Economic evaluation

As described in Chapter 1, the aim of the economic study was to assess the costs and consequences for intervention components, or combinations of components, that were found to be effective, compared with usual curriculum, in the NMA. Costs and consequences were considered separately for:

• targeted interventions to prevent anxiety, depression or conduct disorders among (1) primary school-aged children, (2) secondary school-aged children/young people and (3) university-aged young people
• universal interventions for (1) primary school-aged children, (2) secondary school-aged children and (3) university-aged young people.

For the economic evaluation, we included interventions for which there was robust evidence of an intervention effect in one of the populations considered in the NMA. The intervention-level NMA results (see Chapters 4 and 5) found that CBT interventions (including those combined with IPT) were effective, compared with usual curriculum, at the post-intervention follow-up time point for universal secondary populations. There was also evidence that mindfulness/relaxation interventions reduced symptoms of anxiety. However, the findings were not considered robust because of small study size and unclear risk of bias for the key domains of randomisation and allocation concealment. Similarly, there was evidence that exercise reduced symptoms of anxiety in the targeted secondary analysis. However, this was based on a single study on a network ‘spur’, which was judged to be at unclear risk of bias. There was potential inconsistency in the tertiary/university setting analyses and NMA findings were not reported. We therefore analysed costs and consequences for CBT and CBT + IPT in a universal secondary population. For completeness, we extrapolate the costs for CBT interventions to primary and targeted secondary settings (as CBT was included in the NMA for these settings).

Results from the component NMA suggested that the only intervention component for which there was robust evidence of effectiveness, compared with usual curriculum, was the inclusion of a psychoeducation component in CBT interventions in a universal secondary school setting. We therefore only present costs and consequences for the inclusion of a psychoeducation component in a CBT intervention in the universal secondary population.

If sufficient evidence was available, we planned to conduct full model-based cost-effectiveness analyses for all identified groups. However, there was no robust evidence that any of the interventions were effective at ≥ 6 months post intervention, based on the NMAs. We therefore did not consider that a full model-based cost-effectiveness analysis would be of value, as it was unlikely to demonstrate cost-effectiveness of any of the interventions, compared with usual curriculum, in any of the populations, based on the evidence identified in our review.

The economic study also aimed to review previous economic evaluations of school-based interventions to provide up-to-date and rigorously collated information on costs and cost-effectiveness to inform both future intervention development and implementation decisions. We aimed to complement the effectiveness results by reviewing current literature describing the costs and cost-effectiveness of educational setting-based interventions for preventing anxiety, depression or conduct disorder among CYP. We also aimed to undertake a microcosting study for effective interventions, assigning appropriate costs to the constituent components of the interventions when feasible, for use in the cost–consequence analysis.

Methods

We first describe the methods for the narrative review of previous economic evaluations of educational setting-based interventions that aimed to prevent anxiety, depression or conduct disorder among CYP. We then describe the methods for the microcosting study of the inclusion of a psychoeducation component in universal secondary CBT interventions described in a cost–consequence analysis.

Narrative review

Search strategy

We searched for relevant studies describing economic evaluations of educational setting-based preventative interventions in several ways:

• The body of abstracts identified in the detailed systematic review described in Chapter 2 was restricted by terms to identify costing studies (e.g. ‘economic evaluation’, ‘cost’).
• The search strategy used for the systematic review (described in Chapter 2 and Appendix 1, and carried out on 4 April 2018) was reproduced and applied to the full extent of the NHS Economic Evaluation Database (NHS EED; date range searched: 1968 to 2014) on 22 May 2019 (see Appendix 8).
• Potentially relevant articles were sought by searching for economic evaluations of interventions described in the clinical effectiveness studies included in the NMA (see Chapters 4 and 5). The 142 included articles were inspected for details of trial registration and, when present, the registration record was searched for ‘cost’ or ‘economic’, which might have indicated an intention to conduct an economic analysis. References to the words ‘cost’ or ‘economic’ in the text of the included articles themselves were followed up when appropriate. Authors were contacted to request details of publications if we believed that an economic study may have been carried out but were unable to locate the report.
• As a supplemental search, economic evaluations associated with the interventions tested in the 142 included effectiveness articles were sought using the Google Scholar (Google Inc., Mountain View, CA, USA) forward citation search functionality.252,253

The original searches described in Chapter 2 were based on RCTs and may have missed relevant decision models. Therefore, a scoping search was carried out in MEDLINE to assess the likelihood of modelling articles having been missed (see Appendix 8), with the intention of reproducing and repeating the initial searches without the RCT restriction if it appeared that a substantial body of modelling articles had been missed.

