ICD-11 Revision of Mental Disorders: the Global Standard for Health Data, Clinical Documentation, and Statistical Aggregation

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Even before the COVID-19 pandemic, the number of individuals with mental health conditions in the WHO European Region stood at over 110 million people, equivalent to more than 10% of the population.^1,2 Moreover, 140,000 lives are lost each year in the Region to suicide, an unacceptably high figure that includes an increasing number of young people.³ Comorbidity with other non-communicable diseases (NCDs)⁴ and with communicable diseases such as tuberculosis^5,6 and HIV⁷ is frequent, with mental health conditions sharing many of the same risk factors. Yet, out of all those in the European Region with the most common mental health conditions – depression and anxiety – the proportion receiving even basic care and support is at best a third, and as low as 5-10% in some European countries.^1,2

The COVID-19 pandemic has revealed to an even greater extent the vulnerability of public health systems to health emergencies, particularly related to disruptions to mental health services. It has underscored the need to integrate mental health into present and future preparedness and response strategies.

The WHO European Programme of Work (EPW), 2020–2025: «United Action for Better Health in Europe», adopted in Copenhagen last September at the 70th session of the WHO Regional Committee for Europe, consists of four flagship initiatives that complement its three core priorities. They are intended as accelerators of change, mobilizing around critical issues that feature prominently on the Member States’ agendas. One of these four flagship initiatives is the establishment of a Mental Health Coalition at the European level. The upcoming World Health Assembly 2021 will devote considerable attention to mental health as a crucial part of a whole-of-society approach and universal health coverage, and to the WHO’s capacity to strengthen its work on mental health at global, regional and country levels, through the updated Mental Health Global Action Plan for 2013-2030.

With the ICD-11 approval by the World Health Assembly in May 2019, after more than a decade of intensive work, the transition from ICD-10 to the new ICD-11 for all Member States of the WHO has officially begun. Member States will be able to begin reporting health statistics using the ICD-11 as a framework from 1^st January 2022.

The development of the ICD-11 chapter on Mental, Behavioural and Neurodevelopmental Disorders has been informed by several core principles, including clinical utility, international, transcultural and global applicability, and a multidisciplinary approach.⁸ Clinical utility was considered to be among the most important elements because it would determine the system’s acceptance by practitioners and therefore influence its role in treatment design and various administrative and social functions, including pensions and legal determinations.⁹

The Clinical Descriptions and Diagnostic Guidelines (CDDG) for ICD-11 Mental, Behavioural and Neurodevelopmental Disorders has followed this same approach based on a strong scientific methodology.^10,11 It demanded collaboration among hundreds of international experts in specific fields and extensive collaboration with WHO Member States, funding agencies and professional and scientific societies. This was the most extensive global, multilingual, multidisciplinary and participative process ever undertaken for the development or the revision of a classification system for mental disorders. It included more than 15,000 experts from 155 countries, representing approximately 80% of the world’s population.¹²

Prime features of the development of the ICD-11 CDDG were: 1) the systematic gathering and distilling of data and information; 2) a lifespan approach rather than a cross-sectional conceptualization; 3) a focus on more pragmatic indices, including long-term comorbidity and disability. The sources and the final text of the Diagnostic and Statistical Manual of Mental Disorders, 5^th Edition (DSM-5) were also carefully reviewed. While there are considerable differences between the ICD-11 and the DSM-5, these are substantive and intentional rather than accidental, unnecessary or unsupported by data.

Comorbidity is considered to be one of the most problematic issues in modern classification systems along with the excess fragmentation of nosological entities, sometimes referred to as the ‘atomization of psychopathology’.^13,14 Some of the changes in the ICD-11 were made to decrease this artificial comorbidity, using broader categories like Bodily Distress Disorder and dimensional approaches, such as in Personality Disorder. A developmental approach to mental disorders has also unified the classification of child and adult presentations, with attention to presentations in older adults. This has facilitated the emphasis within the ICD-11 on a recovery-based viewpoint. Whereas the ICD-10 used a dichotomy between organic and non-organic mental disorders, such a rigid conceptualization was avoided in the 11^th Revision.

A substantially new structure for the subclassification of mental disorders was followed (Table 1), which is also broadly compatible with the structure of the DSM-5. Regarding the disorders related to sexuality, paraphilic disorders (referred to as disorders of sexual preference in the ICD-10) were retained in the chapter on mental disorders. Sexual dysfunctions and gender incongruence (called Gender Identity Disorders in the ICD-10) were moved to a novel chapter specifically created for conditions related to sexual health.^11,15

Several new nosological entities were created on the basis of data that had emerged since the approval of the ICD-10. Examples of such new entities are Bipolar II Disorder, Body Dysmorphic Disorder and Hoarding Disorder. Another unique characteristic is the adoption of a dimensional approach; in particular, it is notable that this was used not only for personality disorders but also for psychotic disorders. The extent to which this revolutionary change will be adopted by practitioners and its impact on reported data remain to be seen.

 

Table 1. ICD-11 Chapter on mental, behavioural and neurodevelopmental disorders: disorder groupings

Neurodevelopmental disorders

Schizophrenia and other primary psychotic disorders

Catatonia

Mood disorders

Anxiety and fear-related disorders

Obsessive-compulsive and related disorders

Disorders specifically associated with stress

Dissociative disorders

Feeding and eating disorders

Elimination disorders

Disorders of bodily distress and bodily experience

Disorders due to substance use and addictive behaviours

Impulse control disorders

Disruptive behaviour and dissocial disorders

Personality disorders

Paraphilic disorders

Factitious disorders

Neurocognitive disorders

Mental and behavioural disorders associated with pregnancy, childbirth and the puerperium

Psychological and behavioural factors affecting disorders or diseases classified elsewhere

Secondary mental or behavioural syndromes associated with disorders or diseases classified elsewhere

 

Cultural applicability^16-18 was also of prime importance and therefore flexibility in clinical judgement was allowed, facilitating the incorporation and utilization of local knowledge when it can aid in clinical decisions.

The ICD-11 represents the first revision of the ICD for nearly 30 years and reflects both an unprecedented effort and advances in methodological quality. With the end product now in place, the most difficult phase, that of rigorous implementation should begin, with a focus on training and on adoption of the ICD-11 in training and educational curricula.

Authors contribution: Melita Vujnovic and Olga Manukhina conceptualized the paper and provided feedback on the manuscript; Konstantinos N. Fountoulakis and Pavlos N. Theodorakis drafted the first version of the manuscript; Geoffrey M. Reed revised and edited the manuscript. All authors approved the final version of the manuscript.

Funding: The research was carried out without additional funding.

Conflict of Interests: The authors report no conflicts of interest.

About the authors

Melita Vujnovic

WHO Country Office in the Russian Federation

Author for correspondence.
Email: vujnovicm@who.int
Russian Federation, Moscow

Olga Manukhina

WHO Country Office in the Russian Federation

Email: manukhinao@who.int
Russian Federation, Moscow

Geoffrey M. Reed

Columbia University Vagelos College of Physicians and Surgeons

Email: gmreed@mac.com
United States, New York

Pavlos N. Theodorakis

WHO Country Office in the Russian Federation

Email: theodorakisp@who.int
Russian Federation, Moscow

Konstantinos N. Fountoulakis

Aristotle University of Thessaloniki

Email: Kostasfountoulakis@gmail.com
Greece, Thessaloniki

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