<i>Background:</i> With expected increases in the number of older adults worldwide, the delivery of stepped psychological care for depression and anxiety in older populations may improve both treatment and allocative efficiency for individual patients and the health system.
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<i>Design:</i> A multisite pragmatic randomised controlled trial evaluating the clinical and cost-effectiveness of a stepped care model of care for treating depression and anxiety among older adults compared to treatment as usual (TAU) will be conducted. Eligible participants (<i>n</i> = 666) with clinically interfering anxiety and/or depression symptoms will be recruited from and treated within six Australian mental health services. The intervention group will complete a low intensity cognitive behavioural therapy (CBT) program: Internet-delivered or using a work-at-home book with brief therapist calls (STEP 1). Following STEP 1 a higher intensity face-to-face CBT (STEP 2) will then be offered if needed. Intention-to-treat analyses will be used to examine changes in primary outcomes (e.g. clinician-rated symptom severity changes) and secondary outcomes (e.g. self-reported symptoms severity, health related quality of life and service utilisation costs). An economic evaluation will be conducted using a cost-utility analysis to derive the incremental cost-effectiveness ratio for the stepped care intervention.
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<i>Discussion:</i> This study will demonstrate the relative clinical and economic benefits of stepped care model of psychological care for older adults experiencing anxiety and/or depression compared to TAU. The evaluation of the intervention within existing mental health services means that results will have significant implications for the translation of evidence-based interventions in older adult services across urban and rural settings.
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<i>Trail registration:</i> Prospectively registered on anzctr.org.au (ACTRN12619000219189) and isrctn.com (ISRCTN37503850).