Table 1.

Formative data sources and findings.

Source/Purpose	Key findings
Intervention design workshops: To align intervention design parameters with key theoretical principles, recent empirical evidence and national/international best practice; and refine formative research questions and methods	•Wide age range and multiple referral routes can maximise coverage, impact and buy-in from schools •Delivery in schools can reduce external structural barriers to accessing psychological interventions, but other constraints may be faced due to daily timetable (e.g., 40-min class periods), vacations and exam periods •Challenges of implementing systematic mental health screening in schools require brief, ecologically valid assessment tools, focused on symptom-based/functional dimensions rather than discrete diagnostic categories •Transdiagnostic ‘elements-based’ intervention design may have particular utility in designing parsimonious treatment packages in low-resource contexts •Public health impact may be strengthened through a stepped care approach that delivers a low-intensity intervention across diverse presentations, followed by a high-intensity treatment for non-responders that is tailored to specific problem profiles (e.g., by selecting/sequencing discrete treatment modules) •A relatively brief psychological intervention, focused on ‘here and now’ strategies, may be favoured by adolescents and is consistent with the requirements of a low-intensity first-line intervention •Simplified decision rules are needed to facilitate delivery by non-specialists •Digital delivery platforms and parental involvement should be explored further
Scoping literature reviews: To align intervention design parameters and decisions with the global evidence base	•Emerging support for transdiagnostic mechanisms in onset, maintenance and treatment of common mental health problems •Substantial support for stress-coping principles and their applications in cognitive and behavioural therapies, including self-help approaches •Self-help is most effective when provided with guidance, which may be delivered in various formats •Adolescents' may prefer practical coping strategies that fit with developmental drive for self-determination •Stepped care models, linked to measurement feedback systems, can maximise effectiveness and efficiency of treatments by optimising resource allocation •Task-sharing approaches with non-specialists have been effective in a growing number of psychological treatment trials, particularly in low-resource contexts, when accompanied by adequate supervision •Peer-led supervision approaches have potential utility as part of task sharing
Local stakeholder interviews: To obtain contextually sensitive evidence about types and causes of common adolescent mental health problems; adaptive and maladaptive coping strategies; knowledge and attitudes towards help-seeking; and preferences and priorities for psychological support	•Adolescent help seeking is often driven by psychosocial stressors rather than overt psychiatric symptoms •Adolescents prioritise concrete, practical tips for problem resolution •Self-help is largely unfamiliar as a concept among the target population; face-to-face guidance may help to explain materials and strengthen engagement •Digital technology is appealing for adolescents (especially use of films/animations), but there is limited access to personal devices and distribution of handsets could arouse suspicion from parents, teachers and peers •Adolescents are generally opposed to parental/teacher involvement in counselling, whereas significant adults wish to be kept informed about problems and progress •School counsellors are less likely to have strong stigmatising connotations, relative to psychiatrists and other clinic-based mental health service providers •Mental health literacy of staff and support for service implementation can vary greatly between schools
Relevance mapping: To identify evidence-based practice elements from global research literature that can be applied most widely to presenting problems in the target population	•Relative to other individual practice elements, problem solving offers the most parsimonious coverage to the range of presenting problems likely to occur in the target population •This includes a substantial proportion of psychosocial problems that do not correspond precisely to standardised mental health symptom inventories, but may nevertheless be associated with elevated distress and functional impairment •The full international literature, as well as the subset of studies in non-Western contexts, all showed similar support for problem solving