Year : 2018 | Volume
: 34 | Issue : 5 | Page : 17--22
Mood disorders in the international classification of Diseases-11: Similarities and differences with the diagnostic and statistical manual of mental Disorders 5 and the international classification of Diseases-10
Department of Psychiatry, Postgraduate Institute of Medical Education and Research, Chandigarh, India
Prof. Subho Chakrabarti
Department of Psychiatry, Postgraduate Institute of Medical Education and Research, Sector-12, Chandigarh - 160 012
|How to cite this article:|
Chakrabarti S. Mood disorders in the international classification of Diseases-11: Similarities and differences with the diagnostic and statistical manual of mental Disorders 5 and the international classification of Diseases-10.Indian J Soc Psychiatry 2018;34:17-22
|How to cite this URL:|
Chakrabarti S. Mood disorders in the international classification of Diseases-11: Similarities and differences with the diagnostic and statistical manual of mental Disorders 5 and the international classification of Diseases-10. Indian J Soc Psychiatry [serial online] 2018 [cited 2021 Jan 25 ];34:17-22
Available from: https://www.indjsp.org/text.asp?2018/34/5/17/245825
This article briefly summarizes the issues relevant to the classification of mood disorders, that is, depressive and bipolar disorders in the forthcoming 11th Revision of the International Classification of Diseases and Related Health Problems (ICD-11). It is almost exclusively concerned with the clinical descriptions and diagnostic guidelines (CDDG) version of the ICD-11, which is its most commonly used version. Other versions, such as the primary-care version have not been covered.
Changes Made to the Chapter on Mental and Behavioral Disorders in the International Classification of Diseases-11 Revision
Much like the rest of the sections on mental and behavioral disorders in the ICD-11 draft, changes made to the structure and content of the section on mood disorders had to take into account several key issues influencing the diagnosis of these disorders. These considerations included the growing burden of mood disorders, the diversity of their clinical features, cross-cultural variability in symptoms, and the difficulties of distinguishing these disorders from other conditions as well as normal variations in mood.,,, As a part of its mandate, the World Health Organization (WHO) has placed considerable emphasis on clinical utility and global applicability as the chief orienting principles for any revisions suggested. In addition, the scientific foundations of the classification had to be maintained by basing it on the best available evidence; its cross-cultural validity had to be ensured by factoring in cultural differences in presentation and harmonization with the Diagnostic and, close agreement with the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) had to be made certain by bringing diagnostic descriptions in accordance with the latter classification. These principles applied equally to the section on mood disorders as they did to the rest of the revision.
According to the working definition adopted by the WHO Department of Mental Health and Substance Abuse, clinical utility of a classification (or a mental disorder category) included its value in communication among users, features relevant to its implementation in clinical settings such as accuracy of descriptions or feasibility of use, and its usefulness in aiding clinical decision-making., The developers of the ICD-11 draft were acutely aware of the limitations in the clinical usefulness of existing classifications.,, Therefore, the ICD-11 revision, more so than the DSM-5, made clinical utility the guiding principle at all stages, from evidence review to content formation to examining the utility of draft versions in field trials. Simultaneously, the ICD-11 classification tried to ensure that clinical utility went hand-in-hand with empirical support for the classification and its constituent categories.
Unlike the different DSM classifications which have relied on operational diagnostic criteria, the ICD-10 had adopted a prototype-based approach, which was based on definitions and diagnostic guidelines for each category. This was because prototype-based approaches were considered to be more congruent with human cognitive processes, while being as reliable as criteria-based approaches. Moreover, prototype-based approaches appeared to be preferred by users, and thus, enhanced the clinical utility of the classification. However, the information about diagnostic categories in the ICD-10 had varied a great deal across the disorders compromising its clinical utility. Hence, the ICD-11 CDDG not only placed a lot of emphasis on including a greater amount of clinically relevant information for each diagnostic group, but also on making sure that information included was consistent and uniform across categories. Nonetheless, it adopted a flexible approach to diagnosis, which avoided complex criteria and somewhat arbitrary thresholds for diagnosis. Such a format has always been the preferred choice of all mental health professionals globally.,,
The working groups for different disorders including the mood disorders were also fully cognizant of the cross-cultural variability in presentations of different psychiatric disorders as well as the diverse ways, in which cultural factors influenced the diagnostic process., Therefore, a conscious effort was made to include a greater amount of information on cultural aspects of presentations of different disorders, a feature which was somewhat lacking in the ICD-10. Consequently, all diagnostic categories in the ICD-11 draft contain information on several aspects including the definition, diagnostic guidelines, boundaries with normality and other disorders, developmental presentations, typical course, comorbidities, and culture- and gender-related attributes.
