StratCare Trial 2: Evaluating the Clinical and Cost-effectiveness of AI-driven Stratified Care for Depression

Depression and anxiety are common mental health problems affecting around one in six adults. Treatments include therapy, telephone or group-based activities delivered by therapists. Treatment uses a "stepped care" model where most patients start with very brief treatments. If they remain unwell after this, they access longer and more intensive therapy. This model does not always work, as only one out of two patients fully recover. The researchers have developed an artificial intelligence tool called "StratCare". It is designed to help health services to offer the best available treatment for each patient. StratCare is a computerised system that guides therapists on how to assess new patients. It asks a few questions about their symptoms, personality, and background. The system makes a recommendation about which treatment might be most effective for that person. This is either starting with brief therapy or starting with intensive therapy. The treatments are already used with depression in the National health Service (NHS). The patient can discuss with their therapist and decide whether to accept the recommendation. Otherwise, they can discuss trying other options. Previous research found that StratCare can help more people to recover from depression compared to the usual stepped care model. The researchers will investigate if the StratCare tool works on a large scale in the NHS and if it helps patients in the long-term. The researchers will run a trial involving 1252 participants using NHS Talking Therapies services. Half will use the StratCare tool to make a treatment recommendation. The other half will follow the stepped care approach. The researchers will contact participants in the trial after 6, 12 and 18 months to see if their mood and quality of life has improved. The researchers will also interview therapists and participants to see what they think about treatment being guided by the StratCare tool. Hypotheses: * Stratified care will result in lower mean depression scores compared to usual stepped care (USC). * Stratified care will result in a statistically significant higher proportion of cases with reliable and clinically significant improvement in depression symptoms, compared to USC. Primary Outcome: Depressive symptoms, as measured by change on the Patient Health Questionnaire (PHQ-9), at 12 months post-enrolment.