Background
Attention-Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder, affecting 3–7% of children and adults worldwide [
1‐
4]. Besides the core behavioural symptoms of inattention, hyperactivity and impulsivity [
5], the definition of ADHD includes related interference with social, educational or occupational functioning, and an associated reduced quality of life across the lifespan [
6‐
10]. Neurodevelopmental and psychiatric comorbidity is common in ADHD [
11], further contributing to functional impairment [
12]. Interestingly, ADHD has also been reported to include specific strengths, such as creativity, hyper-focusing and high levels of energy [
13], although these have not been consistently supported by other research findings [
14,
15]. While ADHD typically causes impairment across different life domains, the degree and profile of its individual impact might differ significantly. Therefore, the availability of internationally accepted, standardized classification tools for individual assessment of functional ability and disability in those living with ADHD may be helpful in clinical, research and health care administration settings.
In 2001, the World Health Organization (WHO) released the International Classification of Functioning, Disability and Health (ICF) with the aim to provide a comprehensive and universal framework to describe different aspects of functioning and disability for all health-related conditions [
16]. In 2007, the Children and Youth version of the ICF, the ICF(-CY), was published, designed specifically to capture the functional abilities and disabilities in developing individuals, by adding and expanding on the categories of existing ICF categories [
17]. The ICF(-CY) was designed to complement the International Classification of Diseases-Tenth Version (ICD-10), which defines and describes health conditions, symptoms, complaints, and where possible, causes of injury or diseases [
18]. The ICF(-CY) is based on a bio-psycho-social model of functioning, which conceptualizes disability and ability as the result of an interaction between a health condition with individual physical and personal characteristics, and environmental factors. The ICF(-CY) provides detailed classifications of functioning and disability in the areas of body functions (i.e. physiological functions of body systems), body structures (i.e. anatomical parts of the body), activities (i.e. execution of tasks), participation (i.e. involvement in life situations), and environment (i.e. physical, social and attitudinal environment) [
16]. For each of these components, aspects of functioning can be described at different levels of depths. The first level includes chapters giving an overview of the areas of functioning covered by the nomenclature. These chapters in turn comprise information about specific categories of functioning that are hierarchically structured with up to three level of increasing detail, as demonstrated by the following example from the activity and participation component:
-
Level 1 chapter: d5 self-care
-
Level 2 category: d570 looking after one’s health
-
Level 3 category: d5702 maintaining one’s health
-
Level 4 category: d57022 avoiding risks of abuse of drugs or alcohol
Personal factors, such as gender, race, educational level, coping styles, are also deemed highly important and are included in the framework of the ICF(-CY). However, given their significant social and cultural variability, they have not been classified in the ICF(-CY).
The ICF(-CY), which includes all ICF categories plus additional ones for youth, consists of 1685 categories (Body functions,
k = 531; Body structures,
k = 329; Activities and participation,
k = 552; and Environmental factors,
k = 273). They serve to fine-map functioning and disability in all health conditions in research, clinical and healthcare administration settings for diagnostic, treatment, documentation and reimbursement purposes [
19,
20]. However, even though the comprehensiveness of the ICF(-CY) is an advantage, to use all its categories to describe a specific health condition is both unnecessary and impractical, as many categories may be irrelevant to specific disorders. To address this issue, the development of ICF(-CY) Core Sets was initiated, which involves a rigorous and systematic scientific approach to select ICF(-CY) categories that are most relevant to individuals with a particular health condition. The development of Core Sets comprises a qualitative study (current study), a literature review (“research perspective”), an expert survey (“expert perspective”) and a clinical study (“clinical perspective”). Each study aims to capture general and unique features of functioning and disability related to a specific health condition, ensuring that the process includes a diverse range of professionals and stakeholders across all of the six WHO regions. Therefore, the current study is part of a larger systematic effort that will conclude with the creation of standardized ICF(-CY) Core Sets for ADHD. ICF(-CY) Core Sets for Autism Spectrum Disorder (ASD) are also being developed as part of this project with the results reported in separate publications [
21‐
23]. A general description of the ADHD ICF(-CY) Core Sets development process has been published in a previous issue of this journal [
24].
The objective of this study was to capture the perspectives pertaining to ADHD, as expressed by stakeholders from various WHO-regions, and link them to ICF(-CY) categories. To facilitate comparison with our other ADHD Core Set preparatory studies [
13,
35], an exploratory secondary objective was added to determine the consistency of identified ICF(-CY) concepts. For this purpose, a qualitative and mixed methodology study as outlined by the WHO [
25] was conducted. It involved focus group discussions and individual semi-structured interviews with participants across ages diagnosed with ADHD, self-advocates, immediate family members and professional caregivers, regarding functional disability and ability characteristics of ADHD, as well as facilitators and barriers to functioning. Together with the other preparatory research mentioned above, this study will provide the basis for an international ICF(-CY) Core Sets consensus conference, during which a group of independent ADHD experts, representing different professions and all WHO-regions, will follow a formal decision-making process on which ICF(-CY) categories to be included in the ICF(-CY) Core Sets for ADHD.
