Eur Child Adolesc Psychiatry (2015) 24:859–872 DOI 10.1007/s00787-015-0727-z

REVIEW

A comprehensive scoping review of ability and disability in ADHD using the International Classification of Functioning, Disability and Health‑Children and Youth Version (ICF‑CY) Elles de Schipper1,12 · Aiko Lundequist1,12 · Anna Löfgren Wilteus1,12 · David Coghill2 · Petrus J. de Vries3 · Mats Granlund4 · Martin Holtmann5 · Ulf Jonsson1,12 · Sunil Karande6 · Florence Levy7 · Omar Al‑Modayfer8 · Luis Rohde9 · Rosemary Tannock10 · Bruce Tonge11 · Sven Bölte1,12  Received: 22 December 2014 / Accepted: 18 May 2015 / Published online: 3 June 2015 © Springer-Verlag Berlin Heidelberg 2015

Abstract  This is the first in a series of four empirical investigations to develop International Classification of Functioning, Disability and Health (ICF) Core Sets for Attention Deficit Hyperactivity Disorder (ADHD). The objective here was to use a comprehensive scoping review approach to identify the concepts of functional ability and disability used in the scientific ADHD literature and link these to the nomenclature of the ICF-CY. Systematic searches were conducted using Medline/PubMed, PsycINFO, ERIC and Cinahl, to extract the relevant concepts of functional ability and disability from the identified outcome studies of ADHD. These concepts were then linked to ICF-CY by two independent researchers using a standardized linking procedure. Data from identified studies

Electronic supplementary material  The online version of this article (doi:10.1007/s00787-015-0727-z) contains supplementary material, which is available to authorized users. * Sven Bölte [email protected] 1



Paediatric Neuropsychiatry Unit, Department of Women’s and Children’s Health, Center of Neurodevelopmental Disorders (KIND), Stockholm, Sweden

were analysed until saturation of ICF-CY categories was reached. Eighty studies were included in the final analysis. Concepts contained in these studies were linked to 128 ICF-CY categories. Of these categories, 68 were considered to be particularly relevant to ADHD (i.e., identified in at least 5 % of the studies). Of these, 32 were related to Activities and participation, 31 were related to Body functions, and five were related to environmental factors. The five most frequently identified categories were school education (53 %), energy and drive functions (50 %), psychomotor functions (50 %), attention functions (49 %), and emotional functions (45 %). The broad variety of ICF-CY categories identified in this study underlines the necessity to consider ability and disability in ADHD across all dimensions of life, for which the ICF-CY provides a valuable and universally applicable framework. These results, in combination with three additional preparatory studies 7



School of Psychiatry, Prince of Wales Hospital and University of New South Wales, Sydney, Australia

8



Psychiatry Section, King Abdulaziz Medical City, College of Medicine, Riyadh, Saudi Arabia

9



Department of Psychiatry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil

2

Division of Neuroscience, Ninewells Hospital and Medical School, Medical Research Institute, University of Dundee, Dundee, UK

10

Neurosciences and Mental Health Research Program, The Hospital for Sick Children, University of Toronto, Toronto, Canada

3

Division of Child and Adolescent Psychiatry, University of Cape Town, Cape Town, South Africa

11

Centre for Developmental Psychiatry and Psychology, Monash University, Melbourne, Victoria, Australia

4

CHILD, Jönköping University, Jönköping, Sweden

12

5

LWL-University Hospital for Child and Adolescent Psychiatry, Psychotherapy and Psychosomatics of the Ruhr University Bochum, Hamm, Germany

Center for Psychiatry Research, Child and Adolescent Psychiatry, Stockholm County Council, Stockholm, Sweden

6

Department of Paediatrics, Learning Disability Clinic, Seth G.S. Medical College and K.E.M. Hospital, Mumbai, India







13

860

(expert survey, focus groups, clinical study), will provide a scientific basis to define the ICF Core Sets for ADHD for multi-purpose use in basic and applied research, and every day clinical practice. Keywords  Neurodevelopmental disorder · Assessment · Child psychiatry · Diagnostics · ICD · DSM

Background Attention deficit hyperactivity disorder (ADHD) is one of the most commonly diagnosed neurodevelopmental disorders in childhood, affecting approximately 5 % of schoolaged children worldwide [1, 2], and continues into adulthood, with an estimated prevalence of 2.5 % [3]. Apart from the core symptom domains (i.e., inattention, hyperactivity, and impulsivity), ADHD is associated with increased risk of social and emotional limitations, educational and occupational restrictions, health-related impairments and psychiatric comorbidities [4, 5], often resulting in reduced quality of life [6, 7]. In a recent review of the literature, Shaw and colleagues [8] studied long-term outcomes in ADHD and found that, even when treated, affected individuals showed poorer outcomes in major life areas, including education, occupation, and social participation. Üstün [9] argued for targeting improved disability management and prevention in ADHD, and stressed the need for a broad focus on both core symptoms and related disabilities in research and clinical practice. With the International Classification of Functioning, Disability and Health (ICF) [10], developed by the World Health Organization (WHO), a comprehensive framework exists to realize this aim. The ICF is an interactive bio-psycho-social model of functioning, disability and health, which incorporates various factors in the areas of body functions (physiological functions of body systems), Body structures (anatomical parts of the body), Activities (execution of a task or action), Participation (involvement in a life situation), and Environmental factors (physical, social and attitudinal environment) to explain functioning in individuals with a particular health condition across all major life areas and in the context of the environment. The ICF constitutes a collection of categories describing aspects of functioning in these areas. It was developed to provide a universally accepted framework for the description of health and functioning, permitting communication about health and health care across the world in various disciplines and sciences [10]. The biopsychosocial model also includes Personal factors (features of the individual that make up the particular background of an individual’s life and living, and are not part of a health condition), but to date, these have not yet been systematized within the ICF, and their use in the classification of

13

Eur Child Adolesc Psychiatry (2015) 24:859–872

functioning is subject of ongoing debate [11, 12]. To capture functional abilities and disabilities in developing individuals, a children and youth version was derived from the ICF (ICF-CY) [13] by adding to and expanding upon the descriptions of existing ICF categories. The ICF and ICF-CY [referred to below as “ICF(-CY)”] provide methods for classifying functioning within four key components of the bio-psycho-social model, i.e., Body functions, Body structures, Activities and Participation, and Environmental factors. For each of these components, aspects of functioning are described in hierarchically structured categories with up to four levels of increasing detail. At the first level are superordinate categories, referred to as ‘chapters’, which provide a general overview of the areas of functioning that are covered by the ICF(-CY). The chapters consist of second, third and fourth level ‘categories’, as shown in the following example of an ADHD-relevant classification from the Activities 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: d57020 Managing medications and following health advice.

