Table 2 Study Measures

Mental health difficulties

Kessler Psychological Distress Scale – 10 (K10 [41]): 10 items assessing symptoms of depression and anxiety in last 4 weeks. Widely used in clinical trials for common mental health disorders, with well-established symptomatic and clinical cut-points, high specificity (0.96), and robust total classification accuracy (0.92) to identify mood and anxiety disorders [41].

Mental health disorders

The Mini International Neuropsychiatric Interview (MINI): Brief 15-min structured diagnostic interview for common DSM-5 psychiatric disorders, validated for telephone administration and use in clinical trials [42]. Depressive and anxiety disorders will be assessed.

Suicidal ideation

The Suicidal Ideation Attributes Scale (SIDAS [43]): 5-item screener for the presence and severity of suicidal thoughts in the last month based on frequency, controllability, closeness to attempt, level of distress, and impact on daily functioning. Any ideation is indicative of risk for suicidal behaviour; scores > 21 indicate high risk.

Specific mental health symptoms

Depression Anxiety Stress Scale −21 (DASS-21 [44]): 21 items assessing symptoms of depression, anxiety, and stress in the past week, with higher scores indicating greater symptom severity.

Social support

The Medical Outcomes Study-Social Support Survey (MSSS [45]): 14 items assessing perceived availability of tangible, emotional, affective and positive support.

Attitudes to help-seeking

The Barriers to Help Seeking Scale (BHSS [46]): 31 items assessing attitudinal barriers to help seeking for mental health/wellbeing problems.

Unmet need for health services

Adapted Perceived need for Care Questionnaire: Modified version of the Perceived Need for Care Questionnaire [47] asking if different forms of mental health care was need, but could not be accessed.

Parenting self-efficacy

Karitane Parenting Confidence Scale (KPCS [48]): 15 items assessing parents’ perceived parenting self-efficacy or sense of competence in their parenting abilities.

Parent-child relationships

Child-Parent Relationship Scale-Short Form (CPRS): 15 items assessing parents’ perceptions of their relationship with their child [49].

Stressful life events

Adapted Pregnancy Risk Assessment Monitoring System (PRAMS [50]): 25 items asking about stressful life events experienced in the last year.

Quality of life

The Assessment of Quality of Life 8 dimension (AQoL-8D [51]) is a validated tool assessing quality of life impacts in economic evaluation. The AQoL-8D is particularly suited to measuring mental health aspects of quality of life.

Health service use and health care costs

Study designed self-reported type, number and cost of healthcare services accessed, and examination of linked MBS/PBS data covering 24 weeks from baseline to follow-up.