Indian Journal of Social Psychiatry

DEBATE/PERSPECTIVE/VIEWPOINT
Year
: 2018  |  Volume : 34  |  Issue : 5  |  Page : 11--16

Psychosis and related disorders in international classification of Disease-11 and their relationship to diagnostic and statistical Manual-5 and international classification of Disease-10


Abid Choudry1, Saeed Farooq2,  
1 Early Intervention, Worcester Health and Care NHS Trust, Forward Thinking Birmingham, Birmingham, England, UK
2 Early Intervention, Research Institute for Primary Care and Health Sciences, Keele University; Early Intervention, Staffordshire University; Research Institute for Primary Care and Health Sciences, Keele University, Keele, England, UK

Correspondence Address:
Dr. Abid Choudry
Worcester Health and Care NHS Trust, Forward Thinking Birmingham, Raddlebarn Road, Selly Oak, B29 6JB
UK

Abstract

The two main classification systems, International Classification of disease (ICD) and diagnostic and statistical manual (DSM) have recently been revised. The revision of DSM-IV by the American Psychiatric Association is complete and DSM-5 has already arrived. The draft ICD-11 diagnostic guidelines for mental disorders are nearly complete and will soon be published as ICD-11. In this article we will briefly discuss the challenges in classifying psychotic disorders, the revised classification of these disorders in ICD-11 and how this differs from ICD-10 and DSM-5. Several changes to the classification of schizophrenia and other psychotic disorders have been made to increase the reliability, clinical use and validity of the diagnostic classification which are considered here.



How to cite this article:
Choudry A, Farooq S. Psychosis and related disorders in international classification of Disease-11 and their relationship to diagnostic and statistical Manual-5 and international classification of Disease-10.Indian J Soc Psychiatry 2018;34:11-16


How to cite this URL:
Choudry A, Farooq S. Psychosis and related disorders in international classification of Disease-11 and their relationship to diagnostic and statistical Manual-5 and international classification of Disease-10. Indian J Soc Psychiatry [serial online] 2018 [cited 2019 Apr 23 ];34:11-16
Available from: http://www.indjsp.org/text.asp?2018/34/5/11/245839


Full Text



 Introduction



The two main classification systems, i.e., international classification of disease (ICD) and diagnostic and statistical manual (DSM) have recently been revised. The DSM-5 has already arrived, while the draft ICD-11 diagnostic guidelines for mental disorders are nearly complete. In this article, we will briefly discuss the challenges in classifying psychotic disorders, the revised classification of these disorders in ICD-11, and how this differs from ICD-10 and DSM-5.

There are number of challenges in the classification of psychiatric disorders, and classifying psychosis epitomizes these challenges. The nomenclature of the core category of schizophrenia is itself not universally acceptable. The Japanese classification has already renamed schizophrenia as “integration disorder.”[1] Translation of the word “schizophrenia” to Japanese “seishin-bunretsu-byo” means “mind-split-disease.” The new term to replace schizophrenia “togo shitchosho,” which means “integration disorder,” is considered more positive for users and carers. Whether changing the name of a diagnostic concept will have any effect on the stigma remains to be seen, but it highlights the challenges associated with the classification of psychiatric disorders.

Psychosis is a clinical syndrome, not a nosological entity. The term “psychosis” has been used for about 170 years[2] and still seems to serve a useful function as it is retained in the draft ICD-11 as well as DSM-5. The clinical syndrome is characterized by several “psychotic” symptoms such as delusions and hallucinations and lack of insight; however, a clearly operationalized definition of the term “psychosis” is still lacking.

 Issues Regarding Psychosis and Related Disorders in International Classification of Disease-10



The current construct of schizophrenia is derived from Kraepelin's formulation of dementia praecox in the late 19th century. Definitions of schizophrenia included in ICD-10 and DSM-IV are based on the Kraepelinian dichotomy focusing on its chronic course. Gradually, pathophysiological and etiological factors relevant to schizophrenia have become clearer.[3],[4]

The classical subtypes of schizophrenia provided a poor description of its heterogeneity with only the paranoid and undifferentiated subtypes being used more frequently[5],[6] in clinical practice; further, their longitudinal stability was found to be low. Moreover, the ICD-10 construct of schizophrenia was criticized for not adequately describing major psychopathological dimensions of the condition.[6] The DSM-5 as well as draft ICD-11 have replaced subtypes of schizophrenia with dimensional classification.

In ICD-10, the boundaries between schizophrenia, schizoaffective disorder, and mood disorder were not clearly differentiated. This could result in patients with schizophrenia and mood disorder receiving an inappropriate diagnosis of schizoaffective disorder.[7],[8]

Other problems with the ICD-10 diagnostic guidelines included the significance given to Schneider's first-rank symptoms particularly bizarre delusions.[9],[10] The construct also did not appear to closely connect with findings in relation to neurobiological markers[4] and genetics[3],[11] or with specific pharmacological treatments.[12]

 Psychosis and Related Disorders in International Classification of Disease-11



Following is a summary of the major diagnostic categories in psychosis and related disorders in proposed ICD-11 draft and how these differ from ICD-10. The structure proposed for ICD-11 block on “Schizophrenia spectrum and other primary psychotic disorders” includes the following categories:

SchizophreniaSchizoaffective disorderAcute and transient psychotic disorders (ATPD)Schizotypal disorderDelusional disorderOther primary psychotic disorders.