In its current form, with over 1400 categories, the full version of the ICF(-CY) is difficult to implement in the daily practice of clinicians and researchers alike. ICF Core Sets (selections of ICF(-CY) categories that are considered most relevant to individuals with a particular health condition [14–16]) are viewed as an effective way to facilitate and promote the implementation of the ICF(-CY) in the scientific study and clinical treatment of individuals with health conditions. ICF Core Sets serve as guidelines to measurement when trying to gain a comprehensive assessment of both ability and disability in individuals with a specific health condition. In clinical practice, they are useful in the assessment of client functioning and treatment evaluation, while in scientific research, they provide a basis for designing studies and for the development of assessment tools. To date, ICF Core Sets have been developed mostly for physical health conditions, such as spinal cord injury [17, 18], diabetes mellitus [19], and breast cancer [20]. Various efforts have been made to implement the ICF(-CY) in mental health, such as by using the ICF(-CY) to analyse the content of existing measures [21–23], developing and validating ICF(-CY) based measures [24–26], and identifying selections of ICF(-CY) categories relevant for certain mental health conditions (i.e., affective, somatoform, anxiety and adjustment disorders [27] and autism spectrum disorder [28]). Only two ICF Core Sets have so far been developed for mental health conditions, namely depression

Eur Child Adolesc Psychiatry (2015) 24:859–872

[29] and bipolar disorder [30]. Üstün [9] suggested that the development of a specific core set for ADHD would be a milestone that will facilitate the use of the ICF(-CY) classification in ADHD research and clinical practice. A core set for adults with ADHD was recently developed in Sweden using a Delphi exercise and a consensus conference [31]. The authors identified 66 ICF categories that cover a wide range of functions from the Body functions, Activities and Participation, and the Environmental factors components. In contrast to the traditional approach to development of ICF Core Sets that follows a rigorous process, which includes several empirical studies conducted across the world, this Swedish core set was based on a single preparatory study that only included Swedish experts. Thus, as acknowledged by the authors themselves, this core set must be viewed as culture-specific and preliminary. The current study is the first part of a comprehensive programme that will develop robust ICF Core Sets for ADHD. It follows the rigorous scientific protocol proposed by the WHO and the ICF Research Branch in collaboration with the WHO Collaborating Centre for the family of International Classifications in Germany (at DIMDI) and includes multiple empirical studies and international perspectives. Also, it aims to capture both ability and disability in individuals with ADHD across the lifespan and uses the ICF-CY (including all general ICF categories plus those more specific to childhood and adolescence). Possible abilities related to ADHD (e.g., hyper focusing, creativity, high levels of energy, flexibility) have not been a priority of ADHD research to date. However, getting a grasp on specific strengths related to ADHD is certainly valuable for the organisation of support that builds on clients’ strengths. Ability and disability are of equal importance in the ICFCY. For this reason, one of the specific aims of the Core Sets development is to identify and include ICF-CY categories that represent abilities related to ADHD. The present study is the first empirical component in a series of four that are part of this comprehensive development process. This first study entails a comprehensive scoping literature review with the objective to capture the “research perspective” on which aspects of ability and disability are characteristic in individuals with ADHD, and to begin the process of reducing the total number of ICF-CY categories and focusing down on those that are considered important from a research perspective (in essence we used a systematic approach to identify the ‘high frequency’ categories, with ‘high’ defined as present in >5 % of studies). Three additional studies resulting in similar selections of ICF-CY categories from different perspectives (expert survey capturing “opinion leader perspective”; focus groups capturing “client and other perspective”; empirical cross-sectional study capturing “clinician perspective”) will be carried out as part of the overall process [23]. Together with results from these complementary

861

studies, the results from this study will provide content for an international consensus conference, in which a group of ADHD experts from all WHO regions will follow a formal decision-making process to arrive at a consensus on the ICFCY categories to be included in the ICF Core Sets for ADHD. The complete development process has been described in more detail in a previous publication [32].

Methods This comprehensive scoping review followed the principles outlined by the World Health Organization (WHO) and the ICF Research Branch for the development of ICF Core Sets [16]. These principles have previously been applied in the development of International Classification of Functioning, Disability and Health (ICF) Core Sets for several neurological and psychiatric disorders, such as cerebral palsy [33], spinal cord injury [34], bipolar disorder [35], and depressive disorder [36]. The approach can be summarized in four (practical) steps: (1) identify studies that focus on functioning in ADHD, (2) identify instruments and parameters used in these studies to define and measure functioning in ADHD, (3) identify meaningful concepts representing aspects of functioning contained in these instruments and parameters, and (4) link these meaningful concepts to corresponding ICF-CY categories. Below, we describe in detail how each of these steps was carried out in this study. Identify studies that focus on functioning in ADHD To identify as many relevant studies as possible, creating a broad representation of what might be considered relevant to functioning in ADHD, a comprehensive systematic search was applied to the electronic databases Medline/PubMed, PsycINFO, ERIC, and Cinahl. The search was performed in two steps: first, free text terms for ADHD and related functional outcomes were selected. These included terms commonly used to describe ADHD, such as “attention deficit hyperactivity disorder”, “hyperkinetic disorder” and “hyperkinesis”, and terms describing various aspects of functioning that have been studied in relation to ADHD or that are used in the ICF terminology, including “peer relationships”, “quality of life”, “participation” and “functional impairment”. These terms were based on previous ICF research and systematic reviews of functioning or ADHD. Second, controlled vocabulary (e.g., MeSH terms, Index terms) was selected to cover the free text terms that were selected in step one. An optimization of the search strategy was conducted by a librarian at the Karolinska Institutet University Library. Each of the four databases was examined first with the controlled vocabulary to identify relevant studies from the indexed articles. Thereafter, PubMed was searched with

13

862

Eur Child Adolesc Psychiatry (2015) 24:859–872

the free text terms to identify the most recent relevant articles that had not yet been indexed (previous year only). All searches were automatically limited to journal articles that included abstracts, written in English, and involved human study populations. The search was run on September 3, 2013. The full search strategy can be found in Appendix 1. The abstracts of papers identified in the search were screened for inclusion in further analysis. As in the search strategy, eligibility criteria were chosen that would facilitate a broad representation of functioning in ADHD:

Meaningful concepts are concise descriptions of specific behaviours, skills or other aspects of functioning that are to be linked to ICF-CY categories. Whenever possible, concepts were extracted on the item level, but if items by themselves did not clearly represent a concept of function (e.g., items/tasks in an IQ test), concepts were extracted on a sub-scale or full-scale level.

Types of publication Original journal articles, published in English from 1982 onwards Types of design Studies of any design that present original data (including case studies, but not theoretical studies) Types of population Participants of any age with a primary diagnosis of ADHD according to DSM, ICD, clinical assessment, diagnostic instruments (ADHD—any subtype; ADD; Hyperkinetic Disorder) Types of outcome Any self-report, proxy (e.g., parent-/caregiver-) report or observational/performance data that was measured as a potential functional outcome of ADHD

To translate these results into a list of ICF-CY categories representing the “research perspective”, meaningful concepts identified in the previous step were linked to ICF-CY categories following formalized linking rules and procedures determined by the WHO ICF Research Branch [37, 38]. The linking rules provide guidance not only on how to link concepts to ICF(-CY) categories, but also what to do in cases where it is not possible to link concepts. Specific codes assigned to these concepts are (1) Personal factor, if the concept is not contained in the ICF(-CY), but is clearly a Personal factor as defined in the ICF(-CY); (2) not covered, if the concept is not contained in the ICF(-CY) and also is not a Personal factor; (3) not definable, when the information provided in the concept is not sufficient for assigning it to a specific ICF(-CY) category; and (4) health condition, if the concept refers to a diagnosis or health condition. Given that there are many different ways to describe the same aspect of functioning, it is possible for different meaningful concepts to be assigned to the same ICF(-CY) category. Given that the literature search resulted in a large number of studies (N  = 16,841) which were not feasible to analyse in full, a decision was made to analyse a subset of them. This approach follows the guidelines for ICF Core Sets development for situations where the initial search yields a large number of studies [16]. To determine the sample size required to generate a valid representation of the “research perspective”, it was decided to analyse data from identified studies until the point of saturation (i.e., when further analysis does not yield new information). Saturation is applied if a given data set is extremely large and there is a high likelihood that analysing all is repetitive and superfluous. The concept of data saturation is a well-established element in qualitative research and has been shown to yield results that are comparable to those achieved by analysis of all available data [39], but there are no defined criteria to determine when saturation is reached, and some authors argue that saturation is ultimately unable to prove in itself that it leads to exhaustive results [40]. However, regarding the latter, the current study did not aim for completeness of ICF(-CY) categories examined in research, but rather to identify the most important ones only. Thus, the

