Major Depressive Disorder in adolescence is prevalent and debilitating. Our group aims to improve treatment response through the use of an Integrated Care Pathway (ICP) based on a high quality Clinical Practice Guideline and measurement-based care (MBC; where periodic symptom scale scores are used to make treatment decisions). We propose a controlled clinical trial comparing ICP to treatment-as-usual (TAU) across two sites.

Background: There is a gap between what is known from the evidence about the treatment of adolescent depression and what is practiced. Moreover, while there is evidence that measurement-based care can improve outcomes for adults with various mental health conditions, there is limited information on this framework in adolescent depression.

Objective: Our study aims to enhance the implementation of evidence-based care (using the NICE Clinical Practice Guidelines as a template) combined wtih measurement-based care through the use of an Integrated Care Pathway (ICP) in adolescents with depression.

Hypothesis: As this is a pilot study, our hypotheses centre around feasibility. We hypothesize that: (1) we will recruit at least 30 participants to the ICP treatment arm and 30 participants at the "treatment-as-usual" arm at a different site (2) that baseline measures will be fully completed by 95% of adolescents recruited, (3) that baseline measures will take 2 hours to complete for adolescents and 1 hour to complete for caregivers, (4) that a mean of 90% of the key aspects of the treatment protocol are followed in the ICP group (5) that 80% of participants recruited will complete measures at the end of the 20-week interval and that (6) 90% of the youth, caregivers and clinicians who partake int eh study will attend a focus group to provide qualitative feedback on their experience.

Design: This is a non-randomized controlled clinical trial. Randomizing at the individual level is not possible - the intervention is implemented at the clinic level; so the effect of the intervention on one youth within a clinic would influence the care of other youth at the clinic.

Sampling: Participants are recruited from psychiatric clinics at 2 sites. Each site will recruit to their respective treatment arm.

Inclusion Criteria:

• Psychiatrist's impression is that depression is a primary psychiatric. concern
• 14-18 years old.
• DSM-5 criteria for Major Depressive Disorder or Persistent Depressive Disorder as per the Diagnostic Interview for Affective Symptoms for Children (DIAS-C19).
• Speak, read and write English at a grade 6 level.

Exclusion Criteria:

• Threshold psychotic symptoms.
• Bipolar disorder.
• Moderate-to-severe substance use disorder.
• Autistic spectrum disorder or intellectual disability.
• Eating disorder.
• Suicide-related behaviours requiring acute intervention.

Participants are not blinded.