DSM-5 versus ICD-10: Diagnostic Codes for Mental Health

CPT, ICD-10, DSM-5, oh my! With so many different types of code sets, how do you know which to use when? The ICD-10 and DSM-5 are particularly confusing since they each include mental health diagnostic codes, and in the newest version of the DSM, the codes overlap significantly. In this post, we’ll look at exactly what ICD-10 codes and DSM-5 codes are and what you need to know when using them. We’ll also explore how the ICD-10 is organized so it’s easier to find your way around the code set.

What are ICD-10 Codes?

The International Classification of Disease (ICD) is a classification tool for medical diagnoses compiled and updated by the World Health Organization (WHO). The current version is the ICD-10. The U.S. has developed a clinical modification (ICD-10-CM) based on the WHO’s ICD-10 set. The U.S. version has over 70,000 different codes that are used in the healthcare claims submission process for purposes of reporting and reimbursement. The codes describe diseases, signs and symptoms, abnormal findings, complaints, and external causes of injury or diseases. An ICD-10 code tells a client’s insurance company why you provided the client with the services you did, helping to justify the services.

How the ICD-10 is Organized

ICD-10 codes are organized into a specific system, which makes it easier to find the code you’re looking for. Having a general understanding of how the codes are organized will serve you well.

All ICD-10 codes start with a single letter, followed by three or more numbers. The first three characters identify the category of the diagnosis and additional characters provide more detail for the diagnosis, such as the severity or location of the issue in the body. 

The codes that are applicable to mental health fall under three main categories. The G codes all describe diseases of the nervous system. The Z codes refer to situations where the client doesn’t have a specific disorder but services are required, such as codes Z91.4 (personal history of psychological trauma) and Z04.6 (encounter for general psychiatric examination, requested by authority). 

The F codes make up the majority of the mental health ICD-10 codes, which are divided into the following categories.

  • F00–F09 — organic, including symptomatic, mental disorders
  • F10–F19 — mental and behavioral disorders due to psychoactive substance abuse
  • F20–F29 — schizophrenia, schizotypal, and delusional disorders
  • F30–F39 — mood disorders, depression, and bipolar disorders
  • F40–F49 — neurotic, anxiety, stress-related, and somatoform disorders
  • F50–F59 — behavioral syndromes associated with physiological disturbances and physical factors
  • F60–F69 — disorders of adult personality and behaviors
  • F70–F79 — intellectual disabilities
  • F80–F89 — pervasive and specific developmental disorders
  • F90–F98 — behavioral and emotional disorders with onset usually occurring in childhood and adolescence
  • F99 — unspecified mental disorder

What are DMS-5 Codes?

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is well-known to mental health therapists and has its own set of codes. Healthcare professionals refer to this handbook, published by the American Psychological Association (APA) as the authoritative guide to the diagnosis of mental disorders as it provides a comprehensive list of diagnostic criteria for each recognized mental disorder. The current version is DSM-5. This version of the DSM made a significant effort to align with the ICD-10 codes, but because DSM-5 and ICD-10 aren't strictly related, there are still occasional disconnects between the diagnoses in the two sets. 

The DSM-5 provides a more comprehensive look at mental illness and will always be the primary resource for diagnosing a client, but you’ll need to double-check the ICD-10 to make sure that the code recommended by the DSM-5 accurately fits the specifics of your diagnosis. Insurance companies require ICD-10 diagnostic codes, and they won’t reimburse for services if you don’t use them. 

Why Are There Still Two Sets of Codes?

The initial reason that the WHO and the APA developed their own sets of codes is that the two manuals served very different purposes in the beginning. The DSM was designed to help mental health professionals identify very specific disorders so that they could best communicate with other professionals and understand how to treat their patients most effectively. The ICD was designed to provide a comprehensive reference point for classifying diseases and sharing knowledge amongst professionals worldwide, particularly in the cases of epidemics and pandemics. Insurers picked up the use of the ICD as a simple way to reference diagnoses. 

Over time, as the WHO has become more interested in the nuances of different diseases and because of the way the code set is now used, the ICD codes have become much more specific. This has resulted in the two sets of codes looking more and more alike. And as we mentioned, the newest version of the DSM has actually sought to align its codes with the ICD-10. 

In the future, it’s entirely likely that the ICD will continue to make its codes more detailed and specific, accounting for each individual disorder. At some point, it’s possible that the DSM codes may be eliminated and replaced with the ICD codes. But for now, therapists will need to use the DSM to diagnose and the ICD to identify the correct code associated with the diagnosis for billing purposes. 

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