A Brief Psychological Intervention for Carer Fear of Cancer Progression

Treatment dropout is defined as attending fewer than two of the three sessions and not completing the post-intervention (Time 2) questionnaire. Feasibility will be indicated by a dropout rate of <30%.

Consent rate among eligible caregivers screened for participation will be evaluated. Feasibility will be indicated by a consent rate > 50%.

The number of included participants will be recorded. Feasibility will be indicated by the recruitment of 14 caregivers within the defined study period.

Participant-reported fear of cancer progression will be assessed in the beginning of each session using the Fear of Cancer Recurrence Inventory Short Form (FCRI-SF), adapted to measure fear of cancer progression in caregivers of patients with cancer. The FCRI-SF is a 9-item measure rated on a scale from 0 to 4, with total scores ranging from 0 to 45. Higher scores indicate greater fear of cancer progression.

Feasibility will be indicated by stability or decrease throughout the defined time frame.

Therapist adherence to key intervention principles (i.e., delivery of core therapeutic elements as intended) will be rated on a 0-2 scale. A random sample of 20% of sessions will be independently rated based on video recordings.

Participant-reported treatment satisfaction will be assessed using the 8-item Client Satisfaction Questionnaire (CSQ). Items are rated on a scale from 1 to 4, with total scores ranging from 8 to 32. Higher scores indicate greater treatment satisfaction.

Acceptability will be indicated by a mean sum score of ≥20.

Participant-reported negative effects will be assessed using the 20-item Negative Effects Questionnaire (NEQ).

First, respondents indicate whether each negative effect occurred during treatment using a yes/no format. Second, they rate the severity of each endorsed negative effect on a scale from 0 to 4, with higher scores indicating greater severity. Third, respondents attribute each negative effect either to "the treatment I received" or to "other circumstances".

Acceptability will be indicated by an absence of serious adverse events attributed to the intervention.

Participant-reported anxiety will be assessed using the 7-item anxiety subscale of the Hospital Anxiety and Depression Scale (HADS). Items are rated on a scale from 0 to 3, with total scores ranging from 0 to 28. Higher scores indicate greater anxiety.

Participant-reported cancer-specific distress will be assessed using the 22-item Impact of Events Scale Revised (IES-R). Items are rated on a scale from 0 to 4, with total scores ranging from 0 to 88. Higher scores indicate greater distress.

Participant-reported well-being will be assessed using the 5-item World Health Organization-Five Well-Being Index (WHO-5). Items are rated on a scale from 0 to 5, with total scores ranging from 0 to 100. Higher scores indicate greater well-being.

Participant-reported caregiver reaction will be assessed using the 24-item Caregiver Reaction Assessment (CRA). Items are rated on a scale from 1 to 5. The CRA comprises five subscales: Self Esteem, Lack of Family Support, Impact on Finances, Impact on Schedule, Impact on Health.

For the Self Esteem subscale, higher scores indicate greater esteem (positive outcome). For the remaining four subscales, higher scores indicate greater caregiver burden (negative outcome).

Subscale scores are calculated as mean item scores ranging from 1.0 to 5.0.

Participant-reported sleep health will be assessed using the 6-item RU SATED.

RU-SATED stands for:

Satisfaction: Are you satisfied with your sleep? Alertness: Do you stay awake all day without dozing? Timing: Are you asleep (or trying to sleep) between 2 am and 4 am? Efficiency: Do you spend less than 30 minutes awake at night (including time to fall asleep and awakenings)? Duration: Do you sleep between 6 and 8 hours per day?

Items are rated on a scale from 0 to 4, with total scores ranging from 0 to 24. Higher scores represent greater sleep health.

Participant-reported decentering from thoughts will be assessed using the 11-item decentering subscale of the Experience Questionnaire (EQ). Items are rated on a scale from 1 to 5, with total scores ranging from 11 to 55. Higher scores indicate greater levels of decentering.

Participant-reported valued living will be assessed using the 10-item Valuing Questionnaire (VQ). Items are rated on a scale from 0 to 6. The measure yields two subscales, Progress and Obstruction, each with total scores ranging from 0 to 30. For the Progress subscale, higher scores indicate closer alignment between one's values and actions (positive outcome). For the Obstruction subscale, higher scores indicate greater interference with living consistently with one's values (negative outcome).

Participant-reported worry will be assessed using the 16-item Penn State Worry Questionnaire (PSWQ). Items are rated on a scale from 1 to 5, with total scores ranging from 16 to 80. Higher scores indicate greater worry.

Participant-reported metacognitions will be assessed using the 30-item Metacognitions Questionnaire (MCQ-30). Items are rated on a scale from 1 to 5, with total scores ranging from 30 to 120. Higher scores indicate greater levels of unhelpful metacognitions.

Participant-reported treatment expectancy will be assessed using the 6-item Credibility/Expectancy Questionnaire (CEQ). Items are rated on a scale from 1 to 9. The measure yields two subscales, Credibility and Outcome Expectation, with total scores for each subscale ranging from 3 to 27. Higher scores indicate greater perceived credibility and outcome expectancy.

Participant-reported fear of cancer progression will be assessed in the beginning of each session using the Fear of Cancer Recurrence Inventory Short Form (FCRI-SF), adapted to measure fear of cancer progression in caregivers of patients with cancer. The FCRI-SF is a 9-item measure rated on a scale from 0 to 4, with total scores ranging from 0 to 45. Higher scores indicate greater fear of cancer progression.

Participant-reported metacognitions will be assessed in the beginning of each session using the 30-item Metacognitions Questionnaire (MCQ-30). Items are rated on a scale from 1 to 5, with total scores ranging from 30 to 120. Higher scores indicate greater levels of unhelpful metacognitions.

Participant-reported distance from thoughts will be assessed in the beginning of each session using the 11-item decentering subscale of the Experience Questionnaire (EQ). Items are rated on a scale from 1 to 5, with total scores ranging from 11 to 55. Higher scores indicate greater levels of decentering.

Participant-reported treatment understanding and everyday application will be assessed using six custom items. Four items are rated on a scale ranging from 1 (not at all) to 5 (to a high degree) and assess the extent to which participants (1) understood Detached Mindfulness (DM), (2) felt self-efficacious in applying DM in everyday life, (3) found DM helpful, and (4) applied DM in everyday life. The remaining two items are open-ended questions asking participants (1) to describe how they would explain DM to a friend and (2) to describe how and when they apply DM in everyday life.