Effectiveness and cost-effectiveness of interventions to increase knowledge and awareness of attention deficit hyperactivity disorder: a systematic review

The search strategy was developed by the primary reviewer (KM) through a preliminary search and consultation with the review team and a librarian. A comprehensive search was conducted in EBSCOhost databases (MEDLINE Complete, APA PsycInfo, CINAHL Complete, ERIC, Global Health and EconLit) to search for literature published until 8th August 2023 and updated on 16th February 2024. Multiple search terms were used for three concepts: (1) attention-deficit/hyperactivity disorder, (2) economic evaluation, (3) intervention and awareness (Appendix A). A Google Scholar search was also conducted to identify any relevant studies (Appendix A).

Studies were included if they were (1) peer-reviewed publications in English, (2) explored the effectiveness or cost-effectiveness of interventions for ADHD awareness and knowledge for caregivers, clinicians, or teachers, (3) primary quantitative studies. Studies on intervention effectiveness were included if the primary outcome measured was awareness, knowledge or evidence-based practices outcomes. Due to limited economic evaluation literature, we included interventions with educational/knowledge components, but with any outcome measure (not restricted to measuring awareness/knowledge changes). Studies were excluded if they (1) did not meet the above criteria, (2) only used qualitative data collection methods or were a secondary study (review). Secondary studies (i.e., reviews) identified from the search were hand-searched to exclude any primary effectiveness studies included in those reviews to avoid repeating results.

All studies retrieved from the search were exported to Endnote [25] and then imported into Covidence [26]. A pilot screening was conducted with a random sample of one hundred studies to ensure agreement of the inclusion criteria. The studies were screened independently by two reviewers (KM and SWAD) through a two-stage process: (1) title and abstract and (2) full-text. Any disagreement among the two reviewers was discussed until a consensus was reached, with resolution through a third reviewer (HL or TS) if necessary. The primary reviewer completed the data extraction, which was cross-checked by the second reviewer. For effectiveness studies, the extracted information described the author, year, country, study design, target population and sample, ADHD status, intervention type and description, assessment tools, primary outcome, and results. For studies reporting cost or cost-effectiveness, additional data were extracted on study perspective, cost year, time horizon, and discount rate.

The methodological quality of the included studies was independently assessed by the two reviewers using (1) The National Heart, Lung, and Blood Institute (NHLBI) quality assessment tools [27] for Controlled Intervention Studies, Before-After (Pre-Post) Studies With No Control Group, and Observational Cohort and Cross-Sectional Studies, because of its rigorous criteria, allowing a consistent assessment of various study designs [27] and its wide use [28‐32], (2) Mixed Methods Appraisal Tool [33] for Quantitative non-randomized studies (pre-post with non-randomized control group), as NHLBI tool for controlled studies primarily focuses on randomized controls, whereas the MMAT provides criteria for evaluating non-randomized studies [33] and (3) Drummond’s checklist for economic evaluation studies [34]. The description of each tool and the applicable questions used are outlined in Appendix B, and the scoring technique and quality assessment results tables are described in Appendix C. Disagreements were resolved through discussion until a consensus was reached.

A narrative synthesis approach was used to synthesize study findings [35‐37] whereby study characteristics were tabulated and studies were subgrouped by the intervention target population (i.e., caregivers, clinicians, teachers) and the primary outcomes measured; the findings were synthesized through the frequency and type of outcomes reported [35]. A meta-analysis was not conducted due to the heterogeneity among the studies’ methodology and outcome measures. When reporting the findings from the economic studies, all costs were converted into 2024 purchasing power parity (PPP) estimates (international dollars) using a standard conversion tool [38] to allow comparability across countries [39].