Inclusion criteria

The following inclusion criteria were agreed by Joanna C Thorn, Deborah M Caldwell and Nicky J Welton prior to screening articles:

• educational setting-based intervention
• intervention designed explicitly to prevent anxiety, depression or conduct disorder
• intervention aimed at CYP aged 4–18 years
• original study based on a RCT with an embedded economic evaluation or an economic decision model.

All population, intervention, comparator and outcome inclusion criteria for the effectiveness review were reflected in the economic search. We did not include papers that were written in languages other than English, conference abstracts or review papers. Titles and abstracts were screened for inclusion, and full texts were obtained for all articles that either clearly met the inclusion criteria or for which inclusion was unclear. Screening of both abstracts and full texts was carried out by one author (JT), with a second opinion (DMC) sought when necessary. Reasons for exclusion were recorded for articles rejected after full-text screening.

Data extraction and quality control

Data covering study characteristics (publication date, unit of randomisation, location, setting, study design, type of model, model time horizon or empirical follow-up period, size of study, comparator), intervention details (description of intervention, intervention cost, condition targeted, population, type of intervention) and economic details (type of economic analysis, outcomes measured, sources of outcomes, discount rate, resources included and source of resources, cost year, currency, perspective) were extracted from included studies using a bespoke form in Microsoft Access^® (Microsoft Corporation, Redmond, WA, USA). Verbatim descriptions of the study conclusions were also extracted. The quality of the included studies was qualitatively assessed against the Drummond et al.254 10-point checklist for RCTs and the Philips et al.255 checklist for decision models. Costs were converted to Great British pounds using purchasing power parity figures256 and inflated to 2018 equivalents257 for comparison purposes.

Data synthesis

Included interventions were categorised as targeted (indicated or selective) or universal, and the cost-effectiveness analyses were described in a narrative review.

Intervention costing

The NMA results (see Tables 3, 4, 7 and 8) suggested that CBT-based interventions were the most likely to produce positive outcomes, with CBT + IPT-based interventions also showing some indication of effect for preventing depression in a universal secondary-age population. Results from the component NMA indicated that the only component for which there was evidence of a beneficial effect in universal secondary CBT interventions was a psychoeducation component, with CBT interventions with psychoeducational components reducing the standardised anxiety score by –0.39 (95% CrI –0.78 to 0.01). Therefore, our intervention costing analysis (and subsequent component breakdown) focused on CBT interventions that incorporated identifiable psychoeducation components and CBT + IPT interventions. As there are considerable similarities between interventions designed to prevent depression and those focusing on anxiety (with some interventions explicitly targeting both), we included both depression and anxiety interventions in the costing estimate without distinguishing between them.

Studies describing universal secondary CBT interventions with a psychoeducation component were identified from the systematic review described in Chapter 2. Details of the interventions were extracted (i.e. year of publication, number of sessions offered, average session duration, size of group, number of group leaders, professional background of leaders, provision of a manual, training, materials, provision of parent sessions and other costs). Further details of the interventions were sought from intervention websites and from linked papers describing the branded interventions in more detail. Through scrutinising the extracted data, an ‘indicative’ intervention was developed. Unit costs for the individual elements for a universal intervention in a secondary population were identified in the UK context, and cost estimates were calculated for the ‘indicative’ intervention. The CBT cost estimates were extrapolated to primary populations and targeted interventions. A similar extraction process was carried out for CBT + IPT interventions.

