Effectiveness of a School-Based Indicated Early Intervention Program for Māori and Pacific Adolescents

A comparison of the effectiveness of cognitive behavioural interventions based on delivery features for elevated symptoms of depression in adolescents: A systematic review

Background

Depression is a public health problem and common amongst adolescents. Cognitive behavioural therapy (CBT) is widely used to treat adolescent depression but existing research does not provide clear conclusions regarding the relative effectiveness of different delivery modalities.

Objectives

The primary aim is to estimate the relative efficacy of different modes of CBT delivery compared with each other and control conditions for reducing depressive symptoms in adolescents. The secondary aim is to compare the different modes of delivery with regard to intervention completion/attrition (a proxy for intervention acceptability).

Search Methods

The Cochrane Depression, Anxiety and Neurosis Clinical Trials Register was searched in April 2020. MEDLINE, PsycInfo, EMBASE, four other electronic databases, the CENTRAL trial registry, Google Scholar and Google were searched in November 2020, together with reference checking, citation searching and hand-searching of two databases.

Selection Criteria

Randomised controlled trials (RCTs) of CBT interventions (irrespective of delivery mode) to reduce symptoms of depression in young people aged 10-19 years with clinically relevant symptoms or diagnosis of depression were included.

Data Collection and Analysis

Screening and data extraction were completed by two authors independently, with discrepancies addressed by a third author. CBT interventions were categorised as follows: group CBT, individual CBT, remote CBT, guided self-help, and unguided self-help. Effect on depressive symptom score was estimated across validated self-report measures using Hedges' g standardised mean difference. Acceptability was estimated based on loss to follow-up as an odds ratio. Treatment rankings were developed using the surface under the cumulative ranking curve (SUCRA). Pairwise meta-analyses were conducted using random effects models where there were two or more head-to-head trials. Network analyses were conducted using random effects models.

Main Results

Sixty-eight studies were included in the review. The mean age of participants ranged from 10 to 19.5 years, and on average 60% of participants were female. The majority of studies were conducted in schools (28) or universities (6); other settings included primary care, clinical settings and the home. The number of CBT sessions ranged from 1 to 16, the frequency of delivery from once every 2 weeks to twice a week and the duration of each session from 20 min to 2 h. The risk of bias was low across all domains for 23 studies, 24 studies had some concerns and the remaining 21 were assessed to be at high risk of bias. Sixty-two RCTs (representing 6435 participants) were included in the pairwise and network meta-analyses for post-intervention depressive symptom score at post-intervention. All pre-specified treatment and control categories were represented by at least one RCT. Although most CBT approaches, except remote CBT, demonstrated superiority over no intervention, no approaches performed clearly better than or equivalent to another. The highest and lowest ranking interventions were guided self-help (SUCRA 83%) and unguided self-help (SUCRA 51%), respectively (very low certainty in treatment ranking). Nineteen RCTs (3260 participants) were included in the pairwise and network meta-analyses for 6 to 12 month follow-up depressive symptom score. Neither guided self-help nor remote CBT were evaluated in the RCTs for this time point. Effects were generally attenuated for 6- to 12-month outcomes compared to posttest. No interventions demonstrated superiority to no intervention, although unguided self-help and group CBT both demonstrated superiority compared to TAU. No CBT approach demonstrated clear superiority over another. The highest and lowest ranking approaches were unguided self-help and individual CBT, respectively. Sixty-two RCTs (7347 participants) were included in the pairwise and network meta-analyses for intervention acceptability. All pre-specified treatment and control categories were represented by at least one RCT. Although point estimates tended to favour no intervention, no active treatments were clearly inferior. No CBT approach demonstrated clear superiority over another. The highest and lowest ranking active interventions were individual CBT and group CBT respectively. Pairwise meta-analytic findings were similar to those of the network meta-analysis for all analyses. There may be age-based subgroup effects on post-intervention depressive symptoms. Using the no intervention control group as the reference, the magnitudes of effects appear to be larger for the oldest age categories compared to the other subgroups for each given comparison. However, they were generally less precise and formal testing only indicated a significant difference for group CBT. Findings were robust to pre-specified sensitivity analyses separating out the type of placebo and excluding cluster-RCTs, as well as an additional analysis excluding studies where we had imputed standard deviations.