Identify instruments and parameters used in these studies to define and measure functioning in ADHD Where the screening of abstracts did not provide enough information to include or exclude a study, the full texts were screened and a decision about eligibility was made in this step. All included studies were analysed in detail and information was extracted from them. For descriptive purposes, information was recorded about the characteristics of the study participants (including age, gender, diagnosis, WHO region where they were recruited) and the type of study (observational, intervention, control group, type of intervention). For the main goal of this study, instruments and parameters used were recorded according to the following principle: every instrument (standardized and non-standardized measure of functioning, disability and quality of life) or parameter that was defined as an outcome of ADHD in the study was included. Instruments that were used to determine the diagnosis or other criteria relevant for participant inclusion in the study were not recorded. As we wanted to create a broad and unbiased representation of possible ICF-CY categories to form the basis for the Core Sets, no further restrictions as to which measures should be included were implemented. Identify meaningful concepts representing the aspects of functioning covered by these instruments and parameters All identified instruments and parameters were analysed to identify the meaningful concepts contained in them.

13

Link meaningful concepts to corresponding ICF‑CY categories

Eur Child Adolesc Psychiatry (2015) 24:859–872

863

Fig. 1  Schematic presentation of saturation method

saturation approach seems appropriate here. In this study, the concept of saturation was adopted and integrated to fit a more quantitative methodology. Smaller samples of studies were analysed consecutively and, in keeping with procedures used in previous Core Set studies, saturation of data was defined as the point during data analysis at which the linking of concepts of two consecutive samples each revealed no more than 5 % new ICF-CY categories in relation to the number of categories already identified [41, 42]. In effect, this meant that samples of studies drawn from the total sample were analysed following the steps described above. After completing the analysis of each sample, the ICF-CY categories identified in that sample were compared to those identified in samples analysed up to that point. As soon as the analysis of two consecutive samples, each resulted in less than 5 % new ICF-CY categories; it was determined that saturation of data was reached and data analysis concluded. See Fig. 1 for a schematic presentation of the saturation method. The development of ICF Core Sets for ADHD, including this comprehensive scoping literature review, is conducted under the guidance of an international Steering Committee (SC), representing ADHD opinion leaders from all six WHO regions. Specifically, the SC was involved in decisions made regarding the procedure followed in this study. SC members were asked to provide input on the search strategy and eligibility criteria for included studies. When the search yielded a large number of studies, the SC facilitated the necessary additional decisions to restrict the number of studies from the search by sampling of studies and analysing until ICF-CY category identification saturation.

In addition, SC members were requested to provide information on studies considered to be landmarks in investigating functioning in ADHD (e.g., intervention, quality of life, observation studies) for inclusion in the review to represent the “research perspective” comprehensively. SC members provided 55 landmark studies (referred to as the “positive list”—see appendix 2) that were used for three purposes. First, the “positive list” was used to determine a relevant publication time frame for the literature search (i.e., the search range was set to include the publication date of the oldest study on the “positive list”). Second, the “positive list” was used to check the validity of the literature search (i.e., the search results should include all studies on the “positive list”). Third, the “positive list” served as the first sample to be analysed in the saturation procedure, which ensured that all landmark studies were included in the analysis. Thereafter, computer-generated random samples of 100 studies each were analysed until saturation was reached (see Fig. 1). In the interest of quality assurance, each of the four steps described above was carried out by two independent researchers (either ES and ALW or ES and AL). After each step, results were compared and consensus discussions were used to resolve disagreements (see Fig. 1). In the case that consensus could not be reached in these discussions, there was the possibility of consulting a third researcher to make the final decision. However, this possibility was never used because all disagreements were resolved by discussion between the two researchers. To evaluate initial agreement between the two researchers (prior to consensus in case of disagreement) for the linking process, the

13

864

overall percentage of agreement was calculated. For ES and ALW, this was 72 % for the 2nd-level ICF-CY categories and 76 % at the level of ICF-CY chapters. For ES and AL, the percentages of agreement were 72 % for 2nd-level ICF-CY categories and 78 % at the chapter level. Kappa coefficients and confidence intervals were calculated to examine the extent to which the agreements exceed chance. The Kappa value was 0.70 for ES and ALW (SE = 0.015; 95 % confidence interval 0.67–0.72] for 2nd-level ICF-CY categories, and at the level of ICF-CY chapters the Kappa value was 0.72 (SE = 0.015; 95 % CI 0.69–0.75). For ES and AL, the Kappa value for 2nd-level categories was 0.71 (SE = 0.018; 95 % CI 0.68–0.75), and at the chapter level, the Kappa value was 0.72 (SE = 0.020; 95 % CI 0.68– 0.76). These Kappa values indicate substantial agreement. Data analysis Frequency analysis was used to examine the absolute number of studies in which each of the ICF-CY categories were identified, along with the corresponding percentages relative to the total number of studies. ICF-CY categories are presented at the 2nd-level. If a concept is linked to a 3rd- or 4th-level ICF-CY category, the corresponding 2ndlevel category is reported. Because the ICF-CY is organized hierarchically, aspects of the more specific 3rd- and 4th-level categories are included in the less specific 2ndlevel categories. Following the ICF Core Sets development guidelines [16], a 2nd-level ICF-CY category that was identified repeatedly in one and the same study was counted only once. Only ICF-CY categories that were identified in at least 5 % of the publications in the total sample were included in the list of candidate categories. This was done to facilitate the reduction of ICF-CY categories to only those that had the highest frequency in relation to ADHD. Additional frequency analysis was used to explore the possible relation between developmental stage of the participants and ICF-CY categories identified in the study.

Results Study selection The systematic literature search yielded a total of 16,481 citations (including studies, book chapters, dissertations, etc.—see Fig. 2). Out of these, a first sample of 55 citations was selected based on the positive list provided by the Steering Committee (SC). Thereafter, two consecutive, computer-generated random samples of 100 citations were included in the analysis. As a result, a total of 255 citations were included for initial screening. Based on screening, the abstracts and full text of these articles using the eligibility

13

Eur Child Adolesc Psychiatry (2015) 24:859–872 Records aer duplicates removed (n=16,841)

Records screened for inclusion

Records provided by SC

(n=100 x 2)

(n=55)

Records excluded (n=164) excluded publicaon (n=18) excluded design (n=32) excluded populaon (n=49) excluded outcome (n=65)

Full-text arcles assessed for eligibility (n=91)

Records excluded (n=11) excluded publicaon (n=3) excluded design (n=5) excluded populaon (n=1) excluded outcome (n=2)

Full-text arcles included in linking process (n=80)

Unique measures included in linking process (n=226)