Component costing

When the CBT intervention was described in sufficient detail (either in the paper itself or by consulting the intervention manual), the approximate proportion of each intervention devoted to psychoeducation elements was estimated. Psychoeducation was defined to include the provision of information, the explanation of symptoms, advice on managing the condition and the provision of written materials,258 while excluding practical experiences (such as role play) and activities based on the individual’s own life experience. Intervention descriptions and manuals were scrutinised carefully, and elements of psychoeducation were identified. The approximate time commitment to each psychoeducation element was estimated, summed for each intervention and expressed as a proportion of the whole intervention. An approximate estimate of the cost that could be ascribed to psychoeducation components was derived based on the overall cost of the indicative intervention.

Cost–consequence analysis

The intervention costs and consequences (SMD relative to usual curriculum post intervention) that could be ascribed to the ‘indicative’ interventions and psychoeducation components are presented as a cost–consequence table (Table 19). If no effectiveness estimates are available relative to usual curriculum, the results relative to a waiting list are reported; if these are also not available, then the results relative to no intervention are presented.

Results

Narrative review of previous economic evaluations

Article selection

A flow diagram summarising the identification and selection of articles is given in Figure 16. A total of 434 titles and abstracts were screened for inclusion; full texts were obtained for 36 articles. Eight articles, reporting on six study time points, were deemed to meet the inclusion criteria.

FIGURE 16 Study selection process: flow diagram for review of economic evaluations. (Figure not reproduced here; see the original article.)

Only 3 of the 137 depression and anxiety effectiveness articles (2.2%) included in Chapters 4 and 5 were found to have published economic evaluations. Three further authors of effectiveness papers were contacted to request details of potential economic evaluations. All three authors confirmed that no economic study had been published, although one is still planning to complete and publish the study in future. Of the five included conduct disorder studies (see Chapter 7), only one (i.e. Fast Track247) had undergone economic evaluation. The additional scoping search carried out in MEDLINE to identify economic decision model papers returned 186 potentially relevant articles. The search identified both of the modelling papers that had already been identified in the original review,259,260 but did not identify any additional articles. Based on this finding, we did not conduct further searches for economic decision model papers in the other databases searched in the systematic review. Although there is a possibility that we may have missed some decision model papers, we think that this is unlikely.

Included studies characteristics

The six included studies were published between 2006 and 2017, with costs reported in currency years from 2003 to 2014. The numbers of participants in the studies describing RCTs ranged from 308 to 3357. Two studies described universal interventions, three studies reported on an indicated intervention (of which two included a universal component) and the final study considered both universal and indicated interventions. Two analyses were based on economic decision models (both Markov models) and four analyses were based on data from RCTs. The follow-up period ranged from 6 months to 14 years for the trial-based analysis, and the model horizons were 5 or 10 years. Interventions were compared with usual provision (n = 4) or no intervention (n = 2). Additional characteristics are summarised in Table 18, and the extracted data are provided in Appendix 8.

Quality of articles

The study by Mihalopoulos et al.260 met the majority of the Philips checklist criteria.255 However, the intervention was not described in adequate detail, half-cycle corrections were neither incorporated nor discussed and there were weaknesses in both the assessment of uncertainty and description of data incorporation. Lee et al.259 published a very detailed supplementary document alongside the article, thereby meeting most of the reporting requirements, although the cycle length was not explicitly stated and parameter distribution choices were stated but not justified. Structural uncertainty and heterogeneity did not appear to have been explored in either article.

The analysis reported by Anderson et al.261 lacked sensitivity analyses for exploring uncertainty and did not discuss generalisability, but was otherwise well reported. Although there was no discussion of generalisability or comparison with other studies and no subgroups were considered, the study by Stallard et al.262 generally conformed to the requirements of the Drummond checklist.254 The 2006/7 articles by Foster and Jones263,264 did not adequately report the effectiveness of the intervention, and did not include all costs that might have been relevant. Discounting was neither described fully nor justified, and results were not compared with those of other studies. As no incremental analysis was conducted in the 2010 study,250 the study quality was not assessed.

