Chapter 2 – ICD-11 + DSM-5 = A Diagnostic Babel


The ICD and DSM are both useful systems of psychiatric diagnosis, alike enough to be roughly comparable, but different enough to cause confusion and misuse. Both systems are in wide use around the world and are likely to remain so. Neither system is clearly better than the other – we would be much better off having either one, rather than both.

Let us confuse their language so they will not understand each other.

Genesis 11:7

The ICD and DSM are both useful systems of psychiatric diagnosis, alike enough to be roughly comparable, but different enough to cause confusion and misuse. Both systems are in wide use around the world and are likely to remain so. Neither system is clearly better than the other – we would be much better off having either one, rather than both.

The ICD-11 and DSM-5 also share the same major flaws. Both provide very loose definitions of ‘mental disorder’ that encourage the overdiagnosis of people with minor problems and the neglect of those with severe ones. Both are based mostly on the consensus of experts who were strongly biased towards adding new diagnoses. Neither required the presence of compelling scientific evidence to support adding new diagnoses or making changes in existing ones.

One of my main goals for DSM-IV 30 years ago was to reduce disparities between it and ICD-10 (which was prepared at the same time). We convened numerous meetings, bringing together teams of experts working on both systems, hoping to forge mutually acceptable compromise definitions for as many disorders as possible. Sometimes we succeeded, but mostly we failed. Local preferences, professional rivalries, and national loyalties tended to trump ecumenical cooperation. The separate groups that later created DSM-5 and ICD-11 have unfortunately widened the gulf even further between the two systems.

I will discuss eleven of the new disorders that were newly added to ICD-11. Some of these had already been introduced by DSM-IV (Bipolar II) or DSM-5 (Catatonia; Binge Eating; Premenstrual Dysphoric; Hoarding); some were given official recognition for the first time in ICD-11 (Complex PTSD; Prolonged Grief; Gaming; Compulsive Sexual Behaviour; Body Integrity Dysphoria; and a radically new system of diagnosing Personality Disorder).

Why so many new diagnoses in ICD-11? Unfortunately, it failed to learn from DSM-5’s mistakes and made no effort to contain the ever-exploding inflation in psychiatric diagnosis. Both systems gave their expert consultants far too much control over final decision making. Experts in each area of psychiatric diagnosis are necessary contributors to the process of revising the diagnostic system – but they should never be allowed final decision-making power over their own area of particular interest. Experts always love their research pets, hype their benefits, ignore their risks. They worry greatly about missed patients, while blithely ignoring the risks of mislabelling normals. New diagnoses that work for experts in hothouse research environments are often a disaster in real-world psychiatric and primary care practice. I have never known any experts, among the many hundreds I’ve worked with, to ever suggest narrowing the definitions in their area of expertise. Their bias is always to accept new diagnoses and loosen definitional thresholds for existing ones.

Adding new diagnoses almost always turns out to be a bad idea – achieving smaller than expected benefits and risking harmful unrecognized and unintended consequences. Most seemingly promising contenders wind up causing far more problems than they solve. We were very cautious about adding new diagnoses in DSM-IV and accepted only two from among the ninety-four suggested. Both (Bipolar II and Asperger’s) had compelling rationales; extensive literatures; thorough field testing; universal consent. Nonetheless, both triggered unexpected fads of excessive diagnosis and both probably did much more harm than good by virtue of their unanticipated, harmful, unintended consequences. The DSM-5 and ICD-11 have been remarkably welcoming of new diagnoses; they required little empirical support; did little field testing; and fearlessly and carelessly expanded already existing diagnostic inflation.

Overdiagnosis is also encouraged by another new feature of ICD-11. Although it contains criteria sets that look like those in DSM-5, ICD-11 does not offer thresholds for the number of symptoms required before making a diagnosis. Clinicians are instead permitted to use their own clinical judgement when deciding how closely any given patient meets the prototype provided for a given disorder. This makes ICD-11 much easier to use by busy practitioners, but also inherently unreliable and essentially useless for research. It also means that patients on the fuzzy boundary between normal and disorder are more likely to be diagnosed as disordered rather than regarded as subclinical.

