The World Health Organization (WHO) International Classification of Functioning, Disability and Health (ICF) was designed to provide a universally accepted description of health-related functioning in different conditions and condition groups, and the Child and Youth version (ICF-CY) was later developed to describe functional aspects in developing individuals using categories from the ICF. Describing an individual using all of the ICF-CY categories is time consuming, therefore the ICF Core Sets were developed to provide shortlists of categories that are relevant to specific health conditions. The development of ICF Core Sets involves four preparatory studies: a clinical study, a scoping literature review, an expert survey and a qualitative study, and involves input from professionals and stakeholders across all WHO world regions. The present study (the clinical study) will therefore contribute to the development of standardised ICF Core Sets for ADHD. This international, cross-sectional, multicentre study, involving 9 clinics from 8 countries across 4 WHO world regions, aimed to evaluate functional and contextual features in children, adolescents and adults with ADHD, as assessed by the ICF-CY in a clinical practice setting, and also assessed environmental barriers and facilitators, and strengths associated with ADHD.
The WHO ICF checklist comprises four components: body functions; body structures; activities and participation; and environmental factors. Across the four components, there are 123 second-level categories that describe basic levels of functioning: there are 31 categories in the body functions component; 12 in body structures; 48 in activities and participation; and 32 in environmental factors. In this study, based on the results of the other three preparatory studies, an extended version of the checklist was used to assess functional abilities* and disabilities† in individuals with ADHD, increasing the specificity of the checklist by including additional ICF-CY categories: 12 in body functions; 14 in activities and participation; and 4 in environmental factors.
A total of 112 participants with ADHD with or without psychiatric comorbidities completed the study between March and August 2016. Overall, 51 children (aged 6–12 years; mean age 9.0±1.8 years; 86% male), 17 adolescents (aged 13–17 years; mean age 14.3±1.6 years; 76% male) and 44 adults (aged ≥18 years; mean age 37.3±11.7 years; 34% male) were included in the study. The majority of participants had combined ADHD (n=76; 68%), and the most frequently reported psychiatric comorbidities were neurodevelopmental disorders (n=25; 22%) and mood disorders (n=17; 15%), followed by externalising behaviour problems (n=10; 9%) and learning disorders (n=7; 6%).
A total of 113 ICF-CY categories were identified in ≥10%‡ of participants and were distributed across 3 out of the 4 ICF-CY components: 50 from activities and participation; 33 from environmental factors; and 30 from body functions. No body structure categories were identified in ≥10% of participants.
The second-level categories most commonly identified as difficulties/challenges by people with ADHD within each of the 3 components were as follows:
- Activities and participation component: “focusing attention” (n=102; 91%), “directing attention” (n=102; 91%) and “undertaking multiple tasks” (n=91; 81%)
- Environmental factors component: “immediate family” (n=95; 84%), “individual attitudes of immediate family members” (n=88; 78%) and “health professionals” (n=81; 72%)
- Body functions component: “attention functions” (n=108; 96%), “higher-level cognitive function” (n=79; 70%) and “emotional functions” (n=75; 66%).
The three most commonly identified ADHD-related strengths were “temperament and personality functions” (n=27; 24%), “recreation and leisure” (n=21; 18%) and “dispositions and intra-personal functions” (n=20; 17%). Additionally, personal factors impacting either positively or negatively on the daily lives of people with ADHD were identified as empowerment, affability, intelligence-related factors, methodical skills and financial situation.
This study reported several methodological limitations. Firstly, although participants from 4 WHO world regions were included in this study, Africa and the Americas were not represented, which may limit the global generalisability of this study. The authors state that they plan to address cultural differences in ADHD functioning and environment by pooling data from the different preparatory studies in a separate article. Secondly, despite the fact that this study included children, adolescents and adults with ADHD, gender and age differences were not investigated, which may have led to potentially biased results. Finally, unlike child and adolescent participants, the ICF-CY checklist for adults was completed without having full access to participants’ medical records and this may have limited the clinical assessment of functioning in adult participants with ADHD.
To conclude, this study assessed the abilities and disabilities of children, adolescents and adults with ADHD, in addition to environmental barriers, facilitators and personal factors. The most commonly identified difficulties associated with ADHD related to tasks and actions requiring attention, as well as the undertaking of multiple tasks and daily routines. Learning and applying knowledge and dealing with attitudes from immediate family members and healthcare professionals were also identified by participants as challenges. However, various strengths associated with ADHD were also reported and included affability, empowerment and social skills. These data will aid the development of the first ICF Core Sets for ADHD, which will become a standardised metric tool to assess functioning in individuals with ADHD.
*A strength/functional ability was defined as a specific ability that an individual with ADHD may be better at compared with the general population. To minimise over- or underestimation, the participant was asked for examples and clarification
†An adapted version of the Numerical Rating Scale (NRS) was used to rate each ICF-CY category using an 11-point scale, with 0 representing “no”, 1–3 “mild”, 4–6 “moderate” and 7–10 “severe symptom impairment”. The NRS was also used to rate environmental factors, with 0 representing “no barrier or facilitator”, +10 “complete facilitator” and -10 “complete barrier”. “Not applicable” and “not specified” were also used if a specific ICF-CY category was not applicable to the individual or if there was not enough information to rate that specific category, respectively
‡Any ICF-CY category rated ≥2 in ≥10% of cases was included as a candidate category for the development of the ICF Core Set. The decision to use a 10% cut-off was based on results from previous ICF clinical studies, and this cut-off was also used to rate ADHD-associated strengths
Mahdi S, Ronzano N, Knüppel A, et al. An international clinical study of ability and disability in ADHD using the WHO-ICF framework. Eur Child Adolesc Psychiatry 2018; 27: 1305-1319.