The process of preparing the chapter on mental and behavioural disorders of the ICD 11

The tenth edition of the International classification of diseases and related health problems (ICD) is currently the international standard for collecting information on diseases. The member countries of the World Health Organisation (WHO) agreed to use the ICD as the reference for gathering and conveying information on diseases with very different objectives. Firstly, to monitor epidemics, threats to public health and to analyse the disease burden. Secondly to assess the extent to which public health objectives are met. It is also used to define the obligations of the WHO member states in terms of the provision of free or subsidised health services to their populations, and is a key instrument in enabling access to the appropriate health services. It enables communication between health system users (clinical professionals and researchers, patients, families, managers, etc.). Finally, it is an essential element for establishing care and clinical practice standards and facilitating research into more effective treatments and prevention strategies. The descriptive focus, based on diagnostic criteria defined by the WHO's ICD-10, and the more recent versions of the DSM, has been widely accepted by mental health professionals. The process of preparing the chapter on mental and behavioural disorders of ICD-11 is in its initial stages. Below we summarise the phases and procedures that have been followed in this process.

The WHO view the current revision of the ICD as an opportunity to improve the clinical utility of the classification.¹ Several objectives of the revision of ICD-10 that will become ICD-11 have been outlined in the area of mental and behavioural disorders. Firstly, the WHO member states will be provided with a better tool to help reduce the disease burden of mental and behavioural disorders. Secondly, healthcare professionals will be given better tools to identify people in need of mental health services, at the point where it is most likely that there will be effective treatment available.

The process to develop ICD-11 started in 2007 with the designation of the international advisory committee to revise the chapter on mental and behavioural disorders of ICD-10. Then, the WHO, on the advice of said committee, allocated the various members of the working groups for the revision of certain aspects of the classification. Working groups of experts from many disciplines and from all over the world have been formed. These groups are in charge of performing a review of the available literature and sources of relevant data for decision-making, and completing the information required for the various components of the diagnostic guidelines and clinical descriptions. Each working group was asked to prepare the necessary materials to complete these guidelines in a common format for all the disorders and cover the following aspects for all the diagnostic categories; category name, brief definition, inclusion terms, exclusion terms, essential (required) features, boundary with normality, boundary with other disorders (differential diagnosis), qualifier/subtype codes, course features, associated clinical presentations, culture-related features, developmental presentations and gender-related features.

The proposals of the working groups have been received and included by the WHO's Department of Mental Health and Substance Use in Geneva, who have been in charge throughout of coordinating this laborious process.

A central aspect in the development of ICD-11 has been to promote and facilitate collaboration with the different sectors that use the classification system. These include ministerial representatives, organisations of health professionals (psychiatrists, primary care doctors, neurologists, psychologists, social workers, nurses and public health experts), users, families and caregivers. With a view to making the proposals of groups of experts available to the scientific community, clinicians and the general public as quickly as possible and thus ensure the most open possible process of external consultation, the beta draft of all the categories and definitions of ICD-11 is available on the WHO website: http://apps.who.int/classifications/icd11/browse/f/en. Similarly, the different professional, user and governmental organisations have been formally requested to submit their comments to the draft.

In parallel with these activities, the Department of Mental Health and Substance Use designed a series of specific studies with novel methodologies with the aim of testing various aspects of the new classification proposal. The first were the formative studies in which international surveys were conducted between professionals to ask their opinion on specific aspects of the classification, its use in clinical practice and their perception of the need for changes to the ICD-10. Surveys were also designed to discover how clinicians conceptualise the existing relationships between the different mental disorders and their classification.² The information obtained through these studies is shown in the meta-structure of ICD-11, which was published very early on in the classification process.

Evaluative field studies were then initiated. Among these, the studies based on clinical vignettes are worthy of note for their novel methodology. These are international studies, implemented simultaneously in different languages that use common materials in the form of vignettes, with a description of clinical cases in which the presence is selectively controlled in the description of various features that are relevant for diagnosis. They are used to clarify the decision-making process using the new guidelines for clinical diagnosis of ICD-11 comparing them with those of ICD-10.³

A second group of ecological implementation studies are those conducted on clinical devices through the network of centres set up for field studies around the world. Noteworthy among these is the project on primary care devices led by Prof. Goldberg, which focuses on evaluating the new proposals for defining disorders that frequently appear in these devices.⁴ In addition, there are clinical field studies currently underway in 18 countries to assess the proposals for the classification of psychotic, affective and childhood and adolescent onset disorders. Their objective is to evaluate relevant aspects for the clinical utility of the new proposals; particularly the ease-of-use of the new proposals, diagnostic agreement between evaluating clinicians, the frequency with which the clinician treats patients with similar symptoms, degree of patient representativeness, trust in the diagnosis and finally, the level of “help” offered by the clinical guidelines.

The WHO has formed the so-called global clinical practice network to serve as a basis for the activities of dissemination and consultation of this ICD revision process, and to implement some of the abovementioned field studies. Over 14,000 professionals from more than 150 countries are registered on this platform.⁵ Of these, 45% are registered in English, 15% in Chinese and 10% in Spanish. The network is still open and can be accessed by registering at https://gcp.network. This network has proven an innovative route not only for disseminating information on new classification proposals, but also for recruiting clinicians from very diverse geographical and cultural areas to participate in many of the abovementioned field studies.

Since the start of the process for preparing the chapter on mental and behavioural disorders of ICD-11, the WHO has no longer sought to reach a consensus among only a small group of experts, as was the case for previous versions of the classification. This time, they have increased the number and multicultural and multidisciplinary representation of the experts that form the working groups. They have also sought to ensure at all times that these groups are represented by professionals working in middle and low income countries. Likewise, they have made special efforts to involve government, professional and clinical institutions from countries in which previous versions of the classification have not been adequately implemented or used. An example of this in the current process is the institutional support of professional representatives and experts from China. They have considerably added to the number of participants on the global clinical practice network, and have very actively disseminated the entire process of preparing ICD-11 among the mental health professionals and government bodies involved in mental health care in China. The efforts of the scientific community have also been outstanding in preparing proposals to present the activity of the working groups and the field studies to the general scientific community in the form of articles published in peer-reviewed journals, to ensure the necessary transparency of the process, enable critical analysis of the proposals and contribute to the debate on aspects that are very relevant for daily clinical practice. Three hundred and thirty-eight articles have been published to date, covering different aspects of the entire process of preparing the new classification.

As a result of all these activities, we are confident that the classification proposals put forward and the new structure chosen for presenting each category in the diagnostic guidelines and clinical descriptions of ICD-11 will improve the clinical utility of the manual, provide clear organisation and consistent information for all the various disorders and that it will be flexible enough to accommodate cultural variations and the judgement of clinicians. It is the objective of the work plan to complete the process of revising the chapter during the first half of 2018 and submit it for approval to the WHO together with the chapters on the remaining diseases covered under this international disease classification system.