Likert scale from 'not at all' (0) to 'nearly every day' (3). Total scores range from 0 to 45 with higher scores indicating greater symptom severity.

8-item questionnaire scoring the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for depression on 4-point Likert scales from 'not at all' (0) to 'nearly every day' (3). Total scores below 5, 10, 15, 20, and up to 24 are categorised as none-to-minimal, mild, moderate, moderately severe, and severe depression.

A 7-item questionnaire assessing the severity of generalised anxiety symptoms based on DSM-IV criteria. Each item is scored on a 4-point Likert scale from 'not at all' (0) to 'nearly every day' (3). Total scores range from 0 to 21, with cut-off points at 5, 10, and 15, indicating mild, moderate, and severe anxiety, respectively.

A 14-item scale assessing how a long-term physical health condition has affected the psychological distress experienced by an individual over the last two weeks. Intrapersonal IRD = items 1-7 (cut-off = 15); Interpersonal IRD = items 8-14 (cut-off = 12).

The scale is augmented by 3 additional items. Two horizontal visual analogue scales ranging from 0 to 10: One indicating the amount of psychological distress that is attributed to having one or more physical Long Term Condition (LTC) over the last two weeks; one indicating the severity of psychological distress related to the LTC over the last two weeks. The final item asks the respondent to specify which LTC they are attributing their psychological distress to (as many people are affected by multiple LTCs in parallel).

A 5-item scale measuring the impact of mental health issues on daily functioning across work, home management, social leisure, private leisure, and close relationships. Each item is scored from 0 (no impairment) to 8 (severe impairment). Total score ranges from 0 to 40, with higher scores indicating greater functional impairment.

A 5-item scale measuring health-related quality of life across five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is rated on three levels (1 to 3). Total score ranges from 5 to 15, with higher scores indicating more severe issues in health-related quality of life.

A 6-item questionnaire assessing patient enablement (i.e. patients' ability to understand and cope with their health and illness) on a 4-point scale (much better, better, same or less, not applicable). Total scores range from 0 to 12, with higher scores indicating greater patient enablement.

A one-item questionnaire assessing perceived severity of participants' long-term physical conditions using a 4-point scale with scoring ranges from 0 to 3. Higher scores indicate greater severity.

A one-item questionnaire assessing how patient's health condition has changed since the beginning of the study on a 7-point scale with scoring ranges from 0 to 6. Higher scores indicate greater deterioration.

Usage of health services will be captured with the Health Service Use Questionnaire. Participants will indicate whether they have accessed key services, including general practitioner (GP), psychological or counselling services, and emergency care during the past 3 months. For each service reported, additional items capture (i) the number of contacts, (ii) the mode of contact (e.g., in-person, telephone, video), and (iii) the duration of the most recent contact.

Participants will also be asked about their access of charity resources. A multiple-selection drop-down box will show the following options (charity helpline, online forums/networks/phone counselling, information booklets, others)