Authors' Conclusions

At posttreatment, all active treatments (group CBT, individual CBT, guided self-help, and unguided self-help) except for remote CBT were more effective than no treatment. Guided self-help was the most highly ranked intervention but only evaluated in trials with the oldest adolescents (16-19 years). Moreover, the studies of guided self-help vary in the type and amount of therapist support provided and longer-term results are needed to determine whether effects persist. The magnitude of effects was generally attenuated for 6- to 12-month outcomes. Although unguided self-help was the lowest-ranked active intervention at post-intervention, it was the highest ranked at follow-up. This suggests the need for further research into whether interventions with self-directed elements enable young people to maintain effects by continuing or revisiting the intervention independently, and whether therapist support would improve long-term outcomes. There was no clear evidence that any active treatments were more acceptable to participants than any others. The relative effectiveness of intervention delivery modes must be taken into account in the context of the needs and preferences of individual young people, particularly as the differences between effect sizes were relatively small. Further research into the type and amount of therapist support that is most acceptable to young people and most cost-effective would be particularly useful.

Long-term effects of psychosocial interventions for adolescents on depression and anxiety: a systematic review and meta-analysis

Background

Adolescence represents a distinctive phase of development, and variables linked to this developmental period could affect the efficiency of prevention and treatment for depression and anxiety, as well as the long-term prognosis. The objectives of this study were to investigate the long-term effectiveness of psychosocial interventions for adolescents on depression and anxiety symptoms and to assess the influence of different intervention parameters on the long-term effects.

Methods

In this systematic review and meta-analysis, we searched five databases (Cochrane Library, Embase, Medline, PsychInfo, Web of Science) and trial registers for relevant papers published between database inception and Aug 11, 2022, with no restrictions on the language or region in which the study was conducted. An updated search was performed on Oct 3, 2023. Randomised controlled trials of psychosocial interventions targeting specifically adolescents were included if they assessed outcomes at 1-year post-intervention or more. The risk of bias in the results was assessed using the Cochrane RoB 2.0. Between-study heterogeneity was estimated using the I2 statistic. The primary outcome was depression and studies were pooled using a standardised mean difference, with associated 95% confidence interval, p-value and I2. The study protocol was pre-registered on PROSPERO (CRD42022348668).

Findings

57 reports (n = 46,678 participants) were included in the review. Psychosocial interventions led to small reductions in depressive symptoms, with standardised mean difference (SMD) at 1-year of -0.08 (95% CI: -0.20 to -0.03, p = 0.002, I2 = 72%), 18-months SMD = -0.12, 95% CI: -0.22 to -0.01, p = 0.03, I2 = 63%) and 2-years SMD = -0.12 (95% CI: -0.20 to -0.03, p = 0.01, I2 = 68%). Sub-group analyses indicated that targeted interventions produced stronger effects, particularly when delivered by trained mental health professionals (K = 18, SMD = -0.24, 95% CI: -0.38 to -0.10, p = 0.001, I2 = 60%). No effects were detected for anxiety at any assessment.

Interpretation

Psychosocial interventions specifically targeting adolescents were shown to have small but positive effects on depression symptoms but not anxiety symptoms, which were sustained up to 2 years. These findings highlight the potential population-level preventive effects if such psychosocial interventions become widely implemented in accessible settings, such as schools. Future trials should include a longer term-follow-up at least at 12 months, in order to determine whether the intervention effects improve, stay the same or wear off over time.

Funding

UKRIMedical Research Council.

Development of guidelines for school staff on supporting students who self-harm: a Delphi study

OBJECTIVE

Self-harm is a major public health issue that significantly impacts communities, making early intervention and prevention paramount in addressing this public health issue. This study aimed to develop evidence-based, culturally responsive, safe, and practical guidelines to assist school staff in effectively supporting students who self-harm.