To improve the global applicability of the ICD-11 further, the WHO International Advisory Group and all WHO Working Groups included members from all WHO global regions with a high proportion of representatives belonging to low- and middle-income countries. All field testing of proposed categories has been conducted globally and in several languages. Finally, the WHO intends to publish the ICD-11 classification in all official languages of the WHO.,
Efforts to harmonize the ICD-11 revision with the DSM-5 classification were the focus of the “Harmonization Group.” As a result of these efforts, a high degree of similarity between the overall structure of DSM-5 and the proposed linear structure for the ICD-11 draft has been achieved. Both classifications have accepted an organizational meta-structure, which groups disorders into similar clusters based on eleven possible validators relating to etiology, clinical manifestations, course, and outcome. Field studies of the proposed linear structure of the ICD-11 have shown that it fits better than the ICD-10 with clinicians' views regarding the organization of disorders.
Other changes to the ICD-11 revision as a result of harmonization with the DSM-5 are similarities in codes and nomenclature. The ICD-11 classification will use a different coding structure from the ICD-10 and an expanded linear structure consisting of about twenty groups of disorders., Apart from this expansion, considerable re-structuring of the hierarchy has also been undertaken. There will be separate but adjacent blocks for depressive and bipolar disorders in the mood disorders section. Cyclothymia will be grouped under bipolar disorders and dysthymia under depressive disorders. The diagnostic label of “bipolar affective disorders” in the ICD-10 has been changed to “bipolar disorders” in the ICD-11 draft, and the section on bipolar disorders has been labeled as “bipolar and related disorders” which is identical to the DSM-5. However, unlike the DSM-5, the ICD-11 classification has retained the superordinate grouping of mood disorders, thus addressing the concerns about snapping the traditional link between depressive and bipolar disorders with the new arrangement.
Changes Made to the Categories of Depressive Disorders
Proposed changes to the guidelines for depressive and bipolar disorders in the ICD-11 draft suggest that these sections will be quite different from the ICD-10 and the number of changes will probably outnumber those included in the DSM-5. Nevertheless, much like the DSM-5, the ICD-11 revision has chosen a simpler form of classification of mood disorders. Definitions of all mood episodes are provided right at the beginning so that requirements for the labeling of a particular episode are clearly met. The number and pattern of mood episodes over time will determine the diagnosis of either depressive or bipolar disorders.
Although the ICD-10 had made a number of improvements to the diagnosis of depression, it had its fair share of problems. Its classification was complex and the unipolar-bipolar distinction was not clearly emphasized. The distinction between single and recurrent episodes was not supported by follow-up studies, which show that 50%–80% of depressive disorders are recurrent. Initial descriptions of depressive episodes were sketchy and only elaborated upon much later in the section. This resulted in a somewhat confusing organization that required users to move backward and forward to arrive at a diagnosis. Psychotic subtypes included catatonic symptoms in addition to delusions and hallucinations. On the basis of current evidence, catatonic symptoms need to be distinguished from psychotic symptoms as done in the DSM classifications.
