Top 10 Things You May Not Know About the ICD-10

American clinicians are often unfamiliar with ICD-10. Here's some basic info.

Posted Dec 13, 2017

#10: It is only new to the United States.

ICD is the acronym for the International Classification of Diseases, which is the diagnostic manual of the World Health Organization (WHO). The ICD includes all officially recognized illnesses and medical conditions—including a section on mental and behavioral disorders that is important for mental health professionals. The current version is the ICD-10, which was published back in the early 1990s. As a member of the World Health Organization, the United States is required to use the ICD. However, even though ICD-10 came out more than two decades ago and has been in use in other WHO-member countries for a long time, the U.S. only switched from ICD-9 to ICD-10 in 2015.

#9: It is available for free online.

Unlike the DSM-5, both the original version and the U.S. modification of the ICD-10 (known as ICD-10-CM, with "CM" standing for "clinical modification") are available for free online. Thus, when American clinicians lament that they must buy the DSM in order to practice, that is simply not so. The ICD-10 can be used instead at no cost. In fact, the mental and behavioral disorders section of the manual is accessible on the web as a free PDF.

#8: It is the keeper of the (diagnostic) codes.

Many American clinicians don't actually know where the diagnostic codes associated with each mental disorder come from (no, not the stork). Why are they confused about this? Because most clinicians pull the codes from the DSM-5. Thus, they understandably assume that these codes originate in the DSM-5—but they don't. In fact, all diagnostic codes for mental disorders come from the ICD. The DSM-5 simply appropriates these codes. Thus, not only is the ICD-10 available for free online, but so are all the diagnostic codes American psychotherapists need for insurance billing.

WHO website
Source: WHO website

#7: It adheres to a medical model.

Like the DSM-5, the ICD-10 adheres to a medical model—meaning that it organizes symptoms that tend to co-occur into categories and then treats these categories as disorders people "have." That is, even if it doesn't take a formal position on how best to remedy the disorders it contains, the ICD-10 views presenting problems as dysfunctions inside of people that are most efficiently grouped into distinguishable disease entities. This sort of medical model has dominated practice for a long time and is typically taken for granted, though it certainly is not the only way of conceptualizing human distress.

#6: It uses guidelines, not criteria.

The DSM-5 famously provides diagnostic criteria (strict rules used to determine which behaviors qualify clients for different diagnoses). Such criteria often provide nonnegotiable numbers of symptoms required for a diagnosis, or set durations symptoms must be present for a diagnosis to be made. By contrast, the ICD-10 uses diagnostic guidelines, which are slightly less strict and allow more room for clinician judgment. Those who favor DSM's stricter criteria approach say ICD guidelines leave too much room for clinician judgment, thereby decreasing diagnostic reliability. However, those who prefer ICD guidelines say that rigid DSM criteria don't always allow clinicians to respond to the clients in front of them and make appropriate diagnoses.

#5: Sometimes it is harmonized with the DSM-5; other times it is discordant.

The ICD and DSM try to "harmonize" with one another. That is, each manual tries to make its disorder categories as consistent as possible with the other. Thus, for a large number of diagnoses, the manuals are quite similar. However, occasionally the manuals diverge and are discordant with one another. For instance, the DSM-5 includes ADHD, while the ICD-10's closest equivalent is something called "hyperkinetic conduct disorder." Some of the personality disorder categories don't quite match up, either. See #3 for the specific case of disruptive mood dysregulation disorder.

#4: It has Asperger's disorder in it.

Perhaps the most well-publicized difference between DSM-5 and ICD-10 is that the former no longer includes Asperger's disorder, but the latter does. This has created a fascinating (and confusing) irony that I have discussed elsewhere—namely that until 2013 American clinicians thought they were diagnosing Asperger’s disorder because it was in DSM-IV. However, they actually weren't because all DSM-IV codes came from the ICD-9, which didn't include Asperger's disorder. Thus, the DSM-IV code for Asperger's was technically an "unspecified autism" code. Yet since 2015, when the U.S. adopted ICD-10, there has been an official autism code clinicians can use when diagnosing clients. Why? Because ICD-10 has Asperger's in it. So, even though DSM-5 doesn't include Asperger's, the ICD-10 does—therefore the code for it can be plucked from ICD-10. The irony is that all those years when American clinicians thought they were diagnosing Asperger's, code-wise they were technically diagnosing autism. Now that American clinicians think they cannot diagnose Asperger's because it is no longer in DSM, they actually can because it is in the ICD-10 that the U.S. began using in 2015. Wild!

#3: It doesn't include specific codes for controversial new DSM-5 disorders like disruptive mood dysregulation disorder.

The DSM-5 includes "disruptive mood dysregulation disorder" (diagnosed in children whose behavior is aggressive, angry, or consistently irritable), but the ICD-10 contains no such diagnosis. Therefore, when clinicians think they are diagnosing disruptive mood dysregulation disorder, they technically are diagnosing "mood disorder, other specified" because that is what the code DSM-5 assigned to DMDD actually corresponds to in the ICD-10.

#2: In the rest of the world, it is going to be replaced by ICD-11 soon.

The ICD-11 is slated to be approved by the World Health Organization in mid-2018. Thus, even though the U.S. only recently switched to ICD-10, the ICD-11 is scheduled to arrive very soon. How long it will take the U.S. to adopt ICD-11 remains unclear.

#1: Shifting to it is not especially radical.

Although the DSM-5 is deeply ingrained in most American's minds as the “diagnostic bible” of mental disorders, switching to the ICD-10 is not particularly difficult or radical. Both manuals share the same or roughly comparable diagnoses. Those who have issues with the DSM-5 are unlikely to find a radically different approach in the ICD-10. If you are looking for something more radical, then you probably want to explore the RDoC initiative, the Psychodynamic Diagnostic Manual (PDM-2), or the Hierarchical Taxonomy of Psychopathology (HiTOP). More on those another day!