METHODS

This Delphi study comprised of a five-step process, oversighted by a Rōpū Mātanga Māori (Māori clinical and cultural governance group), and drawing on the expertise and knowledge gained from existing literature, interviews with stakeholders, and two panels of experts (youth and stakeholders). The Rōpū Mātanga Māori ensured accountability to the principles of Te Tiriti o Waitangi (Treaty of Waitangi) and kept Māori processes central to the research aims. The panels completed two rounds of questionnaires, rating their endorsement of each statement. Statements rated as important or essential by 80% or more of both panels and Māori participants were included in the final guidelines. The Rōpū Mātanga Māori reviewed any remaining statements to determine inclusion.

RESULTS

Following the five-step process, 305 statements were included in the guidelines. These statements provided guiding actions that endorsed communication, collaborative responsibility, and wellbeing and a student-centred approach.

CONCLUSION

The guidelines provide guidance to all school staff that is culturally responsive and safe, consensus-based, and evidence-based. It is informed by the voices and experiences of young people and those who support them.

School-based depression and anxiety prevention programs: An updated systematic review and meta-analysis

Depression and anxiety are often first experienced during childhood and adolescence, and interest in the prevention of these disorders is growing. The focus of this review was to assess the effectiveness of psychological prevention programs delivered in schools, and to provide an update to our previous review from five years ago (Werner-Seidler, Perry, Calear, Newby, & Christensen, 2017). Three electronic databases were systematically searched for published articles of randomised controlled trials (RCTs) evaluating the efficacy of school-based prevention programs until October 2020. There were 130 articles that met inclusion criteria, representing 118 unique trials and 45,924 participants. Small between-group effect sizes for depression (g = 0.21) and anxiety (g = 0.18) were detected immediately post-intervention. Subgroup analyses suggested that targeted prevention programs (for young people with risk factors or symptoms) were associated with significantly greater effect sizes relative to universal programs for depression, which was confirmed by meta-regression. There was also some evidence that external providers conferred some benefit over school-staff delivered programs. Overall, study quality was moderate and no association between risk of bias and effect size was detected. School-delivered psychological prevention programs have small effects in reducing symptoms of depression and anxiety. Refinement of these programs, and knowledge about how they can be sustainably delivered in schools beyond the trial period is now needed for population-level preventive effects. Systematic Review Registration Number: PROPSERO - CRD42020188323.

School-based interventions to prevent anxiety, depression and conduct disorder in children and young people: a systematic review and network meta-analysis

Background

Schools in the UK increasingly have to respond to anxiety, depression and conduct disorder as key causes of morbidity in children and young people.

Objective

The objective was to assess the comparative effectiveness of educational setting-based interventions for the prevention of anxiety, depression and conduct disorder in children and young people.

Design

This study comprised a systematic review, a network meta-analysis and an economic evaluation.

Data sources

The databases MEDLINE, EMBASE™ (Elsevier, Amsterdam, the Netherlands), PsycInfo® (American Psychological Association, Washington, DC, USA) and Cochrane Central Register of Controlled Trials (CENTRAL) were searched to 4 April 2018, and the NHS Economic Evaluation Database (NHS EED) was searched on 22 May 2019 for economic evaluations. No language or date filters were applied.

Main outcomes

The main outcomes were post-intervention self-reported anxiety, depression or conduct disorder symptoms.

Review methods

Randomised/quasi-randomised trials of universal or targeted interventions for the prevention of anxiety, depression or conduct disorder in children and young people aged 4–18 years were included. Screening was conducted independently by two reviewers. Data extraction was conducted by one reviewer and checked by a second. Intervention- and component-level network meta-analyses were conducted in OpenBUGS. A review of the economic literature and a cost–consequence analysis were conducted.