Fig. 2  Flow diagram of study selection

criteria described in the Methods section, 175 citations were excluded, leaving a total of 80 studies for inclusion in the data extraction and linking procedures (n  = 49 for the positive list; n  = 16 for the first random sample; and n = 15 for the second random sample). Reasons for exclusion included: citations of an excluded publication type (e.g., books, dissertation abstracts, published in a language other than English—12 %), the main outcome of the studies was not ability or disability in ADHD (e.g., epidemiological studies—38 %), use of an excluded design (i.e., review study or meta-analysis—21 %), or including participants from an excluded population (i.e., those not having a primary diagnosis of ADHD—29 %). After data extraction and linking for the 80 studies data saturation as defined above was reached (see appendix 3 for a full list). Study characteristics Five of the six WHO regions (all except the Africa region) were represented in the sample of included studies. Most of the included studies were conducted in the WHO region of the Americas (n = 42), followed by the European region (n = 28), and the Western Pacific Region (n = 6), including studies from Australia, Japan and Taiwan. Two studies were

Eur Child Adolesc Psychiatry (2015) 24:859–872

conducted in the Eastern Mediterranean region, both in Iran, and two studies were conducted in the South East Asia region, one in India and one in Thailand. About one-third of the studies focused exclusively on children (n = 28), onequarter exclusively on adults (n = 20), and one-fifth exclusively on adolescents (n = 16). The remainder focused on both children and adolescents (n  = 11), both adolescents and adults (n = 4), and one study, investigating registered accidents and injuries in retrospect, included data from individuals across the life span (range: 0–64 years) [43]. A total of n  = 68,221 individuals participated in the 80 eligible studies, with the number of participants per study ranging from n  = 5 to 16,900. Mean age per study ranged from 4.6 years (SD 0.6 years) to 71.6 years (SD 7.7 years), while the range was between 0 and 80 years (43, see above). Sex distribution was evenly balanced (48 % females). However, nearly half of the studies (n  = 35) included more males than females, with a ratio of >3:1. This is likely to reflect the predominance of males in the ADHD population, with ratios between 2 and 5 to 1, that is generally found in epidemiological studies of children and adolescents [44–47]. Two studies did not provide information with regard to the gender of participants. All studies included participants with ADHD as the main diagnosis, 29 studies included a mix of different subtypes, 11 with the combined subtype, six with the hyperactive subtype, one with the inattentive subtype. Thirty-three studies did not specify the ADHD subtype(s) included in the study. Sixty-four studies were observational in nature, including longitudinal and cross-sectional studies; descriptive and case–control studies (ADHD vs typical development or other mental health conditions). Sixteen studies described interventional studies, most of which (n  = 12) described pharmacological interventions (i.e., methylphenidate, buspirone, dextroamphetamine, pemoline, atomoxetine, lisdexamfetamine dimesylate). In two of these studies, medication was combined with cognitive behaviour therapy. Other interventions included unspecified “training programs” directed at improving friendships and homework handling, and mindfulness training for children with ADHD and their parents. Sixteen studies used information obtained from the participants themselves, while 10 studies used information about the functioning of the participants obtained from a proxy (e.g., parents/caregivers, peers). In nine of the studies, information was obtained from professionals working with the participants (e.g., teachers, health care professionals). Twelve studies used information from cognitive skills tests, such as the Wechsler Intelligence Scales for Children and the Stroop Colour-Word Interference Test. Finally, 33 studies used information from a combination of sources. Few differences were identified between characteristics of studies from the positive list and the full sample of studies, except that the positive list contained a larger

865

proportion of observational studies (98 vs 80 %) and a smaller proportion intervention studies (2 vs 20 %). Linking results From the 80 included studies, 226 unique functional outcome measures were extracted and included in the linking process. These included 113 standardized psychometric measures, i.e., questionnaires, rating scales, observation schedules, structured and semi-structured interviews and cognitive tests, such as the ADHD Rating Scale, Child Behaviour Checklist, Vineland Adaptive Behaviour Scales, Wechsler Intelligence Scales for Children, Paediatric Quality of Life Inventory, Adult functioning Interview, and the Beck Depression Inventory (see appendix 4 for a complete list). The remaining 113 measures were non-standardized, e.g., single questions to parents or health professionals, measures designed specifically for a study, information obtained from medical records, and clinical assessments. From these standardized and non-standardized outcome measures included in the linking process, 2578 meaningful concepts were extracted. Following the formalized linking rules [37, 38], 1949 of the meaningful concepts could be linked to ICF-CY categories. Of the 629 concepts that could not be linked, 273 were coded as Personal factors, including general characteristics such as income or living situation; personality characteristics such as being cheerful or feeling guilty; and characteristics related to lifestyle, such as hobbies or alcohol and drug use. An additional 195 concepts were considered not to be covered by the ICF-CY, examples include, self-injurious and destructive behaviours, delinquent behaviours, and having friends who are a bad influence. A total of 123 concepts that were formulated in such general terms that they could not be linked to one specific category and were coded “not definable”, these included terms such as “impairment”, “social skills”, and “problems with behaviour”. Finally, 38 concepts reflected diagnoses or health conditions, such as depression and conduct disorder, and were assigned the code health condition. A total of 1949 meaningful concepts were linked to 128 s level ICF-CY categories. This number was further reduced by selecting from the total sample only those categories that are of higher frequency in ADHD and were identified in at least 5 % of the studies (range 5–53 %). Categories were identified primarily from the Body functions component (n  = 31) and the Activities and Participation component (n  = 32), and to a lesser extent in the Environmental factors component (n  = 5). None of the concepts were linked to categories from the Body structures component. Table 1 presents the second level categories identified in the Body functions component, along with the number and percentage of studies in which they were identified. Most of the categories identified in the Body

13

866

Eur Child Adolesc Psychiatry (2015) 24:859–872

Table 1  Absolute and relative frequencies of ICF-CY categories from the Body functions component 2nd level category

n (%)

b130 energy and drive functions b147 psychomotor functions b140 attention functions b152 emotional functions b144 memory functions b125 dispositions and intra-personal functions b126 temperament and personality functions b156 perceptual functions b167 mental functions of language b280 sensation of pain b160 thought functions b164 higher-level cognitive functions b114 orientation functions b240 sensations associated with hearing and vestibular b535 sensations associated with the digestive system b163 basic cognitive functions b110 consciousness functions b530 weight maintenance functions b134 sleep functions b510 ingestion functions b840 sensations related to the skin b172 calculation functions b220 sensations associated with the eye and adjoining structures

40 (50) 40 (50) 39 (49) 36 (45) 34 (43) 26 (33) 26 (33) 20 (25) 20 (25) 18 (23) 17 (21) 14 (18) 13 (16) 13 (16) 13 (16) 12 (15) 11 (14) 11 (14) 10 (13) 10 (13) 10 (13) 9 (11) 9 (11)

b525 defecation functions b765 involuntary movement functions b117 intellectual functions b460 sensations associated with cardiovascular and respiratory functions

9 (11) 6 (8) 5 (6) 5 (6)

b760 control of voluntary movement functions b265 touch function b330 fluency and rhythm of speech functions

5 (6) 4 (5) 4 (5)

b640 sexual functions

4 (5)

functions component come from chapter b1 mental functions, that covers the functions of the brain. The three most frequently identified categories represent the core ADHD symptom domains, i.e., impulse control (energy and drive functions), hyperactivity (psychomotor functions), and inattention (attention functions). Energy and drive functions represent concepts such as “blurts out answers” and “I am tired all the time”. Psychomotor functions are used to categorise concepts like “fidgets or squirms with hands or feet” and “I feel as if driven by a motor”. Examples of concepts covered by attention functions are “cannot concentrate for longer periods of time” and “easily distracted”. Other categories frequently identified in the chapter of mental functions are emotional functions, representing the

