Harmonizing WHO’s International Classification of Diseases (ICD) and International Classification of Functioning, Disability and Health (ICF): importance and methods to link disease and functioning
© Escorpizo et al.; licensee BioMed Central Ltd. 2013
Received: 11 March 2013
Accepted: 5 August 2013
Published: 12 August 2013
To understand the full burden of a health condition, we need the information on the disease and the information on how that disease impacts the functioning of an individual. The ongoing revision of the International Classification of Diseases (ICD) provides an opportunity to integrate functioning information through the International Classification of Functioning, Disability and Health (ICF).
Part of the ICD revision process includes adding information from the ICF by way of “functioning properties” to capture the impact of the disease on functioning. The ICD content model was developed to provide the structure of information required for each ICD-11 disease entity and one component of this content model is functioning properties. The activities and participation domains from ICF are to be included as the value set for functioning properties in the ICD revision process.
The joint use of ICD and ICF could create an integrated health information system that would benefit the implementation of a standard language-based electronic health record to better capture and understand disease and functioning in healthcare.
KeywordsInternational classification of diseases ICF Classification Functioning ICD revision Disability
Describing and understanding the relationship between disease and functioning requires the use of two of the World Health Organization’s classifications systems: the International Classification of Diseases (ICD)  and the International Classification of Functioning, Disability and Health (ICF) . The ICD classifies disease entities and other health conditions to gather diagnostic information, while the ICF classifies domains of functioning and disability in terms of body functions and structures or activities and participation at the body, person and societal levels. The ICD and the ICF classification systems are intended by WHO to complement each other so as to capture and provide the full picture of health or health-related state of an individual. Currently, however, there is no standard platform in which the disease and its impact on functioning are concurrently used within an integrated health information system. Efforts to capture the impact of a disease in a structured and systematic way have so far been hampered by the failure to link the ICD and the ICF at a conceptual and operational level.
The ICD is undergoing its 11th revision (ICD-11)  wherein part of the process is to add information from the ICF to the classification of diseases by adding “functioning properties” (i.e. ICF domains or codes) to capture the impact of the disease on functioning. In this integrated system, we want to be able to use universal domains (functioning properties) that depict the functioning of an individual by way of the ICF and also use information related to disease entities (ICD codes).
The process of revising the ICD is coordinated through Topic Advisory Groups (TAGs), each of which is responsible for different content areas. Responsible for the appropriate integration of the functioning properties is the Functioning Topic Advisory Group (fTAG), which consults with each of the TAGs regarding how to deal with functioning properties for their assigned ICD entities.
Functioning properties of the ICD-11 content model
The Content Model of the ICD 11 
Any category in ICD is represented by: TITLE of ENTITY: Name of disease, disorder, or syndrome
1. ICD Concept Title
8. Temporal Properties
1.1 Fully Specified Name
8.1 Age of Occurrence & Occurrence Frequency
8.2 Development Course / Stage
2. Classification Properties
9. Severity of Subtypes Properties
2.3 Use and Linearization(s)
3. Textual Definition(s)
10. Functioning Properties
10.1 Impact on Activities and Participation
10.2 Contextual Factors
10.3 Body Functions
11. Specific Condition Properties
4.1 Base Index Terms
11.1 Biological Sex
4.2 Inclusion Terms
11.2 Life-Cycle Properties
5. Body Structure Description
12. Treatment Properties
5.1 Body System(s)
5.2 Body Part(s) [Anatomical Site(s)]
6. Manifestation Properties
13. Diagnostic Criteria
6.1 Signs and Symptoms
6.2 Investigation Findings
7. Causal Properties
14. External Causes
7.1 Etiology Type
7.2 Causal Properties- Agents
7.3 Causal Properties- Causal Mechanisms
7.4 Genomic Linkages
7.5 Risk Factors
List of ICF-based functioning properties value set for an ICD code
Communicating with others
Starting a conversation
Sustaining a conversation
Maintaining a body position
Lifting and carrying objects
Fine hand use
Hand and arm use
Walking short distances
Walking long distances
Moving around within home
Moving around outside the home and other buildings
Caring for body parts
Managing one’s health (needs, assistance or oversight)
Engaging with other people
Maintaining family relationships
Dealing with strangers
Engaging in sexual relationships
Looking after/helping others
Learning a job (vocational training, apprenticeship)
Going to university
Work and economic life
Engaging in paid work
Performing job related tasks
Undertaking a single task
Undertaking multiple tasks
Carrying out daily routine
Handling stress and psychological demands
Taking part in social life
Human rights (e.g. self-determination, equal opportunities)
Political life and citizenship (e.g. voting)
Children and Youth
Learning to read
Learning to write
Learning to calculate
Communicating with others
Playing with others
The task of populating the functioning properties in iCAT
Before ICD-11 is completed, functioning properties will need to be populated for each ICD code. This task of population is being done and coordinated using the web-based International Collaborative Authoring Tool (iCAT) by content experts worldwide in three steps:  selection of functioning properties provided in iCAT (Table 2),  if an additional ICF domain or category needs to be added based on a published disease-specific ICF Core Set, then it is entered manually into the iCAT, and  use evidence from the literature (i.e. mini-review) by identifying the commonly used measures relevant to the disease of interest, and in those measures identify meaningful concepts of functioning with a focus on activities and participation in life situations, and then subsequently link the identified concepts to a specific domain in the ICF .