To rectify some of these lacunae, the ICD-11 draft clearly sets out diagnostic guidelines for depressive episodes at the commencement of the section on depressive disorders. Significant changes made to the diagnostic guidelines for depression include the omission of reduced energy and fatigue from the essential features and their inclusion in a “neurovegetative” cluster. Although this is in line with definitions of depressive episodes in the DSM-5, the idea of specific clusters of depressive symptoms is unique to ICD-11 revision. Then again, requirements for a threshold of five symptoms, one of which is from the “affective cluster” are similar to the DSM-5 and somewhat different from the ICD-10. In addition, impairment of role-function has been added as an essential feature. In the ICD-10, functional impairment was not included in the definition of depression because of concerns about cultural factors confounding social performance. However, the ICD-11 mood disorders working group chose to include impaired role-function as an essential feature because of the evidence linking severity of depression with functional decline and the well-known fallacies of relying solely on symptom counts to diagnose depression.
Depressive disorders in the revision include single episodes and recurrent depressive disorders. Although a large proportion of those with single episodes suffer a recurrence rendering this distinction somewhat superfluous, the category of “single episode depressive disorder” was retained mainly because the overwhelming majority of clinicians in global surveys continue to use this category.,
The ICD-10 CDDG differentiated between mild, moderate, and severe depression on the basis of the number, type, and severity of symptoms along with their impact on functioning, though the latter was not an essential descriptor. Although validation studies of these three levels of severity are somewhat scarce and their results inconsistent, the severity subtypes have been retained because of their clinical and treatment utility. However, contrary to the ICD-10, the number of symptoms required to grade severity has not been specified, while the impact of severity on functional impairment has been made more apparent.
In marked contrast to the ICD-10, description of the subtypes with psychotic symptoms in the ICD-11 revision has been enlarged and catatonic symptoms omitted from these descriptions. This brings it in line with the DSM definitions of psychotic specifiers. In addition, the difficulties inherent in the assessment of psychotic symptoms including the unclear boundaries between such symptoms and “sustained preoccupations” have been mentioned. Another important development is the addition of a new subtype-“moderate depressive episode with psychotic symptoms.” This was done because the evidence linking psychotic symptoms and severity of depression was found to be equivocal. Therefore, the recommendation was to delink severity of depressive episodes from the presence of psychosis.
The DSM-5 has left it up to the clinician's judgment to decide whether responses to significant, but natural losses (such as bereavement, job loss, or breakups) amount to a depressive episode after considering the individual's personal history and cultural background. The removal of this so-called “bereavement exclusion” (BE) criterion, while diagnosing depression has turned out to be one of the most controversial and intensely debated changes incorporated in the DSM-5. BE was a part of the DSM-IV definition of depression. The evidence favoring the elimination of the BE requirement is equivocal.,, Rather, the lack of such an exclusion unnecessarily converts a normal and expected response into a pathological one. Thus, the definition of depression in the ICD-11 draft clearly specifies the conditions that need to be fulfilled before a diagnosis of a depressive episode can be made in aftermath of bereavement or other such significant yet normal losses.
The ICD-11 draft also includes a number of other qualifiers for single and recurrent depressive episodes. Some of these such as the remission and melancholia qualifiers were present in the ICD-10, although melancholia was referred to by the somewhat confusing term “somatic symptoms.” Others such as seasonal and perinatal-onset qualifiers are new, but based on good evidence and are also included in the DSM-5. A qualifier of significant import is the “depression with prominent anxiety symptoms” qualifier. This is similar to the “anxious distress” specifier of the DSM-5. Both are acknowledgments of the high prevalence of anxiety symptoms in depression as well as the prognostic and treatment implications of such symptoms for individuals with depression and prominent anxiety symptoms. The same qualifier also mentions that both a depressive disorder and an anxiety disorder can be diagnosed simultaneously if criteria are met for both disorders. Thus, unlike the ICD-10 (and perhaps even the DSM-5), the ICD-11 revision has removed the diagnostic hierarchy allowing depressive disorders to trump anxiety disorders. This is also consonant with the current evidence.
The ICD-11 draft also acknowledges the presence of comorbid subthreshold depressive and subthreshold anxiety symptoms by retaining the category of mixed depressive and anxiety disorder present in the ICD-10. The DSM-5 had excluded this category because of poor reliability in field trials. Nevertheless, mixed depressive and anxiety disorders are extremely common, particularly in primary-care settings and are associated with significant disability.,, Accordingly, the ICD-11 draft has not only included this category but also proposed more elaborate guidelines for its diagnosis. The new category now referred to as “mixed depressive and anxiety disorder” has been brought under the fold of depressive disorders. The distinction from normality and other mood and anxiety disorders (which was part of the ICD-10 requirements) has been clarified. In addition, essential features for diagnosis include a minimum duration of 2 weeks, further elaboration of the nature of depressive and anxiety symptoms, and the requirement for significant distress or impairment.