Costs and cost-effectiveness

A range of economic analysis perspectives was studied, including the health, social services, education and criminal justice sectors, leading to a wide range of resources being included in the analyses. Interventions were typically complex and ranged in cost from approximately £45 per participant to > £60,000. The intervention for conduct disorder involved multisystemic, multicomponent and sequentially delivered individual and group interventions over a 10-year period, whereas the interventions for depression and anxiety were all based on CBT methods. Outcomes considered in the economic analyses included utilities [either quality-adjusted life-years (QALYs) or DALYs averted], as well as other clinical outcomes. The studies are described in more detail below.

Prevention of anxiety

Stallard et al.159,262 studied a universal intervention for anxiety prevention in primary schools in the UK. The FRIENDS intervention is a CBT-based programme that teaches children to recognise anxiety and develop strategies to address anxious feelings. The intervention was delivered by either a teacher or an external health educator, and both were compared against usual curriculum provision in a three-arm trial. The cost-effectiveness of the programme was assessed at 6 months in terms of the cost per unit reduction in primary outcome (RCADS score), and a cost–utility analysis was conducted using the Child Health Utility-9 Dimensions (CHU-9D) instrument to measure health-related quality-of-life data from which QALYs were derived. The economic analyses were carried out from the joint health, social services and education sectors perspective. Therefore, resources considered in the study (measured using an adapted Client Service Receipt Inventory instrument administered by parental interview) included hospital stays, accident and emergency visits, outpatient appointments, general practitioner (GP) visits and visits to psychology practitioners or social workers, and medications. The scope of the study appeared to be condition-specific resource use, except for hospital events, which encompassed all-cause resource use. It was unclear whether use of social services was condition specific or all cause. A very detailed breakdown of the intervention costs was provided, leading to a total of £62.96 per child if the intervention was delivered by school staff and £59.16 per child if delivered by external health staff (inflated to 2018 costs). Point estimates suggested that the intervention was more costly, but less effective (by 0.004 QALYs), than the control, that is the intervention was dominated. The economic analysis provided further evidence that the intervention was unlikely to be cost-effective, with a probability of cost-effectiveness of < 35% at all societal willingness-to-pay values for the intervention delivered by health staff. Furthermore, the analysis was based on complete cases for CHU-9D measurements. This may have led to bias, as it is possible that those individuals without complete data were less likely to have benefited from the programme. The cost of teacher time for delivering the intervention was treated as zero. This strategy implies that there was no opportunity cost associated with alternative learning activities from the teachers’ point of view.

Prevention of depression

Three studies (one RCT and two decision models) addressed interventions aiming to prevent depression. The RCT evaluated the CBT-based Resourceful Adolescent Program (RAP) from the perspective of the NHS and social care in the UK.261 We note that, in the present review, the RAP was classified as CBT + IPT, a combined intervention type, in line with the description of the intervention in Merry et al.197 and Hetrick et al.68 The study was described in both a report to the funder and a journal article. The more recently published paper has been treated here as the primary account, with the funder report consulted for further detail when necessary. The RAP is a universal intervention that was delivered in secondary schools, recruiting young people aged 12–16 years. Cost-effectiveness was assessed after 12 months of follow-up in relation to both QALYs (measured using the EuroQoL-5 Dimensions questionnaire) and clinical symptoms of low mood (measured using the Mood and Feelings Questionnaire-Short Version). Resources considered in the study included hospital stays, accident and emergency visits, outpatient appointments, GP visits and visits to psychology practitioners. Details of medications were collected but not reported, as the data were considered unreliable. The cost associated with delivering the intervention (£46.15 per child in 2018 equivalent) was relatively small, and a detailed breakdown was reported. For both the cost-effectiveness and cost–utility analyses, the point estimates suggested that the intervention was both more costly and less effective than the control (usual class provision within school), albeit with considerable uncertainty around the results. The intervention was deemed ‘highly unlikely’ to be cost-effective.