Obtaining information about disease entities and their impact on functioning is not entirely new in the field of medicine and health. While the consideration of the disease and its impact on functioning has been in place, or at least acknowledged, for a long time,  there remain prevailing issues, such as the lack of wide dissemination and implementation extending beyond simple awareness [7, 8]. The operationalization of integrated disease-and-functioning models currently varies, is fragmented across healthcare settings, and is perhaps more commonly observed in healthcare systems with medium to advanced infrastructures and access to resources. We can do a better job at facilitating an integrated disease-and-functioning model across systems from low to high resource countries. Moreover, the ongoing ICD revision would make the assessment and documentation of a comprehensive set of information about a disease entity as broad and as inclusive as possible; at the same time utilizing the standard and common language of the ICF on functioning. This information will consist of biomedical and biopsychosocial aspects of the disease that will provide clinicians and users alike an integrated and unified ICD-ICF platform and which will be helpful in interdisciplinary communication towards a concerted planning of care ultimately benefiting the patients.
The ICD-11 is due to be launched in 2015, and steps toward that goal are being pursued. Certainly there are challenges on our way, but there are also opportunities that are presented for users in the clinical and research communities to actively contribute in this huge endeavor by WHO and its collaborators worldwide. The unified ICD-ICF in the ICD-11 will allow for consistent terminologies to be used and to be harmonized across ICD and ICF and will provide holistic information about a disease entity and its impact on the functioning of an individual. Efforts are also currently being taken to facilitate the identification of the overlaps for ICD-11 disease entities and their titles with their conceptual equivalent in the ICF towards harmonization of ICD and ICF.
The joint use of the ICD and ICF towards an integrated health information model would, in our opinion, benefit medicine and health systems and would support the push for the implementation of a standard language-based electronic health record system towards better health services planning and reimbursement.
RE is Assistant Professor, Department of Physical Therapy, School of Allied Health Professions Louisiana State University Health Sciences Center, New Orleans LA USA; adjunct research scientist at the ICF Research Branch in cooperation with the WHO Collaborating Centre for the Family of International Classifications in Germany (DIMDI), Nottwil, (Switzerland); and the Swiss Paraplegic Research (SPF), Nottwil, Switzerland.
NK is technical officer at World Health Organization, Classifications, Terminologies and Standards (CTS), Department of Health Statistics and Informatics (HSI), Geneva, Switzerland.
CK is with the US Department of Health and Human Services, Office of Health Policy Washington D.C., USA.
MMRN is technical officer at World Health Organization, Classifications, Terminologies and Standards (CTS), Department of Health Statistics and Informatics (HSI), Geneva, Switzerland.
GS is director of the ICF Research Branch in cooperation with the WHO Collaborating Centre for the Family of International Classifications in Germany (DIMDI), Nottwil, (Switzerland) and the Swiss Paraplegic Research (SPF), Nottwil, Switzerland; is Professor and Chair at the Department of Health Sciences and Health Policy, University of Lucerne, Lucerne, Switzerland.
TBU is head of WHO’s Family of International Classifications, Geneva, Switzerland.
R Escorpizo is an employee of the Louisiana State University Health Sciences Center (LSUHSC). This article was developed in his professional capacity and does not necessarily represent the views of LSUHSC.
C Kennedy is an employee of the Office of the Assistant Secretary for Planning and Evaluation (ASPE), Department of Health and Human Services (HHS). This article was developed in her professional capacity and does not necessarily represent the views of ASPE or HHS.
Functioning Topic Advisory Group
International Collaborative Authoring Tool
International Classification of Diseases
International Classification of Functioning, Disability and Health
Topic Advisory Group
World Health Organization.
Special thanks to Melissa Selb, ICF Research Branch coordinator in Nottwil, Switzerland and members of the functioning Topic Advisory Group.
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