Results

A total of 142 studies were included in the review, and 109 contributed to the network meta-analysis. Of the 109 studies, 57 were rated as having an unclear risk of bias for random sequence generation and allocation concealment. Heterogeneity was moderate. In universal secondary school settings, mindfulness/relaxation interventions [standardised mean difference (SMD) –0.65, 95% credible interval (CrI) –1.14 to –0.19] and cognitive–behavioural interventions (SMD –0.15, 95% CrI –0.34 to 0.04) may be effective for anxiety. Cognitive–behavioural interventions incorporating a psychoeducation component may be effective (SMD –0.30, 95% CrI –0.59 to –0.01) at preventing anxiety immediately post intervention. There was evidence that exercise was effective in preventing anxiety in targeted secondary school settings (SMD –0.47, 95% CrI –0.86 to –0.09). There was weak evidence that cognitive–behavioural interventions may prevent anxiety in universal (SMD –0.07, 95% CrI –0.23 to 0.05) and targeted (SMD –0.38, 95% CrI –0.84 to 0.07) primary school settings. There was weak evidence that cognitive–behavioural (SMD –0.04, 95% CrI –0.16 to 0.07) and cognitive–behavioural + interpersonal therapy (SMD –0.18, 95% CrI –0.46 to 0.08) may be effective in preventing depression in universal secondary school settings. Third-wave (SMD –0.35, 95% CrI –0.70 to 0.00) and cognitive–behavioural interventions (SMD –0.11, 95% CrI –0.28 to 0.05) incorporating a psychoeducation component may be effective at preventing depression immediately post intervention. There was no evidence of intervention effectiveness in targeted secondary, targeted primary or universal primary school settings post intervention. The results for university settings were unreliable because of inconsistency in the network meta-analysis. A narrative summary was reported for five conduct disorder prevention studies, all in primary school settings. None reported the primary outcome at the primary post-intervention time point. The economic evidence review reported heterogeneous findings from six studies. Taking the perspective of a single school budget and based on cognitive–behavioural therapy intervention costs in universal secondary school settings, the cost–consequence analysis estimated an intervention cost of £43 per student.

Limitations

The emphasis on disorder-specific prevention excluded broader mental health interventions and restricted the number of eligible conduct disorder prevention studies. Restricting the study to interventions delivered in the educational setting may have limited the number of eligible university-level interventions.

Conclusions

There was weak evidence of the effectiveness of school-based, disorder-specific prevention interventions, although effects were modest and the evidence not robust. Cognitive–behavioural therapy-based interventions may be more effective if they include a psychoeducation component.

Future work

Future trials for prevention of anxiety and depression should evaluate cognitive–behavioural interventions with and without a psychoeducation component, and include mindfulness/relaxation or exercise comparators, with sufficient follow-up. Cost implications must be adequately measured.

Study registration

This study is registered as PROSPERO CRD42016048184.

Funding

This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 9, No. 8. See the NIHR Journals Library website for further project information.

Review: Delivering mental health support within schools and colleges - a thematic synthesis of barriers and facilitators to implementation of indicated psychological interventions for adolescents

BACKGROUND

Increasing the role of schools and colleges in the provision of mental health services for young people has the potential to improve early intervention and access to treatment. We aimed to understand what factors influence the successful implementation of indicated psychological interventions within schools and colleges to help guide increased provision of mental health support within education settings.

METHODS

Systematic search for studies that have reported barriers or facilitators to the implementation of indicated interventions for adolescent emotional disorders delivered within schools and further education/sixth form colleges (CRD42018102830). Databases searched were EMBASE, MEDLINE, PsycINFO, CINAHL, British Nursing Index, ASSIA, ERIC and British Education Index. A thematic synthesis of factors reported to impact implementation was conducted.

RESULTS

Two thousand five hundred and sixty-nine records and 177 full texts were screened. Fifty studies were identified for inclusion, all of which were of school-based interventions. Eleven analytic themes were developed encompassing intervention characteristics, organisational capacity, training and technical assistance, provider characteristics and community-level factors. Findings indicate the need to select appropriate interventions, consider logistical challenges of the school context and provide training and supervision to enable staff to deliver interventions with fidelity. However, structural and environmental support is required for these facilitators to have the greatest impact on successful implementation.

CONCLUSIONS

Implementing indicated school-based mental health interventions is challenging. Those involved in planning school-based mental health initiatives must be alert to the impact of factors on multiple interacting levels. There is a lack of research on implementing mental health support within further education and sixth form colleges.

