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 Table of Contents  
Year : 2018  |  Volume : 34  |  Issue : 5  |  Page : 86-90

Classificatory systems and disability

Department of Psychiatry, GMCH, Chandigarh, India

Date of Web Publication20-Nov-2018

Correspondence Address:
Dr. B S Chavan
Department of Psychiatry, GMCH, Chandigarh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijsp.ijsp_33_18

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It is generally accepted that disability represents a construct relevant to mental health, with important implications for the categorization of the clinical course and outcome of mental disorders. Thus, it appears that functional impairment should be built into the configuration of an appropriate diagnostic and classification system of mental disorders. The new model of disability adopted in the International Classification of Functioning, Disability and Health (ICF) proved to be valid and cross-culturally applicable. The ICF could be used as a guide for the incorporation of functional impairment in the new classificatory systems. The joint use of the International Classification of Disease and ICF would benefit medicine and health systems toward better health services planning and reimbursement.

Keywords: Classificatory systems, disability, ICF, functioning

How to cite this article:
Chavan B S, Mehta S. Classificatory systems and disability. Indian J Soc Psychiatry 2018;34, Suppl S1:86-90

How to cite this URL:
Chavan B S, Mehta S. Classificatory systems and disability. Indian J Soc Psychiatry [serial online] 2018 [cited 2022 Jan 26];34, Suppl S1:86-90. Available from: https://www.indjsp.org/text.asp?2018/34/5/86/245828

  Introduction Top

Psychiatric disorders are recognized as aberration in behavior, ideation, and emotion against a normative backdrop,[1] although it is difficult to ascertain normal human behavior and psychiatric symptoms are ubiquitous and quite unstable over time.[2]

The focus of the field of psychiatry is gradually shifting from treatment of symptoms to rehabilitation. The force behind this change has been the International Classification of Functioning, Disability and Health (ICF) published by the World Health Organization (WHO) in 2001.[3]

  Historical Aspect of Classification of Disability Top

Historically, the classification of people with disability was intended to distinguish persons who would require social benefits, either from the government or the religious organizations. The model that subserved this conceptualization has been termed the “charity Model.” This model recognizes persons with disabilities as sufferers of their impairment; and labels them as debilitated, dependent, or as victims of neglect by the society. The paramount response to such persons under the charity model has been to provide them support and shelter.[4] The charity model resulted in some political gains, but this model made persons with disability more dependent and restricted the scientific study of disability.[4]

The “medical model” of disability perceived disability as a sequela of a defect or disease in the body of an individual. It is believed that this defect or disease hampers the functioning and quality of life of the person and that it can be improved with substantive medical interventions.[5] In the medical model, the locus is the person and outside support is to help him adapt to the society. The model evades environmental factors; as a result, there is excessive allocation of resources to technical inputs (e.g., medical, surgical and occupational facilities, prosthesis, medical and genetic screening, etc.) rather than environmental adaptations which might prove to be more beneficial.

The “social model” of disability shifts the focus of disability conceptualization to the external environment.[6],[7] The foundational core of the social model is based on equality and dignity. According to the social model persons with disability can be encouraged to live a life with dignity through change in attitude of the society, sharing of information, removal of physical barriers, and embracing flexible work schedule and social support. The model advocates that persons with disability should be seen as unique and efforts should be made to accept their uniqueness, rather than finding out their imperfections/deficiencies and attempts should be made to harmonize the diversity.

The “rights-based model” is fraternal to the social model of disability. It strives for the fulfillment of human rights of people with disability at par with other members of the society; as the rigid norms of the society deny or limit rights to persons with disability, for example, right to equal opportunities and participation in society. The rights-based model envisions that support in these areas is not a question of humanity or charity, rather a basic human right that any person can claim. The fundamental elements of the rights-based approach are empowerment and accountability; empowerment to participate as active stakeholders and accountability of public institutions and structures to the invocation of these rights.[8] The United Nations Convention on Rights of Persons with Disability (UNCRPD) enshrines this perspective on disability. Under obligation to bring all the existing legislations in conformity with UNCRPD, India, has already amended its Mental Health Act (1987) and Persons with Disability Act (1995), leading to the Mental Health Care Act 2017 and Rights of Persons with Disability Act 2016.

  Classification of Disability Top

There have many attempts to measure and quantify disability secondary to social insurance and health surveys.

Activities of daily living

Katz and Lawton were the first to develop sets of questions based on behavioral manifestation of disability and these were called activities of daily living (ADL).[3],[9] Despite their wide use, ADL-based surveys were criticized as they depended on self-reports of the participants, which were difficult to standardize. Such an approach to measure disability was also criticized on the ground that ADLs do not provide information on social contributors to disability.