The section “F2 schizophrenia, schizotypal, and delusional disorders” has been renamed as “schizophrenia spectrum and other primary psychotic disorders.” The term “primary” is used to distinguish these disorders from “secondary” psychotic disorders such as psychotic disorders secondary to substance use and withdrawal, which will be placed in the mental and behavioral disorders associated with disorders or diseases classified elsewhere.[12]

Schizophrenia

ICD-11 includes the option of providing a specification of the level of severity for six symptom domains for the disorders included in schizophrenia and other primary psychotic disorders (with the exception of schizotypal disorder).[13] These domains (positive symptoms, negative symptoms, depressive mood symptoms, manic mood symptoms, psychomotor symptoms, and cognitive symptoms) can be rated as not present, mild, moderate, or severe.[14] The nine ICD-10 subtypes will be omitted[15] as these were not stable and of questionable prognostic validity.[16]

Positive – includes delusions, hallucinations, experiences of passivity and control, disorganized behavior, and thinkingNegative – covers a reduction or restriction in affect, speech, motivation, and social interactionsDepressive/Manic – covers mood symptoms which do not meet the full requirement for a diagnosis of schizoaffective disorder. These dimensions reflect mood symptoms rather than mood syndromes (e.g., symptoms related to disruption of appetite and sleep)Psychomotor symptoms – encompass a wide range of motor disturbances including increased activity in the form of purposeless behaviors such as fidgeting, stereotypy, wringing of hands and inability to sit; generalized slowing of speech and/or movements; and catatonia symptomsCognitive impairment – includes deficits in processing speed, attention/concentration, orientation, judgment, and working memory. This would be best assessed through locally validated neuropsychological testing.

In ICD-11, course qualifiers have been changed to distinguish between first episode, multiple episodes, full or partial remission as well as continuous cases. All will be rated on a binary rating scale (0 – absent, 1 – prominent).[17] In DSM-5, symptoms may be rated for their current severity (most severe in the last 7 days) on a 5-point scale ranging from 0 (not present) to 4 (present and severe).

There is significantly less emphasis on the importance of first-rank symptoms in diagnosing schizophrenia due to the lack of evidence for the specificity of these symptoms for schizophrenia and their debatable prognostic significance.[10],[18],[19] The diagnosis of schizophrenia will require the presence of at least two out of seven symptoms including at least one core symptom. Core symptoms include persistent delusion of any kind; distortion of self-experience, for example, thought interference/thought withdrawal, passivity phenomena; persistent hallucination in any modality; and thought disorder.[17]

Patients presenting with symptoms which do not fulfill the symptom or the duration requirement of any specific psychotic disorder will be classified among the “other primary psychotic disorders.”[12],[17] The 1-month duration criterion is retained based on the high stability of the ICD-10 diagnosis[16],[17] and the lack of evidence suggesting a different duration criterion.[20]

Schizoaffective disorder

A diagnosis of schizoaffective disorder would only be made in ICD-11 when the definitional requirement of schizophrenia is met concurrently with mood symptoms that meet the definitional requirements of a moderate or severe depressive episode, a manic episode, or a mixed episode. This requirement is more restrictive compared to ICD-10, which just required the presence of symptoms of schizophrenia and mood disorder. The total duration requirement would be 4 weeks.[14]

A cross-sectional approach was maintained in the ICD-11 for schizoaffective disorders as there is no evidence on how a longitudinal “lifetime” criterion impacts cross-sectional inter-rater reliability, and the reliability of lifetime symptoms' report by patients and retrospective assessment by clinicians remains unknown.[21]

Acute and transient psychotic disorders

ATPD has not received much research attention although the concept has been around for >2 decades. A recent review found that the ICD-10 ATPD diagnosis has a stability of 63%–100% over a 1–3 year period.[22] Shorter duration of illness (<1 month) and abrupt onset (<48 h) tend to predict a stable diagnosis of ATPD and most patients tend to recover fully in 2–3 months.[22]

For the ATPD, the diagnostic focus would be on its sudden onset, brief duration, volatility/fluctuation of psychotic and affective symptoms.[17],[23] Due to the lack of support for prognostic and therapeutic relevance of the distinctions made in ICD-10 among the several subtypes of ATPD, the working group for psychotic disorders retained the description of the subcategory F23 (acute polymorphic psychotic disorder without symptoms of schizophrenia) as the diagnostic guideline for ATPD. The delusional subtype (F23.3) was incorporated into the revised “delusional disorder” category.[12],[17] The ICD-10 F23.1 (acute polymorphic psychotic disorders with symptoms of schizophrenia) and F23.2 (acute schizophrenia like psychotic disorder) were collapsed into “other primary psychotic disorders” if the duration of disorders is less than 4 weeks. If duration exceeds 4 weeks, then schizophrenia should be diagnosed.