13

experience, regulation and display of emotions, and memory functions, including short- and long-term memory, and the retrieval and processing of memory. The other chapters from which categories were identified are chapter b2 sensory functions and pain (e.g., sensation of pain, dizziness); chapter b3 voice and speech functions (e.g., fluency and rhythm of speech); chapter b4 functions of the cardiovascular, haematological, immunological and respiratory systems (e.g., shortness of breath, irregular heartbeat); chapter b5 functions of the digestive, metabolic and endocrine systems (e.g., nausea, vomiting, weight maintenance); chapter b6 sexual functions (e.g., sexual arousal); chapter b7 neuromusculoskeletal and movement-related functions (e.g., coordination, clumsiness); and chapter b8 functions of the skin and related structures (e.g., itching, tingling). Table  2 shows the absolute and relative frequencies of the second level categories that were identified in the Activities and Participation component. The most frequently identified category was school education from chapter d8 major life areas, which concerns moving into, maintaining, progressing in, and terminating an educational program or school level. Examples of concepts categorised under school education are “repeat a grade” and “fails to finish schoolwork”. Also frequently identified were categories from chapter d7 interpersonal interactions and relationships, i.e., complex interpersonal interactions and informal social relationships. These categories reflect the formation and maintenance of relationships, as well as the appropriate regulation of behaviours within interactions. A third category identified in nearly half of the studies is undertaking a single task, from chapter d2 general tasks and demands, which represents all aspects involved in planning, carrying out and completing a simple or complex task. The other chapters from the Activities and Participation component in which categories were identified are d1 learning and applying knowledge (e.g., reading, writing, focusing attention); d4 mobility (e.g., walking, moving around); d5 selfcare (e.g., toileting, managing diet and fitness, looking after one’s safety); and d9 community, social and civic life (e.g., sports, socializing, community life). Absolute and relative frequencies of the categories identified in the Environmental factors component are summarized in Table 3. Categories were identified in four different chapters, the most frequently identified category coming from chapter e5 services, systems and policies. This category, education and training services, includes school and special education services. The second category identified in this chapter is health services, systems and policies, and represents health services aimed at treating and preventing health problems and promoting a healthy lifestyle. From chapter e1 products and technology comes the category products or substances for personal consumption, which represents food or drugs, including medication. Identified

Eur Child Adolesc Psychiatry (2015) 24:859–872

867

Table 2  Absolute and relative frequencies of ICF-CY categories from the Activities and Participation component

Table 3  Absolute and relative frequencies of ICF-CY categories from the Environmental factors component

2nd level category

n (%)

2nd level category

d820 school education d720 complex interpersonal interactions d210 undertaking a single task d750 informal social relationships d166 reading d172 calculating d160 focusing attention d170 writing d240 handling stress and other psychological demands d760 family relationships d920 recreation and leisure d220 undertaking multiple tasks d570 looking after one’s health d740 formal relationships d250 managing one’s own behaviour d845 acquiring, keeping and terminating a job d530 toileting d910 community life d140 learning to read d145 learning to write d150 learning to calculate d571 looking after one’s safety d450 walking d770 intimate relationships d161 directing attention d177 making decisions d430 lifting and carrying objects d455 moving around d710 basic interpersonal interactions d230 carrying out daily routine d410 changing basic body position

42 (53) 35 (44) 34 (43) 32 (40) 27 (34) 27 (34) 24 (30) 22 (28) 22 (28) 22 (28) 22 (28) 19 (24) 14 (18) 14 (18) 13 (16) 11 (14) 10 (13) 10 (13) 9 (11) 9 (11) 9 (11) 9 (11) 7 (9) 7 (9) 6 (8) 5 (6) 5 (6) 5 (6) 5 (6) 4 (5) 4 (5)

e585 education and training services, systems and policies 20 (25) e110 products or substances for personal consumption 15 (19) e425 individual attitudes of acquaintances, peers, colleagues, 12 (15) neighbours and community members

d830 higher education

4 (5)

in chapter e4 attitudes is the category, individual attitudes of acquaintances, peers, colleagues, neighbours and community members, reflecting attitudes of these (groups of) people that can influence their behaviour towards the individual with a health condition. Finally, the category immediate family, from chapter e3 support and relationships, reflects the physical or emotional support received from immediate family members, such as parents, siblings, partners or children. Additional frequency analysis exploring the possible relationships between the developmental stage of the participants and the concepts measured in the study yielded no surprising findings. Due to the limited number of studies in the different age groups, it was not possible to draw any

N (%)

e310 immediate family

4 (5)

e580 health services, systems and policies

4 (5)

meaningful conclusions. However, a general trend could be detected with educational skills, such as reading, writing and calculating, and school education in general being measured almost exclusively in studies with children and adolescents.

Discussion The purpose of this study was to capture perspectives from published research on what constitutes the relevant aspects of ability and disability in individuals with ADHD of all ages and to translate these into an edited selection of candidate ICF-CY categories for possible inclusion in the ICF Core Sets for ADHD. Applying a formalized procedure developed by the WHO and the ICF Research Branch, we conducted a comprehensive scoping review of the literature on functioning in ADHD, used a structured approach to extract meaningful functioning concepts from standardized and non-standardized measures used in the included studies which were then translated into ICF-CY categories. These methods are unique to the ICF Core Sets development process and were here performed for the first time in ADHD. This review, together with the results from three complementary ongoing preparatory studies, will provide the scientific basis for the ICF Core Sets for ADHD. The current study was not a systematic literature review in the traditional sense, thus labelled comprehensive scoping review instead. Not all studies identified in the literature search were analysed, but a smaller sample of the studies. The total sample size was determined based on the principle of data saturation, as described in the Methods section. Gough and colleagues [48] argued that a literature review does not need to follow one established method for it to be considered systematic, as long as it is undertaken with clear and accountable methods (including strategies to prevent or minimize any potential systematic biases). Still, although the current literature review followed a predetermined and clearly described method, we consider the term comprehensive scoping review to better fit the complete process.

13

868

The three most frequently identified categories in the Body functions component are categories representing the core symptom domains of ADHD; impulse control (b130), inattention (b140), and hyperactivity (b147). It may be confusing to see the core domains of a disorder represented in a classification of disabilities resulting from the disorder, but it appears that these functions are not exclusively regarded by researchers as the core symptoms or domains that define the disorder ADHD but also as important outcomes. In the analysis, only measures identified as outcomes were included, those used for diagnosis were not included. Whilst it could be argued that by definition a diagnosis of ADHD indicates that an individual has impairing problems in the domains of inattention and/or impulsivity and hyperactivity, the diagnosis itself does not describe the extent of these problems, or the different ways and situations in which they manifest or respond to treatment interventions. The classification of these aspects is the specific purpose of the ICF(-CY). Certainly from a clinical perspective, reducing symptoms is an important treatment goal. However, it is also very clear that even when symptom control is good, there are often still continuing functional impairments. A focus on both aspects is therefore very important. Another notable finding is the limited number of Environmental factors that were identified through this review. This suggests that not enough studies have focused on environmental issues with more research focused on environmental aspects needed. In particular, studies that focus on factors represented by chapters e1 products and technology (equipment, products and technologies used by people in various situations and settings, such as teaching materials and methods or general and assistive products for communication) and e3 support and relationships within the social environment would be very helpful. We suspect however that the limited number of Environmental factors that were identified might also be an indication that the environmental component of ICF-CY is somewhat underdeveloped and lacking in detail. Not only does this make it difficult to link environmental factors that may have been measured to appropriate ICF-CY categories (thus resulting in a limited number of identified categories), but also that where information is linked, this is at such a superordinate level that it is difficult to draw any clinically relevant conclusions from it. We propose that further development of the Environmental factors component is needed to optimize the usefulness of the ICF-CY, through the provision of increased levels of detail in this section. As expected, studies identified in this review, all focused on disability in ADHD, and the measures in the studies were used to capture potential impairments, limitations and restrictions. In this study, it was therefore not possible to identify ICF-CY categories that represent specific abilities related to ADHD that may be included in the Core Sets.