By virtue of its many new diagnoses and its abolition of required symptom thresholds, ICD-11 has become the most overinclusive of all the diagnostic systems ever produced in the history of psychiatry. Any future increases in the reported rates of psychiatric disorder should be attributed to the changes ICD-11 has made in the diagnostic system – not to human nature suddenly getting sicker. Tens (or perhaps hundreds) of millions of people around the world who would have been considered normal using previous diagnostic systems will now qualify for an ICD-11 diagnosis.

Disorders Rejected by DSM-5 but Included in ICD-11

The DSM-5 Task Force displayed a strong and consistent bias towards introducing new disorders – consistently exaggerating potential benefits while neglecting very real risks. Published 6 years later, ICD-11 might have learned from DSM-5’s overinclusiveness – but did not. Instead of avoiding further diagnostic inflation, ICD-11 was reckless enough to accept as official categories a large number of new disorders so clearly unworthy they had been roundly rejected by DSM-5. (Editor’s note: in Chapter 1, Geoffrey Reed states that more disorders were removed in ICD-11 than added.)

‘Prolonged Grief Disorder’

There can never be a uniform expiration date on normal grief – and ICD-11 should not have felt empowered to impose one. People grieve in their own ways, for periods of time that vary widely depending on the person; the nature of the loss; and relevant cultural practices. Mislabelling grief as mental disorder stigmatizes the grievers; exposes them to unneeded psychiatric medication; and insults the dignity of their loss. The decision to declare ‘Prolonged Grief’ a psychiatric disorder was based on minimal research by just a few research teams; has not been field tested in a wide array of practice settings to smoke out harmful unintended consequences; and, perhaps most importantly, creates many new problems while serving no useful purpose. If a diagnosis is needed for prolonged grievers suffering ‘clinically significant distress or impairment’, ‘Major Depressive Disorder’ or ‘Adjustment Disorder’ have always been available and should be used now. I strongly encourage clinicians to use common sense and clinical judgement. Don’t follow any ICD-11-induced fad to suddenly pathologize what is one of humanity’s most ubiquitous, basic, and essential life experiences.

‘Complex PTSD’

The ICD-11 provides a very narrow definition for its new diagnosis ‘Complex PTSD’. The patient must meet all criteria for PTSD and in addition have ‘persistent, pervasive, and enduring disturbances in affect regulation, self-concept, and relational functioning’. These symptoms were previously covered in DSM-5 and ICD-10 as associated features of PTSD. I see no great gain in creating this entirely new PTSD diagnosis just to describe its most severe and persistent form. And there is one potential great harm – ICD-11’s narrow ‘Complex PTSD’ may be confused with a much broader and much riskier conception of ‘Complex PTSD’ that was rightfully rejected by both DSM-IV and DSM-5. The label ‘Complex PTSD’, as it was proposed for DSM and as it is commonly used in the literature, dramatically loosens the ‘PTSD’ definition by including many of the most common problems adults present with and attributing them to a wide array of often poorly defined and hard to determine childhood traumas. The DSM proposals were wildly overinclusive and impossibly unreliable, and made the bold claim that much of adult psychopathology is caused by childhood trauma. Symptoms were non-specific, far ranging, and overlapping with many other disorders, including shame, guilt, anxiety, difficulty in controlling emotions, impulsivity, dissociation, persistent physical symptoms, interpersonal problems, self-destructive and suicidal behaviours, substance abuse, and personality problems. To avoid possible confusion between the narrow ICD-11 definition and common usage, I suggest clinicians avoid the diagnosis ‘Complex PTSD’ and instead use ‘PTSD, severe’.

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Oct 25, 2023 | Posted by in NEUROLOGY | Comments Off on Chapter 2 – ICD-11 + DSM-5 = A Diagnostic Babel

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