ICD-11 ATPD differs from “brief psychotic disorder” in DSM-5, which uses 4 of the 5 symptoms of schizophrenia but does not require the presence of a polymorphic fluctuant picture. Moreover, ICD-11 and ICD-10 ATPD allow symptom duration of 3 months (as against 1 month in DSM-5) in view of the modal duration of remitting acute psychosis with acute onset being 2–4 months.[24]

Delusional disorder

F22 “persistent delusional disorder,” F24 “induced delusional disorder,” and F23.3 “other acute predominantly delusional disorder” have been collapsed into a single diagnostic category “delusional disorder” to simplify the classification system.[12],[17]

 International Classification of Disease-11 and Diagnostic and Statistical Manual-5



[Table 1] details the comparison of the classification of psychosis in ICD-11 and DSM-5. The two systems correspond better to each other than their earlier versions. In both systems, now, there is less emphasis on first-rank symptoms. The replacement of subtypes of schizophrenia with symptom qualifiers has also brought the two systems closer. Both systems now propose the inclusion of cognitive impairments in the diagnostic fold, and course qualifiers have been aligned. Neither DSM-5 nor ICD-11 has included the “attenuated psychosis syndrome” characterized by psychosis-like symptoms below a threshold for full psychosis[25] as a diagnosable entity. The DSM-5 has included this syndrome in its appendix as a clinical condition which requires more research.{Table 1}

Some major differences remain between DSM-5 and ICD-11 in the classification of psychosis (e.g., the course qualifiers). The 1-month duration criterion was retained in ICD-11 due to the high stability of the ICD-10 diagnosis over time[16] and lack of evidence supporting alternate duration criteria.[20] The ICD-11 working group also felt that the benefit of early treatment due to the lower duration requirement would outweigh concerns regarding labeling individuals with a diagnosis. In addition, ICD-11 includes distortions of self-experience (passivity phenomenon and thought insertion/withdrawal) as symptoms that could count for the diagnosis of schizophrenia; however, in DSM-5, only hallucinations or delusions (related or unrelated to these phenomena) have been included in diagnostic criteria.

Characterizing patients with both mood and psychotic symptoms has been a longstanding nosological challenge. This has been reflected in the poor reliability and low diagnostic stability and questionable validity of schizoaffective disorder in DSM-IV.[26] Unlike the cross-sectional diagnosis in ICD-11, DSM-5 has specified longitudinal requirements for schizoaffective episodes and stated that schizoaffective disorder can be lifetime diagnosis. It also requires that a “major mood episode” should be present for “a majority of the total duration of the illness” in order to make a diagnosis of schizoaffective disorder to provide a clearer separation between schizophrenia with mood symptoms and schizoaffective disorder.

Another difference between the two systems is the requirement of functional impairment in DSM-5 for the diagnosis of mental disorders. ICD-11 does not propose functional impairment as a mandatory requirement.

 The Clinical Utility of the New Classification System



While most classification systems are naturally concerned with reliability and validity of diagnostic categories, there is increasing concern that current diagnostic systems have major problems regarding clinical utility;[27] in terms of high use of “unspecified/not otherwise specified” diagnoses, presence of high comorbidity, and limited correspondence between diagnoses and specific treatments – both psychological and pharmacological.

One of the contributors to poor clinical utility is its extraordinary complexity of current diagnostic systems, with each revision including more categories, more subtypes, and more qualifiers focused on increasingly fine distinctions. These distinctions have minimal validity but are difficult to use in clinical practice. Although the clinical utility of the present guidelines will be tested in practice in the future, we feel that some changes such as removing the subtypes of schizophrenia or simplifying the diagnosis of ATPD will enhance their clinical utility. The suggestion to subtype schizophrenia based on treatment response by Farooq et al.[28] has the potential to further enhance the clinical utility of classification for schizophrenia; however, classificatory systems are not yet ready for such as paradigm shift.

The classification of ATPD is particularly relevant in developing countries contexts and a good example of how an overly complex classification can lose clinical relevance. A number of studies mainly emanating from India have shown that ATPD is significantly more common in developing than in industrialized countries settings.[29] However, in clinical practice, the diagnostic category as specified in ICD-10 is much less commonly used, perhaps due to complexity of clinical descriptions and need for differentiation between four subtypes. This may also partly be responsible for the current state of poor evidence base for the treatment of ATPD. A recent systematic review documented the presence of four trials that have evaluated the effectiveness of pharmacological interventions for ATPD with total sample size of just over 100 patients across the trials.[30]

We believe that the future revisions of the classifications must be informed by the validity and reliability of a construct as well as the clinical utility. This requires that clinicians are involved alongside academicians and epidemiologists in any revision of the classifications. This is particularly important for psychosis, as the diagnostic label can have life-changing consequences for the persons receiving such diagnosis. The epidemiology of psychosis in developing countries also needs to be considered in future classification revisions.

The current classification of psychosis and related disorders represents a major improvement. However, in the absence of clear biological markers, the classification at best represents the consensus reached among the experts in the field. The defining features of disorders are still based on the epidemiological and phenomenological data. It is hoped that future research in genetics and neuroimaging may provide robust basis of the classification of psychosis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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