13

Eur Child Adolesc Psychiatry (2015) 24:859–872

This observation underscores the predominance of a disability/impairment perspective used in mental health and neurodevelopmental research. However, identification of ability in ADHD remains one of the specific aims of this project and the other three preparatory studies will therefore address this issue in an attempt to identify ICF-CY categories that represent ability in ADHD, in addition to those representing disability. Certain limitations of the study may have led to an under-representation of ICF-CY categories relevant to ADHD. First, there was a restriction of the search results to studies published in English. Indeed, the majority of the studies included in the review were conducted in the US, Canada and European countries. Second, no studies from the African region were included in the sample. Whilst this may reflect a lack of studies conducted in this region, it may also be due to studies from this region more often being published in journals not listed by the major search engines and which therefore would not have been identified through our electronic search strategies. If there are any ICF-CY categories that are specifically relevant in countries that are under-represented in the study, such as low- and middle income countries, these may have been overlooked at this stage in the process. Third, given the large number of studies identified in the initial literature search, it was decided to analyse a smaller sample of studies. Even though measures have been taken to ensure that the “research perspective” was captured comprehensively, including the analysis of the studies provided by the Steering Committee and analysis of additional studies until saturation was reached, it is still possible that a broader range of studies and additional ICF-CY categories would have been identified if a larger selection of studies had been included. To get an indication of how representative the selection of ICF-CY categories identified in this comprehensive scoping literature review is, a comparison was made with the selection of ICF categories included in the Swedish core set for adults with ADHD [31], which was based on a Delphi-exercise and a consensus conference with Swedish professionals from different disciplines with extensive experience in working with adults with ADHD. The comparison showed general agreement, including similar number of categories (n = 66) from the same three components (i.e., Body functions, Activities and Participation, and Environmental factors). However, some differences were also found, such as categories from the Body functions component constitute only mental functions in the selection for the Swedish core set, whereas the selection in the present study also includes more physical functions, such as physical sensations (shortness of breath, irregular heartbeat), pain, and digestive functions (vomiting, weight maintenance). This finding is consistent with the DSM-5 reconceptualization of ADHD as a neurodevelopmental disorder, rather than as a disruptive

Eur Child Adolesc Psychiatry (2015) 24:859–872

behaviour disorder [49]. However, it is possible that these physical functions are not all directly related to ADHD, but that they also represent common side effects of ADHD medication. Even so, they may be relevant to the Core Sets selection, since a large proportion of individuals with ADHD take such medications [50, 51] and may thus be experiencing these side effects. For the Activities and Participation component, there is a considerable overlap of categories, however, unlike the Swedish study, the categories identified in the present study did not include any from the communication and domestic life chapters. On the other hand, some categories from the mobility and community, social and civic life chapters are included here, but are missing from the selection for the Swedish core set. The most striking difference was in the categories identified in Environmental factors. Nineteen categories were identified for inclusion in the Swedish core set, inform across all five chapters in the Environmental factors component, while only five categories were identified in the present study, across four of the chapters. The fact that some categories were included in the selection based on this comprehensive scoping review but not in the selection made by the experts in the Delphi exercise and consensus conference of the Swedish core set, is an indication that it is essential to include multiple perspectives to form a complete picture of functioning in ADHD. This is the reason that the ICF Core Sets development protocols include the four complementary preparatory studies, each covering a different perspective and employing a different research approach. This is designed to ensure that a global perspective on functioning in a certain health condition is captured and to ensure that appropriate implementation of ICF Core Sets is possible. In the expert survey, for example, efforts will be made to ensure that opinion leaders from all six WHO-regions will be included, so that aspects of functioning relevant in low- and middle income countries and across high and low resource environments and cultures will be captured. Furthermore, the focus group study will include children, adolescents and adults, as well as parents, teachers and other people living or working closely with individuals with ADHD in non-clinical settings, so that each of their perspectives on the ICF-CY categories relevant to their specific situations will be included. In addition, the focus groups will be held in various parts of the world so that a global perspective on functioning in ADHD from the client’s point of view is captured. Finally, a group of experts from various backgrounds, disciplines, low-, middle-, and high income countries and cultures across all WHO regions will decide which ICF-CY categories are to be included in the ICF Core Sets for ADHD, ensuring that they will be applicable across both the globe and the life span. Twenty-four percent of the concepts identified in the current review could not be linked to ICF-CY categories. Nearly half of these were found to be Personal factors.

869

These are defined by the ICF(-CY) as features that are intrinsic to the individual and are not part of a health condition. Owing to their large diversity and variety of significance among cultures, they have not yet been systematized within ICF manuals. Current recommendations are that ICF(-CY) users assess and describe them in another manner that is suitable for their practical use. The use of Personal factors needs to be approached with caution, precisely because they are not yet systematized. In a critical examination of the construct of Personal factors in the ICF(-CY), Simeonsson and his colleagues point out that there are considerable risks associated with applying these Personal factors in the absence of formal codes [12]. These include: idiosyncratic use (i.e., each user creates his/ her own definition with inclusion and exclusion criteria), establishment of the component of Personal factors based on exemplars provided by users instead of on a clear definition, and the risk of “blaming the victim” where Personal factors are seen as causal or contributing to an individual’s health condition or disability. On the other hand, Müller and Geyh [11] argue that, despite the potential risks of uncontrolled classification, disregarding personal factors may result in missed opportunities to provide individually targeted interventions and support. Given this debate on the values and the risks of classifying Personal factors, the ongoing development of the ICF Core Sets for ADHD will include a discussion by the Steering Committee and Consensus Conference experts, whether such a more systematic approach to Personal factors would be appropriate, possible and feasible. One-third of the concepts that could not be linked were coded as “not covered”, which means that there were no categories in the ICF-CY to represent these concepts. Among these were concepts describing environmental factors that are likely to have an impact on an individual’s level of functioning, such as the quality of the relationship between the parents, and being bullied or rejected by peers. One could argue that these concepts could be linked to categories representing support from parents (e310) and support from peers (e325). However, low quality of the relationship between parents does not necessarily mean that there is a lack of support to the child. Similarly, bullying or rejection involves more than simply a lack of support from peers. Therefore, it was decided not to link these concepts to categories representing possibly underlying or resulting factors, but instead to code them as “not covered”. Other concepts that were coded “not covered” included those describing behaviours that are often associated with ADHD, such as sexual, delinquent and (self-)destructive behaviours. Even though these behaviours may give an indication of the level of functioning of an individual, they do not necessarily represent functional disabilities in themselves. For example, having multiple sexual partners