The database search yielded 5963 studies, of which 24 were included in the analysis. Google Scholar search identified a further four studies, resulting in 28 studies included in the analysis. The updated search found no further studies to be included (Fig. 1). There was an inter-rater agreement of 85% among the two reviewers for the full-text screening. Included studies (n = 28) represented a wide range of countries; fifteen studies from North America [United States (n = 14) and Canada (n = 1)], eight from Europe [United Kingdom (n = 5), Greece (n = 1), Spain (n = 1), Sweden (n = 1),], two from Asia [India (n = 1), Saudi Arabia (n = 1)], two from Africa [Egypt (n = 2)], and one from Oceania [Australia (n = 1)] (Table 1). Twenty-four studies evaluated or reported the effectiveness of an intervention, of which nine utilized a randomized control trial design, three used a quantitative non-randomized design (pre/post-test) with control group, thirteen studies were a before-after (pre-post) with no control group design, and one was a cross-sectional study. The four economic studies were cost-effectiveness analyses.

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Of the 22 studies that were assessed using the NHLBI checklists [27], most (59%) were rated as fair quality, and almost one third (27%) were rated as poor quality. Of the two studies that were assessed using the Mixed Methods Appraisal Tool [33], one was rated as high, and one as medium quality. The difference in quality ratings between the tools may be explained by the focus of the NHLBI critical appraisal on the internal validity of a study, whereby risk of bias due to methodological limitations was frequent: poor reporting of randomization techniques, lack of blinding, and poor reporting of sample size power. Three out of four economic evaluation studies met greater than 75% of quality criteria of Drummond’s 35-item checklist [34], indicating good quality (Appendix C).

The results from this systematic review demonstrate that interventions can be effective in increasing the awareness and knowledge of ADHD among caregivers, clinicians, and teachers. While there was no economic evaluation of interventions with the primary outcome of increasing knowledge, knowledge and skill improvement resulting from these interventions enabled caregivers to manage their child’s ADHD symptoms more positively, such as behavioral management and psychosocial programs. Previous reviews [9, 10] indicate that psychoeducation and other interventions such as behavioral parent training and parent education are effective in increasing awareness and knowledge of ADHD among caregivers. Behavioral management interventions were found to be cost-effective, with costs per participant ranging from $178 to $211 depending on program intensity and delivery format. Similarly, psychosocial programs were also found to be cost effective depending on the delivery mode. Our review contributes to the growing evidence of interventions to increase awareness and knowledge about health conditions [67, 68]. Findings should be interpreted cautiously due to substantial heterogeneity across intervention design, duration, and outcome measurement tools, which may have contributed to various intervention effectiveness and limited cross-study comparability, preventing meta-analysis from being conducted. This heterogeneity made it difficult to draw definitive conclusions about which interventions may be more beneficial, or superior to others in improving ADHD knowledge among caregivers, clinicians, and teachers. Further, we found differences in quality assessment tools whereby the MMAT [33] tended to result in higher quality scores than the NHLBI tools [27]. The difference in overall quality rating between the tools may be explained by the focus of the NHLBI checklists on the internal validity of a study, and whereby the included studies’ risk of bias due to methodological limitations was frequent; poor reporting of randomization techniques, lack of blinding, poor reporting of sample size power and loss to follow-up [37].

The present study’s findings are consistent with the findings from Ward et al. [20] whereby teacher training interventions for ADHD can improve knowledge and positive behaviors toward children with ADHD symptoms. Our review advanced the previous review by including ten studies on other teacher populations, such as graduate and pre-service teachers. Our findings demonstrate that teachers’ knowledge and awareness of ADHD including knowledge and practice of behavioral management skills, and ability to detect ADHD symptoms in children were improved with knowledge training/programs consisting of lectures, webinars and workshops supported by roleplay, discussion, and handouts. While this review found the teacher-focused training interventions are effective, ADHD knowledge among teachers may not have significantly improved over time [7]. There is a need for ongoing teacher training interventions such as the programs discussed in this review, as poor ADHD knowledge is still reported as a key barrier to diagnosing and managing the condition in children [4‐6].

Our review demonstrates that training and educational interventions can be effective in increasing ADHD knowledge among caregivers. Specific knowledge and skill development to inform parents about ADHD and supporting their child is important for improving parental recognition of symptoms, reducing stigma, misconceptions, in turn increasing caregivers’ willingness access and utilize healthcare services [11, 69].