Finally, the category of dysthymic disorder contains much more elaborate diagnostic guidelines than the ICD-10. The emphasis on persistence of subthreshold depressive symptoms for a long time separates this condition from the more episodic varieties of depressive disorders. However, allowance has been made for the diagnosis of the highly prevalent condition of comorbid dysthymia and depressive disorders (double depression) when individuals meet diagnostic requirements for both disorders following the initial period of subthreshold symptoms required for the diagnosis of dysthymia. Dysthymia has also been more firmly linked to depressive disorders and distinguished from personality disorders by excluding older ICD-10 inclusion terms such as depressive personality disorder. Other requirements for its diagnosis are very similar to the DSM-5 apart from a few minor yet significant differences. For example, the requirement that the diagnosis of depressive disorder cannot be made in the first 2 years of the dysthymia serves to differentiate it from chronic, unremitted forms of major depressive disorder. On the other hand, a longer list of characteristic symptoms than the DSM-5 allows better identification.
Changes Made to the Categories of Bipolar and Related Disorders
Definitions of manic and hypomanic episodes in the ICD-11 draft are also more elaborate and precise. Thus, they are considerably different from the ICD-10 and closer to the DSM-5 descriptions. Apart from including typical manic symptoms that are significantly different from normal variations in mood, definitions of both mania and hypomania require the simultaneous presence of persistent changes in mood (euphoria, irritability, expansiveness, and lability) as well as changes in activity or energy. The addition of the increased activity/energy guideline represented a significant change from earlier versions of the ICD and the DSM. It was based on a substantial body of evidence, which indicates that excessive energy or overactivity are essential elements of manic or hypomanic presentations. Nonetheless, the requirement for the concurrent presence of changes in mood and activity levels has been criticized as being too restrictive. A recent study has indeed demonstrated that the use of this dyadic criterion in the DSM-5 reduces the prevalence of manic and hypomanic episodes by about half. Then again, others have disagreed about the inflexibility of this dual-criteria set and have downplayed their impact., Strangely enough, concerns have also been raised about the overdiagnosis of bipolar disorders because of the more inclusive definitions. However, these concerns appear groundless as another recent study has shown only a minor impact on the prevalence of bipolar disorders using the DSM-5 criteria. Another positive change has been the inclusion of an additional feature regarding effects of pharmacological treatment. This allows the diagnosis of bipolar disorder to be made as long as a full syndrome of mania or hypomania persists beyond the known effects of such treatment.
In contrast to the similarities in definitions of mania and hypomania, the ICD-11 revision and the DSM-5 differ a great deal regarding the definition of a mixed episode. DSM-5 has abandoned the category of a mixed episode and substituted it with a “mixed features” specifier. Although this change was ostensibly implemented to capture the more common subthreshold presentations of mixed states, it has been criticized for making the definition of mixed episodes more complicated. Moreover, the definition of “major depressive disorder with mixed features” in the DSM-5 is closer to definitions of mania and hypomania, rather than the traditional definition of mixed depression. The ICD-10 definition of mixed episodes emphasized the rapid alternation of prominent manic or hypomanic and depressive symptoms, rather than the simultaneous presence of full manic, hypomanic, or depressive syndromes. Although this definition appeared to be more in agreement with modern concepts of mixed states, it was neither too detailed nor too precise. The ICD-11 revision has adopted a similar definition of mixed episodes characterized by the presence of persistent, prominent, and rapidly alternating manic/hypomanic and depressive symptoms in a single episode lasting for at least 2 weeks. However, contrary to the ICD-10, it has provided additional details about contrapolar symptoms and episode-qualifiers.