13

870

could be an indication of an impulsive approach to sexual relationships or inability to form intimate relationships, but it could also result from a personal preference for being free and uncommitted. This could explain why there were no fitting categories available in the ICF-CY to link these concepts. In conclusion, a wide variety of ICF-CY categories was identified in the current study, covering three of the four ICFCY components and the majority of chapters within these components. In addition, this comprehensive scoping literature review resulted in a slightly different selection of categories than a previous study in which experts selected categories based on their extensive experience in working with individuals with ADHD [31]. These findings underline the necessity to regard ability and disability in ADHD from various perspectives to gain a complete and comprehensive picture. Not only is this an encouragement for future research to keep a broad focus on functioning in all areas of life, it also provides evidence for the need for tools that can facilitate and standardize such a broad focus. By providing scientifically derived clear guidelines about “what to measure” to conduct a comprehensive assessment of ability and disability in individuals with ADHD, the ICF Core Sets for ADHD will provide a valuable opportunity to fulfil that need. Acknowledgments  The development of the ICF 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. This Steering Committee consists of the co-authors of this paper and Heidi Bernhardt, Susan Shur-Fen Gau, Judith Hollenweger, Michael Rösler, Melissa Selb, Susan Swedo and Bedirhan Üstün. The development of ICF Core Sets for ADHD is supported by the Swedish Research Council (grant no. 523-2009-7054), and the Swedish Research Council in partnership with FAS (now renamed FORTE), FORMAS and VINNOVA (trans-disciplinary research program on child and youth mental health, grant no. 259-2012-24). Conflict of interest  Prof. Petrus J. de Vries is a member of the study steering groups of three clinical trials funded by Novartis, and on the scientific advisory board of a natural history study of tuberous sclerosis complex, also funded by Novartis. He is co-PI on two phase II clinical trials part-funded by Novartis and has received honoraria for advisory board membership from Novartis. Martin Holtmann served in an advisory or consultancy role for Lilly and Shire, and received conference attendance support or was paid for public speaking by Bristol-Myers Squibb, Lilly, Medice, Neuroconn, Novartis and Shire. Dr. Luis Augusto Rohde has been a member of the speakers’ bureau/ advisory board and/or acted as a consultant for Eli-Lilly, JanssenCilag, Novartis and Shire in the last 3 years. He receives authorship royalties from Oxford Press and ArtMed. He has also received travel awards from Shire for his participation of the 2014 APA meeting. The ADHD and Juvenile Bipolar Disorder Outpatient Programs chaired by him received unrestricted educational and research support from the following pharmaceutical companies in the last 3 years: Eli-Lilly,

13

Eur Child Adolesc Psychiatry (2015) 24:859–872 Janssen-Cilag, Novartis, and Shire. Rosemary Tannock is an advisory board member for the Canadian ADHD Resource Alliance (CADDRA) and has acted as a consultant for the Ministry of Education of Newfoundland and Labrador, Shire and Purdue, in the last 3 years. She receives authorship royalties from Springer and Cambridge University Press. In 2014, she received a travel award from Biomed Central publishers for her participation in an Editor’s meeting and from Shire for her scientific presentation on DSM-5 at their industry sponsored conference. Pearson-Cogmed has provided software licences at no cost for her externally-funded research on working memory training in ADHD. Sven Bölte has acted as a consultant for Roche, Eli Lilly and ProPhase in the last 3 years, and receives royalties from Hogrefe/Huber publishers. On behalf of the remaining authors, the corresponding author states that there is no conflict of interest.

References 1. Polanczyk G, de Lima MS, Horta BL, Biederman J, Rohde LA (2007) The worldwide prevalence of ADHD: a systematic review and metaregression analysis. Am J Psychiat 164:942–948 2. Polanczyk GV, Willcutt EG, Salum GA, Kieling C, Rohde LA (2014) ADHD prevalence estimates across three decades: an updated systematic review and meta-regression analysis. Int J Epidemiol 43:434–442 3. Simon V, Czobor P, Bálint S, Mészáros Á, Bitter I (2009) Prevalence and correlates of adult attention-deficit hyperactivity disorder: meta-analysis. Br J Psychiatry 194:204–211 4. Nigg JT (2013) Attention-deficit/hyperactivity disorder and adverse health outcomes. Clin Psychol Rev 33:215–228 5. Spencer TJ, Biederman J, Mick E (2007) Attention-deficit/hyperactivity disorder: diagnosis, lifespan, comorbidities, and neurobiology. J Pediatr Psychol 32:631–642 6. Danckaerts M, Sonuga-Barke EJS, Banaschewski T, Buitelaar J, Döpfner M, Hollis C, Santosh P, Rothenberger A, Sergeant J, Steinhausen HC, Taylor E, Zuddas A, Coghill D (2010) The quality of life of children with attention deficit/hyperactivity disorder: a systematic review. Eur Child Adolesc Psychiatry 19:83–105 7. Agarwal R, Goldenberg M, Perry R, Ishak WW (2012) The quality of life of adults with attention deficit hyperactivity disorder: a systematic review. Innov Clin Neurosci 9:10–21 8. Shaw M, Hodgkins P, Caci H, Young S, Kahle J, Woods AG, Arnold LE (2012) A systematic review and analysis of long-term outcomes in attention deficit hyperactivity disorder: effects of treatment and non-treatment. BMC Med 10:99 9. Üstün B (2007) Using the International Classification of Functioning, Disease and Health in attention-deficit/hyperactivity disorder: separating the disease from its epiphenomena. Ambul Pediatr 7:132–139 10. World Health Organization (2001) International Classification of Functioning, Disability and Health: ICF. World Health Organization, Geneva 11. Müller R, Geyh S (2014) Lessons learned from different approaches towards classifying personal factors. Disabil Rehabil (Epub ahead of print) 12. Simeonsson RJ, Lollar D, Björck-Åkesson E, Granlund M, Brown SC, Zhuoying Q, Gray D, Pan Y (2014) ICF and ICF-CY lessons learned: Pandora’s box of personal factors. Disabil Rehabil 36:2187–2194 (Epub ahead of print) 13. World Health Organization (2007) International Classification Of Functioning, Disability And Health: Children And Youth Version: ICF-CY. World Health Organization, Geneva 14. Stucki G, Grimby G (2004) Applying the ICF in medicine. J Rehabil Med 36(Suppl 44):5–6