The two model-based analyses were conducted in the Australian context following the Assessing Cost-Effectiveness in Prevention framework.259,260 The studies shared a common author, and both were based on ‘hypothetical’ interventions developed by the project team following a literature review and meta-analysis. In both cases, the intervention was compared with no intervention, focused on children aged 11–17 years, considered DALYs averted as the economic outcome measure and used Markov models. The earlier (2012) study260 involved a model time horizon of 5 years and a health sector perspective. The more recent (2017) model259 was extended to 10 years and included both health and education sectors in the perspective. Intervention costs were estimated by Lee et al.259 at £12.90 per child for the universal intervention and £259.25 per child for the indicated intervention (2018 prices). The incremental cost-effectiveness ratios (ICERs) were found to be AU$7350 per DALY averted for a universal intervention and AU$19,550 per DALY averted for the indicated intervention in Lee et al.,259 and AU$5400 per DALY averted for an indicated intervention in Mihalopoulos et al.260 Assessed against a standard societal willingness-to-pay threshold of $50,000 per DALY averted, both studies concluded that school-based preventative interventions represent good value for money. However, as the studies focused on the prevention of major depression with three health states only (healthy, diseased and dead), the lack of granularity in terms of addressing the spectrum of disease severity limits the usefulness of the analyses in informing implementation decisions.

Prevention of conduct disorder

Three articles, all by the same author group and relating to the same study, described the Fast Track intervention, designed to prevent conduct disorder in the USA. The intervention was assessed at two time points (10 years263,264 and 13 years250 post randomisation). Two articles described the same study at the same time point, with one reporting an ICER and the other reporting the net monetary benefit statistic. As these cost-effectiveness statistics would usually be reported together, and the articles are identical in many aspects, the two articles have been treated as one for the purposes of this review. The Fast Track intervention took a long-term approach to the prevention of conduct disorder. Children were identified as ‘at risk’ at age 6–7 years and were given intensive support through multiple activities over a 10-year period, including parent training, group meetings, friendship development and promotion of reading skills (see Chapter 7). The multifaceted intervention was very costly, at US$58,283 (cost year: 2014) (£60,478 in 2018 Great British pounds) per child.

The stated perspective of the economic analysis was that of a third-party payer, but the intervention cost was the only resource included. Cost-effectiveness at 10 years was found to be US$3,481,433 per case of conduct disorder averted, with only a 1% probability of cost-effectiveness at an assumed societal willingness-to-pay value of US$1M. However, the authors explicitly note that the intervention was designed for effectiveness, not cost-effectiveness. Possible future effects were addressed approximately by estimating the costs associated with an enduring criminal lifestyle, and incorporating this estimate into the societal willingness-to-pay value, but no other potential offsets (such as the effect on health or social care, or directly on the education system) were included in the analysis. Only the intervention was costed. A subgroup analysis suggested that the intervention may be cost-effective for children at the highest risk of developing conduct disorder; however, it was unclear whether this analysis was prespecified or conducted post hoc.

By the 13-year follow-up, evidence for cost-effectiveness had dissipated, and the study concluded that ‘[t]he most intensive psychosocial intervention ever fielded did not produce meaningful and consistent effects on costly outcomes’.250 This study took a much broader perspective than previously, but, citing the lack of intervention effect as a justification, the authors presented marginal effects for group differences for a number of resources, instead of deriving any formal cost-effectiveness statistics combining costs and outcomes. Relevant resources included health-care use, criminal justice interactions, substance use and educational service use. Full data sets were not available for all variables. For example, medication use was available for years 4–13 only, and health-care use was available for years 7–13 only. Costs associated with health-care use and delinquency were investigated, although no unit costs were reported for the resources used. Both outpatient mental health-care use and general any-cause health service use costs were higher in the control group, these costs being, respectively, US$1344 and US$1106 lower per participant in the intervention group. Costs associated with the criminal justice system showed no difference between the groups. Weaknesses in the trial development and conduct were identified, and tension arising from the differing background perspectives of the study team was apparent. For example, the author was critical of developmental psychology as a discipline, of the lack of data-sharing in the project and of the lack of prespecified analysis plans, leading to concerns over chance findings.