KEY PRACTITIONER MESSAGE

Increased utilisation of schools and colleges as a setting for early intervention has been proposed as a means of improving access to mental health treatment, but successful implementation of mental health interventions within educational settings is challenging. Based on a synthesis of current evidence, we recommend that young people and education professionals should be involved in the selection of school-based interventions to ensure they are acceptable and practical to deliver within the logistical constraints of the school environment. Those delivering interventions within schools, as well as staff involved in identifying young people who might benefit from these interventions, must receive high-quality ongoing training and support. Senior school leaders play an important role in championing mental health interventions and developing a school culture that prioritises mental well-being. Health and education policy should be designed to promote a cross-sector focus on the emotional health of young people. There is a lack of evidence on the implementation of indicated psychological interventions within sixth form and further education colleges.

Practitioner Review: Effectiveness of indicated school-based interventions for adolescent depression and anxiety - a meta-analytic review

BACKGROUND

Interest in delivering psychological interventions within schools to facilitate early intervention is increasing. However, most reviews have focused on universal or preventative programmes rather than interventions designed to decrease existing symptoms of depression or anxiety. This paper aims to provide a meta-analytic review of randomised controlled trials of indicated psychological interventions for young people aged 10-19 with elevated symptoms of depression and/or anxiety.

METHODS

Eight electronic databases were systematically searched from inception to April 2019 for eligible trials. Study quality was assessed using two scales designed to evaluate psychotherapy intervention trials. Random effects meta-analyses were conducted separately for trials that recruited participants based on symptoms of depression and based on symptoms of anxiety.

RESULTS

Data from 45 trials were analysed. Most interventions studied used cognitive and behavioural strategies. Few studies met methodological quality criteria, but effect size was not associated with study quality. Indicated school-based interventions had a small effect on reducing depression symptoms (SMD = .34, 95% CI -0.48, -0.21) and a medium effect on reducing anxiety symptoms (SMD = -.49, 95% CI -0.79, -0.19) immediately postintervention. Subgroup analyses indicated that interventions delivered by internal school staff did not have significant effects on symptoms. Reductions in depression were maintained at short-term (≤6 months) but not medium (>6 months ≤ 12) or long-term (>12-month) follow-up. Reductions in anxiety symptoms were not maintained at any follow-up.

CONCLUSIONS

Indicated school-based interventions are effective at reducing symptoms of depression and anxiety in adolescents immediately postintervention but there is little evidence that these reductions are maintained. Interventions delivered by school staff are not supported by the current evidence base. Further high-quality randomised controlled trials incorporating assessment of longer-term outcomes are needed to justify increased investment in school-based interventions for adolescent depression and anxiety.

Motivational interviewing and culture for urban Native American youth (MICUNAY): A randomized controlled trial

To date, few programs that integrate traditional practices with evidence-based practices have been developed, implemented, and evaluated with urban American Indians/Alaska Natives (AI/ANs) using a strong research design. The current study recruited urban AI/AN teens across northern, central, and southern California during 2014-2017 to participate in a randomized controlled trial testing two cultural interventions that addressed alcohol and other drug (AOD) use. Adolescents were 14-18 years old (inclusive), and either verbally self-identified as AI/AN or were identified as AI/AN by a parent or community member. We tested the added benefit of MICUNAY (Motivational Interviewing and Culture for Urban Native American Youth) to a CWG (Community Wellness Gathering). MICUNAY was a group intervention with three workshops that integrated traditional practices with motivational interviewing. CWGs were cultural events held monthly in each city. AI/AN urban adolescents (N = 185) completed a baseline survey, were randomized to MICUNAY + CWG or CWG only, and then completed a three- and six-month follow-up. We compared outcomes on AOD use, spirituality, and cultural identification. Overall, AOD use remained stable over the course of the study, and we did not find significant differences between these two groups over time. It may be that connecting urban AI/AN adolescents to culturally centered activities and resources is protective, which has been shown in other work with this population. Given that little work has been conducted in this area, longer term studies of AOD interventions with urban AI/AN youth throughout the U.S. are suggested to test the potential benefits of culturally centered interventions.