International Classification of Impairment, Disabilities and Handicapped

was developed in the 1980s to overcome limitations of ADL-based quantification of disability.[10] It set out to classify a broad range of disability based on both physical and social dimensions. The International Classification of Impairment, Disabilities and Handicapped (ICIDH) provides a conceptual framework for disability in three domains – impairment, disability, and handicap. Impairment was defined as a loss or abnormality of physical bodily structure or function due to psychic, physiological, or anatomical cause; disability as any limitation or functional loss resulting from impairment that prevents the performance of an activity which is considered normal for a human being; and handicap as the disadvantaged condition deriving from impairment or disability limiting a person performing a role considered normal in respect of age, sex, and social and cultural factors.[10] In ICIDH, the impairment is conceptualized to occur at the level of organ or system function, disability at the level of functional performance or activity and handicap at the level of interaction with and adaptation to the person's surroundings. To measure this, the Disability Assessment Schedule WHO-DAS was published by the WHO in 1988 as an instrument mainly for psychiatric inpatients.[11]

International Classification of Functioning, Disability and Health

The ICIDH was revised to International Classification of Functioning, Disability and Health (abbreviated as “ICF”) in 2001. ICF perceives functioning and disability as a complex interaction between the health of the individual, the contextual factors of the environment, and the personal factors. It is structured around the following broad dimensions: body functions and structure, activities (related to tasks and actions by an individual) and participation (involvement in a life situation), and additional information on severity and environmental factors. As ICF emphasizes function instead of disease, it is applicable in most of the health conditions, across various cultures, age groups, and genders.[12] The WHO-DAS was replaced by the WHO Disability Assessment Schedule II (WHODAS-II) and then WHODAS 2.0 to be compatible with the ICF. It addressed behavioral limitations and restrictions to participation experienced by an individual, independently of the medical diagnosis.[13],[14],[15] Its items correspond directly with ICF's “activity and participation” dimension, which is applicable to all health condition. Work is underway to develop an additional module for bodily impairments.[16] Furthermore, efforts are on to develop a version of the WHODAS 2.0 for children and youth.

  Disability in the Classificatory Systems of Mental Disorders Top

Mental health is the only field of medicine where disability and impairment are not only seen as consequences of disease (coded as ICF) but also as an important criterion for establishing a diagnosis (that are coded in the International Classification of Disease, Tenth Edition [ICD-10]). Therefore, disability and functioning are at the same time part of two separate and theoretically complementary classification systems: the diagnostic system and its consequences on functioning and activity. For example, mental retardation/intellectual disability is a single entity or condition, which is classified at the same time in both systems.[17] This is unlike the diagnostic criteria for the majority of medical disorders. For example, the diagnosis of diabetes mellitus is made based on the fasting levels of blood sugar and not based on complications of diabetes mellitus.

Classification of Disability in Diagnostic and Statistical Manual of Mental Disorders

From Diagnostic and Statistical Manual of Mental Disorders Third Edition (DSM-III) to DSM-IV-TR, the disorders were classified in Axis I and II, whereas their outcomes were measured as a global activity index on Axis V where the clinicians assessed patients' overall level of functioning during illness. However, a major overlap existed across both coding domains, as impairment of activity/functioning was a part of main diagnostic criteria as well as Axis V rating. The combination of symptoms and functioning in the same scale resulted in inaccurate measurement of functional impairment itself. As the Global Assessment of Functioning scale specifically excluded impairment in functioning due to physical or environmental limitations, its conflation of symptom severity and functional impairment into a single global assessment score decreased its construct validity.[18]

The WHO, on the other hand, conceptualized limitations in activities and behaviors and restrictions on participation in life and society as exemplifying a final common pathway through which all disorders, medical or psychiatric, result in disability. The DSM-5 has advocated WHODAS 2.0 as the measure of disability for routine clinical use.[19]

Classification of Disability in International Classification of Disease, Tenth Edition

The weight of the functioning/disability domain in psychiatric diagnosis is lower in ICD-10 than in DSM, as it is mainly used for subclassification of disorders according to severity. For example, distinction between mild depressive episode (F32.0) and moderate depressive episode (F32.1) depends on the “difficulty in continuing with ordinary activities.”[20] Recent international studies provide evidence that even when using minimum criteria set in ICD-10 to make a diagnosis of depressive episode, those who met the criteria had disability comparable to other chronic conditions.

The International Advisory Group for the Revision of ICD-10 Mental and Behavioural Disorders recommended against having functional impairment/disability as part of the inclusion criteria for disorders in general, as it is generally relatively nonspecific with respect to the diagnosis. The group also suggested providing definitions of functional impairment and disability that are consistent with ICF and refers readers to the ICF for additional information on the classification of functional status.