We found that there is little evidence to preference one program over another. For example, a multi-component intervention did not have greater effects than a parent education only program [70], and a group intervention format was not inferior to individual behavioral parenting training (BPT) [71]. It is likely that patient preferences of format (online versus in-person, clinic versus home-based) and the intervention costs are the most prominent factors to consider when delivering interventions [72]. Group-based behavioral parent training has previously been recommended for pre-school aged children [73] as it is equally effective and can be more cost-effective than individual-based training. The common pattern across the heterogeneous interventions is that most have resulted in increases in knowledge and capacity, demonstrating that positive outcomes can be achieved through lower-resource-required interventions such as single or few session webinars, or workshops.

To our knowledge, this is the first review to synthesize evidence on interventions to address clinician ADHD awareness and knowledge. We found that clinician-targeted interventions were received well, with participants highlighting formats as appropriate, resources being useful and addressed ‘some to most’ of general practitioner’s knowledge needs [49, 50]. Depending on intervention types, our review found that clinician awareness and knowledge of ADHD and their self-efficacy in integrating evidence-based ADHD practices for diagnosis and treatment can be effectively increased in the short term through the delivery of a 40-min web-based resource [49], a 1 day course [14], or can be sustained for up to 24 months when the intervention involves continuous quality improvement focused on aligning clinician practices with the American Academy of Pediatrics consensus guideline recommendations [48]. Although clinicians’ and healthcare professionals’ ADHD awareness and knowledge have improved over time, the evolving evidence on diagnosis and treatment approaches requires a frequent update of knowledge, and thus, ongoing interventions would be needed to upskill clinicians in ADHD management, including knowledge of care pathways, diagnosis and treatment [74, 75].

This current review is the first to synthesize economic evidence on interventions that have included an ADHD education component for caregivers and teachers. Whilst none of the interventions directly measured knowledge as a primary outcome, ADHD educational/knowledge component was embedded in the intervention content. Parent and teacher knowledge and skill improvement resulting from these interventions could have enabled caregivers and teachers to support children with ADHD more positively. We found that these interventions led to improved outcomes of averted DALYs and resolved ADHD cases. All these four studies found that interventions with educational components were promising or cost-effective, depending on the intensity and the format/design (Table 2). Behavioral interventions focusing on behavioral management were found to be cost-effective and effective in reducing DALYs [63]. Ongoing economic evaluation of interventions, including for caregivers, clinicians, and teachers is crucial as the information on costs and cost-effectiveness can assist policy-making decisions on population health resources allocation [72].

Lack of ADHD awareness and knowledge among caregivers, clinicians, and teachers have long been key barriers to service access and utilization [4, 6, 76], therefore, promoting these interventions to improve awareness and knowledge of ADHD are important to enable timely access and utilization of services for diagnosis and treatment. We support the recommendation in the Australian clinical guidelines which encourages the provision of education and training to clinicians to improve their knowledge and capacity for evidence-based practices, to reduce stigma and misconceptions that can act as barriers to service utilization [13].

Interventions can demonstrate modest improvements at relatively low cost, or substantial improvements and higher costs, however, the limited economic evidence in our review suggests they offer quite similar overall returns on investment and therefore, all could be considered depending on health system priority areas and available resources/allocated budget.

The scarcity of literature on economic evaluation of ADHD interventions targeted at caregivers, clinicians, and teachers highlights a need for more cost-effectiveness studies of interventions among these populations. Given the high heterogeneity in outcome measures in effectiveness studies, it would be beneficial for future research to explore a common core outcome set that can be applied to all ADHD interventions aiming to improve ADHD awareness/knowledge to enable cross-study outcome comparison.

Restricting the inclusion criteria to peer-reviewed and English language may have resulted in missing unpublished or grey literature, or non-English literature containing evidence on the effectiveness and cost-effectiveness of interventions. Excluding non-English studies could introduce bias omitting studies from regions where interventions may have been evaluated differently. The search term for economic evaluation used for the Google Scholar search was cost-effectiveness, and therefore may have resulted in missing relevant studies. Studies in this review demonstrate a limitation in the lack of consistency across interventions and outcome measures (high heterogeneity) which prevented comparability across studies.