Intervention costs

Extracted elements of the interventions described in 20 papers evaluating universal CBT interventions with a psychoeducation component identified via the ICA (see Chapters 4 and 5) are given in Appendix 8. The number of sessions for children ranged from 3 to 30, with a median of 10 sessions. Session duration ranged from 35 to 120 minutes (median 50 minutes). Group sizes ranged from 4 to 30 participants, with a median of 25. Parent sessions formed part of the intervention in only five studies, with low attendance cited as an issue in two of these studies. The group leaders included teachers (n = 8), psychologists (n = 11) and students (n = 5) (sometimes in combination). Groups were led by either one (n = 12) or two (n = 7) individuals (the exact leadership was unclear in one study). Of the 12 groups led by one individual, four were led by psychologists and eight by teachers. Training for delivering the intervention (when described) took a number of forms, including self-participation in the intervention, workshops varying from 90 minutes to 5 days (n = 9, median 1 day) and co-leading a cohort. A facilitator manual was provided in 16 out of 20 interventions, and workbooks or worksheets were supplied in 13 out of 20 interventions.

A ‘typical’ universal secondary CBT intervention might, therefore, comprise 10 sessions of 50 minutes, each session each delivered to 25 children at a time by one teacher who had received 1 day of specific intervention training. Typically a manual would be provided for facilitators, and workbooks for the participants. Unit costs associated with these elements in the UK context are given in Appendix 8. This leads to an estimated overall intervention cost of £43 per student from the school budget perspective. At the school level, this would represent approximately £1825 per (small) two-form entry school, or £7300 per larger eight-form entry school in the first year. A two-form entry school is one that has an annual intake of two classes of approximately 30 students each, who then progress through the school as a stable cohort. An eight-form entry school is approximately four times as large. If this universal intervention were delivered in a primary school, the teacher costs would be slightly lower, leading to an approximate cost of £42 per student. Assuming that a targeted (indicated or selective) intervention would be delivered to a smaller group of students (e.g. 10), the cost per student would be £95 in a secondary setting or £91 in a primary setting. Similarly, based on three articles describing universal secondary CBT + IPT interventions, a typical CBT + IPT intervention might have both workbooks and a manual, and consist of 11 sessions of 60 minutes each, delivered by one teacher to 10 students after 2 days’ training. This leads to an estimated cost of £157 per student.

Component analysis

Seven CBT interventions were described in sufficient detail to attempt to assign a very approximate proportion of the intervention devoted to psychoeducation: e-couch (33%), ThisWayUp (40%), Penn Resilience Program (30%), LARS&LISA (20%), Op Volle Kracht (50%) and two unnamed interventions (12% and 100%). Overall, approximately one-third of the ‘typical’ intervention could be assigned as psychoeducation. The potential cost of incorporating a psychoeducation component might, therefore, represent approximately £14 per student (i.e. approximately £600 per two-form entry school or £2400 per eight-form entry school).

Cost–consequence analysis

Intervention costs and consequences in SMDs that could be ascribed to the ‘indicative’ CBT interventions for a universal secondary population are presented in Table 19, alongside extrapolated intervention costs for similar interventions in primary and targeted populations. Adding IPT to CBT in a universal secondary population is more costly than CBT alone, driven mainly by additional teacher training and delivery to smaller groups of students. Although the estimated SMD shows a bigger reduction in depression score, compared with usual curriculum, than for CBT alone, the estimate is very uncertain. There is no evidence for the effect of CBT + IPT on anxiety in the universal secondary population. Further evidence on the relative efficacy of CBT and CBT + IPT would be required to justify the additional intervention cost. No studies used a usual curriculum control in either secondary or primary targeted populations. There is some evidence that CBT is effective compared with a waiting list for reducing anxiety in a targeted primary population, but this difference may not extend to comparisons with usual curriculum.

In Table 20, we report the intervention costs and consequences (SMD) for CBT with or without a psychoeducation component in a universal secondary population. Because all of the CBT interventions in the NMA for this population contained cognitive and behavioural components, the comparison is between CBT with just cognitive and behavioural components and CBT with cognitive, behavioural and psychoeducation components. We give results for both anxiety and depression outcomes, although the NMA results only show evidence of a difference for the anxiety outcome. We also report estimated intervention costs, based on our microcosting of typical interventions with these components as described in the RCTs. Adding a psychoeducation component increases intervention costs, but there is evidence that anxiety symptom scores improve post intervention.