Discussion
In preparation for official WHO ICF(-CY) Core Sets for ADHD, the current international qualitative study aimed to investigate the experiences and perspectives of individuals with ADHD, self-advocates, immediate family members and professional caregivers on disability and abilities pertinent to ADHD, as well as facilitators and barriers to functioning. Categories were identified in all four ICF(-CY) components, mainly from activities and participation, but also several environmental factors and body functions. Very few body structures were considered to be relevant. The activities and participation component and environmental factors were described comprehensively, as evidenced by the fact that categories were covered in all nine, respectively, five chapters. In the body functions component, many different aspects of mental functions were considered to be important. Additionally, our study identified evidence of strengths associated with ADHD, such as high level of energy, creativity, hyper-focus, agreeableness, and willingness to assist others.
The large number of ICF-(CY) categories identified across all of the components supports the notion that ADHD impacts on broad areas of body functioning and everyday life adaptive skills. Nearly 70% of all body functions categories covered in this study were from the b1 mental functions chapter, which is consistent with ADHD being conceptualized as neurodevelopmental and behavioural disorder. A total of 16 different mental functions were identified in this study, which demonstrates that cognitive functions are deemed crucial in ADHD. Our study also revealed physical alterations (e.g. body coordination) and sensory issues (e.g. sensation of pain) to be related to ADHD. The impact of ADHD on everyday life was described comprehensively. Consistent with previous studies on ADHD and social functioning [
8,
36], this study identified five aspects of social interactions and relationships to be affected by ADHD. Examples include family relationships and informal social relationships, such as creating and maintaining interactions with friends and peers. Furthermore, ADHD was described to impact formal relationships, such as relating with persons in authority. Engagement in recreation and leisure activities, including participating in social events, were captured in this study as well. In line with previous research on ADHD and its impact on academic achievement [
6], school disabilities were identified in this study. Other activities related to school, such as undertaking tasks and maintaining attention on homework assignments, were mentioned to be affected by ADHD too. Although occupational functioning was not covered in this study, some participants described having supportive individuals in the work environment that helped them with their tasks. These include people in positions of authority (e.g. employers) and colleagues. Their attitudes towards individuals with ADHD were also described to be positive, which made it easier to meet deadline dates and complete required work assignments. The categories in the environmental factors component can either functionally be perceived as a barrier or facilitator by the individual. For example, medication (i.e. e110 products or substances for personal consumption) might be experienced both in terms of relief from core symptoms of ADHD, but also generating functional challenges (e.g. sleep problems) owing to side effects. Compared to the other ICF(-CY) components, body structures were less commonly identified. Structure of brain was pointed-out as correlate of the many mental functions that were reported in this study. Interestingly, although not formally linkable to ICF(-CY) categories, a large number of personal factors was identified in this study, indicating that individual personal characteristics and resources are pivotal for handling of ADHD. The latter data combined with the results from the other three preparatory studies [
13,
24,
35] on personal factors provide an additional valuable future option to analyse the data set in terms of overarching personal factors relevant to the management of ADHD.
Contrary to our other preparatory studies, published in previous issues of this journal [
13,
35], this qualitative study did not capture any aspect related to occupational functioning. The current study did, however, identify a wider range of environmental factors relevant to ADHD, compared to the earlier ones. This suggests that environmental factors are considered more important for functioning in ADHD by subjects diagnosed with the condition, their immediate family members and professional caregivers than the current research literature indicates and ADHD experts suggest. Recurring themes that were identified in this study, such as attention, psychomotor functions, recreation and leisure, complex interpersonal interactions and immediate family, were also found to be relevant in the literature review [
35] and expert survey [
13].
This study is amongst the first to explore specific strengths in ADHD from an international and first hand perspective. Overall, the opinions stated were rather broad and not straightforward. In addition, several participants felt unable to mention any positive aspects related to ADHD, even when explicitly prompted. The most recurring themes about positive sides were creativity, high energy level, hyper-focus and sympathetic personality traits such as agreeableness and empathy. Still, there is currently little or no empirical support for such strengths outside of this study [
14,
15]. However, importantly, these positive aspects were also identified in our earlier international expert survey, which included 174 experienced ADHD scientists and clinicians from 11 different professional backgrounds and 45 countries [
13]. Thus, in combination with results from the other preparatory studies, well-grounded novel hypotheses for future research can be generated within this area of topic.