A Systematic Scoping Review of the Resilience Intervention Literature for Indigenous Adolescents in CANZUS Nations

Background: The concept of resilience offers a strengths-based framework for interventions to enhance Indigenous adolescent social and emotional well-being. Resilience interventions in or with schools encompass individual, social, and environmental factors that encourage health-promoting behaviors and assist adolescents in navigating toward resources that can sustain their health and well-being in times of adversity. This scoping review examined the literature on resilience-enhancing interventions for Indigenous adolescent students in Canada, Australia, New Zealand, and the United States (CANZUS nations). Intervention strategies, adherence to theoretical constructs, and outcomes were analyzed. Methods: A systematic search was conducted of intervention studies aimed at improving Indigenous adolescent resilience and published in CANZUS nations between January 1990 and May 2016. Eleven peer-reviewed databases and 11 websites and clearing houses were searched for relevant studies. Following double-blinded screening, a total of 16 intervention papers were included for analysis. Study characteristics were identified and study quality was assessed using appropriate assessment tools. Results: Twelve interventions (75%) were delivered in school settings and four (25%) were community-based, conducted in partnership with schools. Seven publications (44%) reported interventions focused exclusively on fostering individual resilience. Another seven (44%) included components that aimed to build staff, school, and/or community capacity to support adolescent resilience, and two (12.5%) had community/school capacity-building as the primary focus. Culturally based approaches to enhancing resilience were evident in most studies (81%). The publications documented the use of a range of program models, processes, and activities aligned with resilience theory. Positive outcomes were reported for improved individual assets (e.g., strengthened self-esteem and Indigenous identity), environmental resources (e.g., increased peer support and social/community connection), and increased community capacity (e.g., increased youth training and leadership opportunities). On average, study quality was assessed as moderate to high. The strongest evidence of intervention effectiveness was for improvements in mental health symptoms and outcomes. Conclusion: Interventions indicated strong alignment with ecological and culturally based resilience theories and models. While the results of the studies indicate some positive impacts on the resilience of Indigenous adolescents, future evaluations should aim to ensure high study quality and focus on measuring strengths-based resilience outcomes.

Indicated preventive interventions for depression in children and adolescents: A meta-analysis and meta-regression

Depression contributes about 2% to the global burden of disease. A first onset of depressive disorder or subsyndromal depressive symptoms is common in adolescence, indicating that early prevention is a priority. However, trials of preventive interventions for depression in youths show conflicting results. This systematic review and meta-analysis investigated the effectiveness of group-based cognitive behavioral therapy (GB-CBT) as a preventive intervention targeting subsyndromal depression in children and adolescents. In addition, the impact of different covariates (type of comparator and use of booster sessions) was assessed. Relevant articles were identified from previous systematic reviews, and supplemented with an electronic search spanning from 01/09/2014 to 28/02/2018. The retrieved articles were assessed for eligibility and risk of bias. Relevant data were extracted. Intervention effectiveness was pooled using a random-effects model and the impact of covariates assessed using meta-regression. 38 eligible articles (34 trials) were obtained. The analysis showed GB-CBT to significantly reduce the incidence (relative risk 0.43, 95% CI 0.21-0.87) and symptoms (Cohen's d -0.22, 95% CI -0.32 to -0.11) of depression at post-test compared to all controls. Comparisons with passive comparators suggested that the effect decayed over time. However, compared to active controls, a significant intervention effect was evident only after 12 month or more. Our results suggest that the preventive effect of GB-CBT wears off, but still lasts longer than the effect of active comparators. Only a few studies included booster sessions, precluding firm conclusions. Future studies should clarify to what extent maintenance strategies can prolong the preventive effect of GB-CBT.

Cognitive behavioural therapy (CBT), third-wave CBT and interpersonal therapy (IPT) based interventions for preventing depression in children and adolescents

BACKGROUND

Depression is common in young people. It has a marked negative impact and is associated with self-harm and suicide. Preventing its onset would be an important advance in public health. This is an update of a Cochrane review that was last updated in 2011.

OBJECTIVES

To determine whether evidence-based psychological interventions (including cognitive behavioural therapy (CBT), interpersonal therapy (IPT) and third wave CBT)) are effective in preventing the onset of depressive disorder in children and adolescents.