Discussion

Review of previous economic studies

The body of evidence described in this review is both small and heterogeneous. Conditions being targeted, interventions and cost-effectiveness analyses were all variable. It was, therefore, not possible to synthesise the results numerically. Multiple perspectives for the analyses were taken, leading to the resources included in the analyses varying widely. The potential long-term costs associated with missing school15,16 (such as lifetime earning capacity) were not estimated in any of the studies. All included studies appropriately compared the intervention with usual provision, or with no intervention (i.e. the model-based studies). Although an active control comparator is appropriate (and necessary) for investigating effectiveness mechanisms, economic analyses are most informative for decision-makers when compared with usual care/curriculum. The two model-based analyses suggested that hypothetical interventions could be cost-effective in the Australian context. However, the trial-based analyses suggested that the interventions were unlikely to be cost-effective in the UK or the USA. For the one intervention that was considered potentially cost-effective in a high-risk subgroup at an interim point of the study, the effect disappeared with longer-term follow-up. There was little empirical costing evidence to inform decisions on the implementation of preventative interventions.

Cost–consequences analysis

The figures used to obtain intervention costs were based on a highly stylised, ‘indicative’ universal intervention that was assumed to be delivered as specified, and there are many ways in which differences might occur in the real world. Although it was assumed that there would be no room hire costs if the intervention were delivered on school premises, there could be heating, lighting or security overheads if the intervention were delivered outside school hours. It is possible that a project manager or administrator would be required to oversee the intervention if it were rolled out across the country. The salary of the teacher delivering the intervention could vary according to experience. Delivery by a psychologist instead of a teacher would affect the salary costs, and psychologists additionally undergo supervision meetings as part of their professional conduct. The intervention would be more costly if two individuals led it instead of one. The detailed intervention cost breakdown by Stallard et al.262 illustrated the variability in individual components that go into making up an intervention, with small changes in delivery method (e.g. the requirement for travel) leading to big differences in costs between methods. Stallard et al.’s262 work suggested that it is a fallacy to assume that delivery by schoolteachers is less costly than delivery by health-care specialists. None of the interventions described here explicitly mentioned a licence fee, and potential administration costs have not been considered. Deriving a value for the opportunity cost of time diverted from other learning activities in school is currently considered problematic and has not been taken into account here. Despite these caveats, this simplistic model serves to give an idea of the costs that might accrue to a school budget in the first year of implementation. Subsequent years would incur lower training outlay, assuming that the same teachers deliver the course. The limited details of interventions described in the published reports meant that it was challenging to assign accurate proportions to psychoeducation components.

Implementation might be more attractive if it could be demonstrated that the intervention has a positive effect on educational outcomes or reduces the need to pay for educational psychologists in the future. However, the systematic review found that few studies of effectiveness had considered educational attainment outcomes (see Chapter 6). Future work should consider developing methodologies for evaluating both effectiveness and cost-effectiveness in terms of school outcomes, as well as the outcomes more typically encountered in health-care studies.

The cost–consequence analysis was based only on the intervention costs (i.e. the effect on health-care use was not addressed). It is worth noting that the beneficial effects of an intervention that aims to prevent or reduce symptoms of anxiety may also extend to reducing depression, and vice versa, which would increase the value of such an intervention. A comparison of costs and standardised outcomes in a cost–consequence analysis is difficult to interpret; ideally, a full cost-effectiveness analysis based on a recognised clinical outcome would be conducted. However, we did not find sufficient evidence for the efficacy of these interventions at 6 months’ post-intervention (and longer) follow-up for the development of a cost-effectiveness model to be useful at the present time. An economic model needs to capture long-term costs and benefits, which may be substantial, as issues with mental health and conduct disorder during school years have been shown to be associated with a range of health and behavioural problems as adults,4 which are costly to society.265 However, further research is needed to develop and evaluate effective interventions for the prevention of mental health and conduct disorders in school-age children before the longer-term consequences of such interventions can be fully assessed.

To ensure high-quality information for decision-makers, it is imperative that future reports of school-based interventions to prevent anxiety, depression or conduct disorder are described in some detail and that the cost implications of interventions are adequately measured.