A conceptual framework for the revision of the ICD‐10 classification of mental and behavioural disorders

The World Health Organization (WHO) is in the process of revising the International Classification of Diseases and Related Health Problems, currently in its tenth version (ICD-10). The WHO Department of Mental Health and Substance Abuse is responsible for the revision of the ICD-10 classification of mental and behavioural disorders, within the overall framework of the ICD revision effort. The purpose of this article is to articulate WHO's perspective and priorities for the ICD-11 mental and behavioural disorders classification, based on the initial period of work by the International Advisory Group for the Revision of ICD-10 Mental and Behavioural Disorders. The WHO is a specialized agency of the United Nations established in 1948, whose mission is the attainment by all peoples of the highest possible level of health. The WHO has explicitly defined mental health as a part of health from its inception. WHO's constitution 1, ratified by all 193 current WHO member countries, enumerates its core responsibilities, which include: establishing and revising international nomenclatures of diseases, causes of death and public health practice; and standardizing diagnostic procedures as necessary. Classification systems are therefore a core constitutional responsibility, which the WHO does not have the option of devolving to other parties. The ICD is the oldest, most central, and most historically important of WHO's classification systems. The purpose of the ICD is to serve as an international standard for health information to enable the assessment and monitoring of mortality, morbidity, and other relevant parameters related to health. The WHO is the only organization with the ability to secure global cooperation and international agreement on these issues and is therefore in a unique position to initiate and promote global health standards. WHO's classification systems are the basis for tracking epidemics and disease burden, identifying the appropriate targets of health care resources, and encouraging accountability among member countries for public health at the population level. WHO's classification systems are also among the core building blocks for the electronic health information systems that are of increasing importance in many countries. As a common classification framework, the ICD has fostered global communication and information exchange. At the clinical level, classifications enable communication among health professionals, their patients, and the health systems in which they work, and facilitate the training of health professionals across countries and cultures. WHO classifications also serve other sectors, including health policy makers and payers of health care services, the judicial system, and governments. Because the ICD plays such a crucial role in the international health community, it is critical that it be based on the best available scientific knowledge and that it keep pace with significant advances in health care that have the potential to improve its reliability, validity, and utility. The ICD-10 was approved by the World Health Assembly in 1990 and published in 1992 2, making the current period the longest in the history of the ICD without a major revision. The World Health Assembly, comprised of the health ministers of all WHO member countries, has directed WHO to revise the ICD-10. The technical work associated with the preparation of ICD-11 in scheduled for completion in 2013. It is envisioned that the World Health Assembly will approve the ICD-11, covering all diseases, disorders, injuries, and health conditions, in 2014. Within the context of the overall revision framework, the revision of ICD-10 Chapter V (F), Mental and Behavioural Disorders, is being undertaken. Conducting the Chapter V revision within the overall context of ICD revision facilitates coordination with classification of other disorders, including neurological and other medical conditions that are frequently comorbid with mental and behavioural disorders. The inclusion of mental and behavioural disorders alongside all other diagnostic entities in health care is an important feature of the ICD, facilitating the search for related mechanisms of etiology, pathophysiology, and comorbidity of disease processes and providing a solid basis for the parity of psychopathology with the rest of the medical system for clinical, administrative, and financial functions in health care. To assist with the current revision of the ICD mental and behavioural disorders classification, the WHO convened a high-level International Advisory Group in January 2007, with the primary task of advising on all steps leading to the revision of the chapter on mental and behavioural disorders in ICD-10 in line with the overall revision process. The Advisory Group includes experts from all WHO regions, as well as representatives of international associations of multidisciplinary mental health professionals. The Advisory Group has considered a number of important foundational issues on which specific revision activities in the next phase of work have to be based, achieving a fairly remarkable degree of consensus in its perspective. The following sections describe some of the basic conceptual issues considered and recommendations made by the Advisory Group. One of the earliest questions confronting the Advisory Group was how mental disorders should be defined. This definition of mental disorders sets the boundaries for what is being classified, and has enormous consequences for public health action, for governments, for health systems, and for research. For example, how mental disorders are defined affects epidemiological estimates of their prevalence, the legal protections available to people affected by them, the structure, functioning, and payment mechanisms for mental health service systems, and evaluation of the outcomes of mental health