Eur Child Adolesc Psychiatry (2015) 24:859–872 15. Üstün B, Chatterji S, Kostanjsek N (2004) Comments from WHO for the Journal of Rehabilitation Medicine special supplement on ICF Core Sets. J Rehabil Med 36(Suppl. 44):7–8 16. Selb M, Escorpizo R, Kostanjsek N, Stucki G, Üstün B, Cieza A (2014) A guide on how to develop an International Classification of Functioning, Disability and Health Core Set. Eur J Phys Rehab Med [Epub ahead of print] 17. Kirchberger I, Cieza A, Biering-Sørensen F, Baumberger M, Charlifue S, Post MW, Campbell R, Kovindha A, Ring H, Sinnott A, Kostanjsek N, Stucki G (2010) ICF Core Sets for individuals with spinal cord injury in the early post-acute context. Spinal Cord 48:297–304 18. Cieza A, Kirchberger I, Biering-Sørensen F, Baumberger M, Charlifue S, Post MW, Campbell R, Kovindha A, Ring H, Sinnott A, Kostanjsek N, Stucki G (2010) ICF Core Sets for individuals with spinal cord injury in the long-term context. Spinal Cord 48:305–312 19. Ruof J, Cieza A, Wolff B, Angst F, Ergeletzis D, Omar Z, Kostanjsek N, Stucki G (2004) ICF Core Sets for diabetes mellitus. J Rehabil Med Suppl. 44:100–106 20. Brach M, Cieza A, Stucki G, Füssl M, Cole A, Ellerin B, FialkaMoser V, Kostanjsek N, Melvin J (2004) ICF Core Sets for breast cancer. J Rehabil Med (Suppl 44):121–127 21. Castro S, Ferreira T, Dababnah S, Pinto AI (2013) Linking autism measures with the ICF-CY: functionality beyond the borders of diagnosis and interrater agreement issues. Dev Neurorehabil 16:321–331 22. Chien CW, Rodger S, Copley J, Skorka K (2014) Comparative content review of children’s participation measures using the International Classification of Functioning, Disability and Health-Children and Youth. Arch Phys Med Rehab 95:141–152 23. Gleason K, Coster W (2013) An ICF-CY-based content analysis of the Vineland Adaptive Behavior Scales-II. J Intellect Dev Dis 37:285–293 24. Gan SM, Tung LC, Yeh CY, Wang CH (2013) ICF-CY based assessment tool for children with autism. Disabil Rehabil 35:678–685 25. Ibragimova N, Granlund M, Björck-Åkesson E (2009) Field trial of ICF version for children and youth (ICF-CY) in Sweden: logical coherence, developmental issues and clinical use. Dev Neurorehabil 12:3–11 26. Poon KK (2011) The activities and participation of adolescents with autism spectrum disorders in Singapore: findings from an ICF-based instrument. J Intell Disabil Res 55:790–800 27. Brütt AL, Schulz H, Andreas S (2013) Development of an ICFbased core set of activities and participation for patients with mental disorders: an approach based upon data. Clin Rehabil 27:758–767 28. Castro S, Pinto AI (2013) Identification of core functioning features for assessment and intervention in autism spectrum disorders. Disabil Rehabil 35:125–133 29. Cieza A, Chatterji S, Andersen C, Cantista P, Herceg M, Melvin J, Stucki G, de Bie R (2004) ICF Core Sets for depression. J Rehabil Med (Suppl 44):128–134 30. Ayuso-Mateos JL, Ávila CC, Anaya C, Cieza A, Vieta E, the Bipolar Disorders Core Sets Expert Group (2013) Development of the International Classification of Functioning, Disability and Health core sets for bipolar disorders: results of an international consensus process. Disabil Rehabil 35:2138–2146 31. Söderström S, Pettersson R, Edlund-Söderström K, Ganse G, Holmkvist E, Westin O, Haglund L (2014) Development of a Swedish comprehensive International Classification of Functioning, Disability and Health (ICF) core set for adult patients with attention-deficit hyperactivity disorder (ADHD). Nord J Psychiat 68:161–168

871 32. Bölte S, De Schipper E, Holtmann M, Karande S, De Vries PJ, Selb M, Tannock R (2013) Development of ICF Core Sets to standardize assessment of functioning and impairment in ADHD: the path ahead. Eur Child Adolesc Psychiatry (Epub ahead of print) 33. Schiariti V, Klassen AF, Cieza A, Sauve K, O’Donnell M, Armstrong R, Mâsse LC (2014) Comparing contents of outcome measures in cerebral palsy using the international classification of functioning (ICF-CY): a systematic review. Eur J Paediatr Neuro 18:1–12 34. Post MWM, Kirchberger I, Scheuringer M, Wollaars MM, Geyh S (2010) Outcome parameters in spinal cord injury research: a systematic review using the International Classification of Functioning, Disability and Health (ICF) as a reference. Spinal Cord 48:522–528 35. Ávila CC, Cabello M, Cieza A, Vieta E, Ayuso-Mateos JL (2010) Functioning and disability in bipolar disorders: a systematic review of literature using the ICF as a reference. Bipolar Disord 12:473–482 36. Brockow TT, Wohlfahrt K, Hillert A, Geyh S, Weigl M, Franke T, Resch KL, Cieza A (2004) Identifying the concepts contained in outcome measures of clinical trials on depressive disorders using the International Classification of Functioning, Disability and Health as a reference. J Rehabil Med Suppl. 44:49–55 37. Cieza A, Brockow T, Ewert T, Amman E, Kollerits B, Chatterji S, Üstün B, Stucki G (2002) Linking health-status measurements to the International Classification of Functioning, Disability and Health. J Rehabil Med 34:205–210 38. Cieza A, Geyh S, Chatterji S, Kostanjsek N, Üstün B, Stucki G (2005) ICF linking rules: an update based on lessons learned. J Rehabil Med 37:212–218 39. Guest G, Bunce A, Johnson L (2006) How many interviews are enough? An experiment with data saturation and variability. Field Methods 18:59–82 40. Morse JM (1995) The significance of saturation. Qual Health Res 5:147–149 41. Ávila CC, Alarcos C, Anaya C, Ayuso-Mateos JL (2012) The patients’ perspective on relevant areas and problems in the bipolar spectrum disorder: individual interviews using the International Classification of Functioning, Disability and Health as a reference tool. Am J Phys Med Rehab 91(suppl):s181–s188 42. Glässel A, Finger ME, Cieza A, Treitler C, Coenen M, Escorpizo R (2011) Vocational rehabilitation from the client’s perspective using the International Classification of Functioning, Disability and Health (ICF) as a reference. J Occup Rehabil 21:167–178 43. Swensen A, Birnbaum HG, Hamadi RB, Greenberg P, Cremieux PY, Secnik K (2004) Incidence and costs of accidents among attention-deficit/hyperactivity disorder patients. J Adolescent Health 35:346 e1–346 e9 44. Froehlich TE, Lanphear BP, Epstein JN, Barbaresi WJ, Katusic SK, Kahn RS (2007) Prevalence, recognition, and treatment of attention-deficit/hyperactivity disorder in a national sample of US children. Arch Pediat Adol Med 161:857–864 45. Nøvik TS, Hervas A, Ralston SJ, Dalsgaard S, Rodrigues Pereira R, Lorenzo MJ (2006) Influence of gender on attention-deficit/ hyperactivity disorder in Europe—ADORE. Eur Child Adolesc Psychiatry 15(Suppl 1):I/15–I/24 46. Ramtekkar UP, Reiersen AM, Todorov AA, Todd RD (2010) Sex and age differences in attention-deficit/hyperactivity disorder symptoms and diagnoses: implications for DSM-V and ICD-11. J Am Acad Child Psy 49:217–228 47. Booth A (2001) Cochrane or cock-eyed? How should we conduct systematic reviews of qualitative research? Paper presented at the qualitative evidence-based practice conference: taking a critical stance. Conventry, UK

13

872 48. Gough D, Thomas J, Oliver S (2012) Clarifying differences between review designs and methods. Syst Rev 1:28 49. American Psychiatric Association (2013) Diagnostic and statistical manual of mental disorders: DSM-5. American Psychiatric Association, Washington, DC 50. Visser SN, Danielson ML, Bitsko RH, Holbrook JR, Kogan MD, Ghandour RM, Perou R, Blumberg SJ (2013) Trends in the parent-report of health care provider-diagnosed and medicated

13

Eur Child Adolesc Psychiatry (2015) 24:859–872 attention-deficit/hyperactivity disorder: United States, 20032011. J Am Acad Child Adolesc Psychiatry (Epub ahead of print) 51. Christensen L, Sasané R, Hodgkins P, Harley C, Tetali S (2010) Pharmacological treatment patterns among patients with attention-deficit/hyperactivity disorder: retrospective claims-based analysis of a managed care population. Curr Med Res Opin 26:977–989