In contrast to the ICD-10, the presence of at least one manic or mixed episode will be sufficient to make a diagnosis of bipolar I disorder in the ICD-11 draft. This is a much needed change based on substantial research data, which indicates that the occurrence of mania predicts the typical course of bipolar disorders and separates it from other mood and psychotic disorders. This also ensures that the diagnosis of bipolar I disorder in ICD-11 is compatible with the DSM, while added descriptions of the interepisodic course, suicidal risk, family history, and comorbidity are expected to add greater reliability to the diagnosis.
The inclusion of bipolar II disorder in the ICD-11 draft is perhaps the most conspicuous alteration that sets it apart from the ICD-10. The differentiation between the two subtypes of bipolar disorders has been accepted since the DSM-IV and is merited on the basis of differences in etiology, presentation, course, and outcome. The requirement of at least one hypomanic episode and one depressive episode will extend the similarity between definitions of bipolar II disorder in the DSM-5 and the ICD-11 revision. The emphasis on significant dysfunction and greater likelihood of treatment-seeking during depressive episodes is also justified given that bipolar II disorder may be equally if not more impairing than bipolar I disorder in certain aspects.,
Despite according recognition to bipolar II disorder, the ICD-11 revision has stopped short of including other categories from the bipolar disorders spectrum. There is accumulating evidence for the high prevalence of these spectrum disorders, together with the lack of detection in routine practice, poorer prognosis, and increased risk of conversion to threshold disorders. However, they were not included because of doubts about their validity as well as clinical utility, given the lack of external validation and controlled data on treatment-response.,
Episode qualifiers of bipolar disorders include those pertaining to remission, severity, psychotic symptoms, melancholia, comorbid anxiety, perinatal onset, seasonal pattern, and rapid cycling. Among these, “anxiety comorbidity” deserves special mention because much like in the case of depressive disorders, there is growing awareness of the high prevalence of anxiety pathology in bipolar disorders and the influence of this comorbidity on the course and outcome of bipolar disorders.
The guidelines for cyclothymia have been broadened and more clearly specified in the ICD-11 draft compared to the ICD-10. Suitable emphasis has been placed on persistent, largely subthreshold variations in mood which are associated with significant functional impairment. This brings the diagnosis in consonance with current notions of the construct as well as its definition in the DSM-5. In addition, incorporation of the necessity of monitoring these patients may help in timely recognition and intervention in the substantial proportion who convert to bipolar disorders.
Finally, the ICD-11 draft has devoted considerable attention to separating cyclothymia and other milder mood disorders from normal variations in mood. Similarly, the difficult differentiation of psychotic mood disorders from schizophrenia and schizoaffective disorder has been attempted to the fullest possible extent.
Conclusion: To Revise or Not to Revise
The million dollar question at the end of this long and large-scale effort of revising the ICD will be whether the exercise was a worthwhile one. Proponents will rightly point out the several much needed improvements that have been made to the earlier version, including the improvements made to definitions of different categories based on the current evidence, and the improved methodologies used for testing the utility and universal applicability of the revision. Critics will equally rightly claim, as they already have in the case of the DSM-5, that very little progress has been made toward a truly valid classification and that the endeavor has been mostly about repackaging old wine in new bottles. Both will perhaps have to wait for the verdict about its usefulness from actual users of the revised classification. With regard to the section on mood disorders, a definitive evaluation will only be possible once the final version of the revision is available. The draft version certainly has many heartening improvements as well as many unanswered questions about the changes that were made or those that were not made. Much of this might have to do with the deficiencies in the current status of research evidence, which will hopefully be resolved with time and future revisions. This brings us back to the question whether or not to revise existing classifications given the deficiencies in our extant knowledge. The thought-leaders of our profession seem to believe that it is necessary to persevere, but by tempering our expectations with pragmatism, by accepting the complexity of the task, and by avoiding undue pessimism., They rightly point out that while mental disorders may not yet be true disease entities, the distress associated with them and the great need to alleviate this suffering are real enough for us to persist. Therefore, (borrowing from William Hickson) – it is a lesson we should heed; if at first we do not succeed, we should try, try, and try again.
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