SEARCH METHODS

We searched the specialised register of the Cochrane Common Mental Disorders Group (CCMDCTR to 11 September 2015), which includes relevant randomised controlled trials from the following bibliographic databases: The Cochrane Library (all years), EMBASE (1974 to date), MEDLINE (1950 to date) and PsycINFO (1967 to date). We searched conference abstracts and reference lists of included trials and reviews, and contacted experts in the field.

SELECTION CRITERIA

We included randomised controlled trials of an evidence-based psychological prevention programme compared with any comparison control for young people aged 5 to 19 years, who did not currently meet diagnostic criteria for depression.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials for inclusion and rated their risk of bias. We adjusted sample sizes to take account of cluster designs and multiple comparisons. We contacted trial authors for additional information where needed. We assessed the quality of evidence for the primary outcomes using GRADE.

MAIN RESULTS

We included 83 trials in this review. The majority of trials (67) were carried out in school settings with eight in colleges or universities, four in clinical settings, three in the community and four in mixed settings. Twenty-nine trials were carried out in unselected populations and 53 in targeted populations.For the primary outcome of depression diagnosis at medium-term follow-up (up to 12 months), there were 32 trials with 5965 participants and the risk of having a diagnosis of depression was reduced for participants receiving an intervention compared to those receiving no intervention (risk difference (RD) -0.03, 95% confidence interval (CI) -0.05 to -0.01; P value = 0.01). We rated this evidence as moderate quality according to the GRADE criteria. There were 70 trials (73 trial arms) with 13,829 participants that contributed to the analysis for the primary outcome of depression symptoms (self-rated) at the post-intervention time point, with results showing a small but statistically significant effect (standardised mean difference (SMD) -0.21, 95% CI -0.27 to -0.15; P value < 0.0001). This effect persisted to the short-term assessment point (up to three months) (SMD -0.31, 95% CI -0.45 to -0.17; P value < 0.0001; 16 studies; 1558 participants) and medium-term (4 to 12 months) assessment point (SMD -0.12, 95% CI -0.18 to -0.05; P value = 0.0002; 53 studies; 11,913 participants); however, the effect was no longer evident at the long-term follow-up. We rated this evidence as low to moderate quality according to the GRADE criteria.The evidence from this review is unclear with regard to whether the type of population modified the overall effects; there was statistically significant moderation of the overall effect for depression symptoms (P value = 0.0002), but not for depressive disorder (P value = 0.08). For trials implemented in universal populations there was no effect for depression diagnosis (RD -0.01, 95% CI -0.03 to 0.01) and a small effect for depression symptoms (SMD -0.11, 95% CI -0.17 to -0.05). For trials implemented in targeted populations there was a statistically significantly beneficial effect of intervention (depression diagnosis RD -0.04, 95% CI -0.07 to -0.01; depression symptoms SMD -0.32, 95% CI -0.42 to -0.23). Of note were the lack of attention placebo-controlled trials in targeted populations (none for depression diagnosis and four for depression symptoms). Among trials implemented in universal populations a number used an attention placebo comparison in which the intervention consistently showed no effect.

AUTHORS' CONCLUSIONS

Overall the results show small positive benefits of depression prevention, for both the primary outcomes of self-rated depressive symptoms post-intervention and depression diagnosis up to 12 months (but not beyond). Estimates of numbers needed to treat to benefit (NNTB = 11) compare well with other public health interventions. However, the evidence was of moderate to low quality using the GRADE framework and the results were heterogeneous. Prevention programmes delivered to universal populations showed a sobering lack of effect when compared with an attention placebo control. Interventions delivered to targeted populations, particularly those selected on the basis of depression symptoms, had larger effect sizes, but these seldom used an attention placebo comparison and there are practical difficulties inherent in the implementation of targeted programmes. We conclude that there is still not enough evidence to support the implementation of depression prevention programmes.Future research should focus on current gaps in our knowledge. Given the relative lack of evidence for universal interventions compared with attention placebo controls and the poor results from well-conducted effectiveness trials of universal interventions, in our opinion any future such trials should test a depression prevention programme in an indicated targeted population using a credible attention placebo comparison group. Depressive disorder as the primary outcome should be measured over the longer term, as well as clinician-rated depression. Such a trial should consider scalability as well as the potential for the intervention to do harm.