The current study presents with some methodological challenges. The generalizability of the consistency of recurring ICF(-CY) categories across groups might be questioned, as the analyses were based on uneven sample sizes and compositions, i.e. half of the stakeholder groups came from Sweden and not all were equally represented. However, these orienting frequency analyses only reflect the consistency of ICF(-CY) categories across groups and were mainly conducted to facilitate comparisons with the other two previous preparatory studies [
13,
35]. The primary aim of this study was to capture the experiences of health-related functioning in ADHD by involving a diverse range of stakeholders and WHO-regions, and our saturation analyses showed that identified categories were probably quite exhaustive for ADHD in general. The involvement of several culturally diverse countries also generated challenges concerning transcriptions to English. Proper translation of specific cultural expressions and their exact connotation can be difficult or even impossible. In cases where an English equivalent was missing, similar terms were used. While the linking was conducted in collaboration with researcher located at one center for reasons of standardization and practicability, future studies might consider using independent researchers doing directly the linking of ICF(-CY) categories in their native language. Another possible weakness of this study is the non-involvement of business colleagues or employers of individuals with ADHD in the focus group discussions and individual interviews. Work is an important arena for individuals with ADHD and some functional abilities and disabilities might only be observable in work settings and perceived by colleagues or employers. However, there are given ethical and practical challenges to involve these groups in research. One challenge the current study faced was to adapt the focus group and interview items to the different age groups of individuals with ADHD. Some children and young adolescents found the questions rather difficult to discuss. Examples were given to clarify each of the questions, but in some cases it was still difficult for the younger participants to respond.
Despite the limitations, this study managed to identify a wide range of functional abilities and disabilities in individuals with ADHD by involving multiple stakeholders and WHO-regions. Compared to previous ICF qualitative studies [
27‐
29], this study had a very heterogeneous and international sample of participants. The involvement of primary informants, namely diagnosed individuals, provides researchers with unique insights into how ADHD impacts various areas of daily life functioning. It offers, more importantly, individuals diagnosed with ADHD and their family members a chance to share their experiences and listen to other participants’ stories. The inclusion of diagnosed individuals and their caregivers in the Core Sets development has purposely been designed by the WHO and ICF Research Branch to involve a wide range of stakeholders. The four studies will together provide the basis for the ICF consensus conference, in which the first version of ICF(-CY) Core Sets for ADHD will be determined. The results of the first two preparatory studies, namely the comprehensive scoping review and expert survey, have already been published in previous issues of this journal [
13,
35]. The remaining preparatory study of the ICF(-CY) Core Sets for ADHD project is a clinical cross-sectional investigation, with the objective to capture functional disability and strength in actual patients in naturalistic clinical settings. For the clinical study, participants will be recruited from clinics all over the world, thus making it possible to capture aspects of functioning and disability that might have been overlooked in this or previous studies or are specific to clinical environments. Once the first version of the ICF(-CY) Core Sets for ADHD has been defined, meaningful tools (e.g. diagnostic instruments, observation schedules, interviews) can be derived, psychometrically evaluated and used by stakeholders in different settings (e.g. research, clinical practice, health care administration and policy makers). Their implementation can aid to assess functioning and disability in individuals with ADHD, tailor treatment plans, follow-up intervention effects, and calculate related treatment resources.
Acknowledgements
The development of the ICF(-CY) Core Sets for ADHD is a cooperative effort of the WHO, the ICF Research Branch, a partner of the WHO Collaboration Centre for the Family of International Classifications in Germany (at DIMDI), the European Network of Hyperkinetic Disorders (EUNETHYDIS), and the Center of Neurodevelopmental Disorders at the Karolinska Institutet (KIND) in Sweden. Guidance on this project is provided by a Steering Committee comprised of key opinion leaders in the field of ADHD from all six WHO regions. The development of ICF(-CY) Core Sets for ADHD is supported by the Swedish Research Council (grant. nr. 523-2009-7054), and the Swedish Research Council in partnership with FAS (now renamed FORTE), FORMAS and VINNOVA (trans-disciplinary research programmes on child and youth mental health, grant nr. 259-2012-24). This study also acknowledges the assistance of independent researchers and clinicians who conducted or analysed data from focus group discussions and semi-structured interviews. These include Norah Alissa (King Abdulaziz Medical City –National Guard Hospital), Hind Alrashoud (King Abdulaziz Medical City –National Guard Hospital), Anna Borg (Karolinska Institutet; KIND), Andreas Fällman (Karolinska Institutet; KIND), Anders Görling (Karolinska Institutet; KIND), Joy Hättestrand (Karolinska Institutet; KIND), Anna Pilfalk (Karolinska Institutet; KIND), James Shelly (University of Cape Town) and Eric Zander (Karolinska Institutet; KIND).
Compliance with ethical standards