interventions. The clinical descriptions and diagnostic guidelines for ICD-10 mental and behavioural disorders 3 define a mental disorder as “a clinically recognizable set of symptoms or behaviours associated in most cases with distress and with interference with personal functions”. The definition of mental disorders found in DSM-IV-TR 4 is similar, and has not changed since DSM-III 5: “a clinically significant behavioral or psychological syndrome or pattern that occurs in an individual and that is associated with present distress … or disability or with a significantly increased risk of suffering death, pain, disability, or important loss of freedom… [that is] considered a manifestation of behavioral, psychological, or biological dysfunction in the individual”. The Advisory Group recommended that ICD-11 use the same definition for mental and behavioural disorders used in ICD-10, favoring its simplicity over the more complex definition used in DSM. The Advisory Group also noted that the DSM-IV definition has a different relationship to issues of functional status than does the ICD-10 definition, a topic that is explored further in a later section of this article. Due to their broad importance, the WHO considers that classifications should be designed in consultation and, where possible, collaboration with stakeholders. The first direct stakeholder group to which WHO considers itself accountable during the ICD revision, and WHO's primary constituency, consists of the governments of WHO member countries. These governments have specific interests in ICD for several reasons. First, governments are asked to report morbidity and mortality statistics to the WHO according to the ICD classification. Second, governments want health classification to reflect their particular perspectives and priorities for health care. For example, they may not share the assumption that categories of mental illness are both culturally universal and adequately defined by existing categories. Third, governments are interested in the ICD because diagnostic classification provides a large part of the framework that defines the government's obligations to provide free or subsidized health care, social services, and disability benefits to its citizens. Fourth, the interests of governments are aligned with the global public health priorities that are the reason for WHO's existence: they want help in reducing the disease burden of mental and behavioural disorders. Finally, any changes to the existing ICD as it is used by member countries may involve the commitment of substantial resources to change existing record systems, health survey instruments, administrative procedures, health policy, and even legislation related to diagnosis. Governments may also have to make large investments in training health professionals to use the new system. The second important group of direct stakeholders in the revision of the ICD mental health classification is health care professionals. Psychiatrists are not the only professionals involved in the diagnosis and classification of mental disorders. Only a very small percentage of individuals with mental disorders will ever see a psychiatrist. Psychiatrists are in relatively generous supply in high-income countries: about 10.5 per 10,000 population 6. But the proportion of the world's population that live in these countries is small, only about 15%, and declining. By contrast, there is less than 1 psychiatrist per 100,000 population in low-income countries, which are home to nearly half the world's people. In lower-middle income countries, there is an average of about 1 psychiatrist per 100,000 population, and an average of 2.7 in upper-middle income countries 6. Therefore, psychiatrists cannot be seen as the primary users and the sole professional constituency for the classification. Other professional groups should also have a meaningful and proportionate role in the process. This includes other mental health professionals such as psychologists, social workers, and psychiatric nurses. It also includes other physician groups, especially primary care physicians, as well as lay health care workers who deliver the majority of primary and mental health care in some developing countries. For this reason, representatives of international professional associations representing these groups have been included in the Advisory Group from the beginning. Geographic and linguistic diversity must also be addressed carefully in creating mechanisms for participation, as in the past it has generally been professionals from wealthier, usually Anglophone, countries who have been most easily able to travel and participate in meetings conducted in English. The influence of the pharmaceutical industry on some groups of professionals must also be addressed seriously. In order to avoid undue influence, the WHO considers that it is imperative to examine carefully possible conflicts of interest among participants in the revision of mental disorders classification and diagnostic criteria. For the mental disorders classification in ICD, the WHO recognizes the users of mental health services and their family members as a third direct stakeholder group. The user community in mental health has been increasingly aligned with the disability rights movement, adopting the motto of ‘Nothing about us without us!’, rejecting what they see as medical paternalism, and demanding to be consulted about the decisions that affect their lives. The ICD revision process must encompass substantive and serious opportunities for participation of user groups, not just symbolic and ritualistic gestures. At the same time, service user and family organizations are not monolithic, but rather characterized by a wide diversity of perspectives and opinions. Opportunities must be for that are and that they to the revision process and are more than a of specific categories of mental disorders is an assumption in ICD-10. 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