To be used alongside ICD-10 classification of mental disorders, the evaluation of disability has been adapted from ICF in several ways. An axis on functional disability was included at the multiaxial presentation of the ICD-10 for use in adult psychiatry. This Axis II of ICD was conceptualized in accordance with the principles of ICIDH and it served to rate disabilities in relation to the tasks and roles expected from the individual in his/her sociocultural setting. The ICIDH covers specific areas of functioning clustered in four main categories – Personal Care, Occupation, Family and household, and Functioning in a broader Social Context. These four categories contain subcategories adding to 14 areas of functioning. Originally, these areas were measured using the WHO Short Disability Assessment Schedule.[21] A new and expanded version of the WHODAS-II was developed to assess disability in any medical condition, worldwide, including mental health disorders following the ICF approach.[22] ICF core sets for psychiatric disorders are underdevelopment. For example, the Brief ICF Core Set for depression includes a total of 31 categories from an initial set of 323; with 9 on body functions, 12 on activities and participation, and 10 on environmental factors. A core set for bipolar disorders has also been developed.[23]

  Conflation of International Classification of Disease and International Classification of Functioning, Disability and Health Top

Despite the acknowledgment of the disease and its impact on functioning,[24] the concept of cooccurrence has not been utilized optimally.[25] Describing and understanding the relationship between disease and functioning requires the use of two of the World Health Organization's classifications systems: the ICD[26] and the ICF.[3] The ICD and the ICF classification systems are contemplated by the WHO to augment one another 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),[27] 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 TAG, which consults with each of the TAGs regarding how to deal with functioning properties for their assigned ICD entities.

In the ICF, “functioning” is an ambient term for body functions, body structures, and activities and participation. In the ICD Content Model, functioning properties only include the activities and participation component of the ICF. Activity is described in the ICF as the “execution of a task or action by an individual,” while participation is described as “involvement in a life situation.”[3] Activities and participation are important in describing the impact of a disease because they capture the broad and relevant aspects of activity and involvement with society and life in general. Hence, an ICD code would have a corresponding value set of functioning properties.

Before ICD-11 is completed, functioning properties will need to be ascribed for each ICD code. This task is being done and coordinated using the web-based International Collaborative Authoring Tool (iCAT) by content experts worldwide in three steps: (i) selection of functioning properties provided in iCAT, (ii) 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 (iii) 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.[28]

Intrinsic limitations of the International Classification of Functioning, Disability and Health

The ICF presents the following limitations that affect its implementation in clinical practice:

  1. There is lack of definition and development of the domain of personal factors such as coping strategies or skills, and personality traits, which are the goal of most psychosocial intervention
  2. Nowadays, most researchers enforce concepts such as recovery from mental illness as they involve elements beyond symptoms and functioning, and it entails a more optimistic view of the mental illness, its treatment, and its outcomes. This prospect is poorly included in the ICF by focussing on the deficit model
  3. A universal model of capacity is needed in the field of mental illness. As long as the ICF does not explicitly develop a universal taxonomy of capacities, it would be difficult to implement the ICF model as the framework for classifying abilities and disabilities. Methodologically, useful and flexible instruments are required to capture both disabilities and capabilities. The ICF-related instruments seem to have difficulties in capturing relevant domains for the understanding of mental disorders such as personal factors and contextual barriers[25]
  4. Accessibility of ICF – The ICF as an instrument which is currently more accessible to medical doctors than other mental health practitioners and allied professionals because ICF is being conceptualized on the biopsychosocial model. The medical doctors with their training being in biology and pharmacology, they may be more reluctant to use it
  5. The implementation of the ICF in the field of psychiatry is difficult as the field is dominated by medical model and strongly influenced by pharmaceutical industry.[25] To overcome these limitations, Kostanjsek et al. suggested the joint use of the ICD-10 and the ICF. Therefore, the integration of the ICF into the ICD-11 could become the gateway for the actual implementation of the ICF in different clinical settings, including psychiatry.[29]

  Conclusions Top

Recognition and classification of disability is crucial for mental health professionals as large number of psychiatric disorders run a chronic course and lead to significant impairment. As a signatory to the UNCRPD, India has enacted Rights of Persons with Disability Act (2016) and Mental Health Care Act (2017). Hence, a large number of persons with disability are expected to contact mental health professionals for assessment and certification. This warrants the availability of valid instrument for assessment and quantification of disability. The ICF provides an internationally recognized basis for the assessment of disability on different domains and it represents a new way to think about health and about functioning and a move away from the acute disease model which has been the basis for understanding and practice by health providers.

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 toward a concerted planning of care ultimately benefiting the patients. 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. Thus, ICF may be very useful in helping to target the resources appropriately.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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