What is ICD-11 code 6A05.2, the WHO classification for combined presentation ADHD?

6A05.2 is the ICD-11 code for ADHD with both inattention and hyperactivity-impulsivity

The International Classification of Diseases, 11th Revision, is the World Health Organization's global system for naming and coding health conditions. In ICD-11, attention deficit hyperactivity disorder has the parent code 6A05, within the chapter on neurodevelopmental disorders. The digit after the point identifies the presentation:

• 6A05.0 Attention deficit hyperactivity disorder, predominantly inattentive presentation.
• 6A05.1 Attention deficit hyperactivity disorder, predominantly hyperactive-impulsive presentation.
• 6A05.2 Attention deficit hyperactivity disorder, combined presentation.
• 6A05.Y Attention deficit hyperactivity disorder, other specified presentation.
• 6A05.Z Attention deficit hyperactivity disorder, presentation unspecified.

So 6A05.2 is not a separate condition. It is the standard ADHD diagnosis with a specifier saying that both symptom groups are clearly present. The code describes the shape of the symptoms, not how severe they are or how much they interfere with life. The letters Y and Z in the last two codes are ICD-11 conventions used across the whole classification: Y for other specified, when a clinician wants to record a presentation that does not fit the named ones, and Z for unspecified, when the presentation has not been determined or recorded.

Combined presentation means both symptom groups are clinically significant at the same time

ICD-11 describes ADHD as a persistent pattern of inattention and/or hyperactivity-impulsivity that begins during the developmental period, typically early to mid-childhood, is outside the limits of normal variation for the person's age and development, and has a direct negative impact on academic, occupational or social functioning. The inattention features include difficulty sustaining attention, distractibility, disorganisation and forgetfulness. The hyperactivity-impulsivity features include excessive motor activity, restlessness, difficulty waiting, and acting without considering consequences.

Combined presentation is assigned when both sets of features are clinically significant. Predominantly inattentive presentation is used when inattention dominates and hyperactivity-impulsivity is mild or absent, and the reverse for predominantly hyperactive-impulsive presentation. In adults, inattentive and combined presentations are the most common, because overt hyperactivity tends to lessen with age while inner restlessness and impulsivity often continue. An adult coded 6A05.2 typically describes both sides: losing track of tasks and conversations, and also fidgeting, talking over people, making quick decisions they later regret, or feeling driven by a motor that will not switch off.

ICD-11 brought the WHO classification into line with the DSM presentations

The previous revision, ICD-10, did not use the term ADHD at all. It classified hyperkinetic disorders under F90, and the main code, F90.0, required inattention, hyperactivity and impulsivity all to be present. People with predominantly inattentive symptoms fit poorly. ICD-11 adopted the ADHD name and the three presentations, which closely mirror the DSM-5-TR.

The two modern systems are not identical. DSM-5-TR sets fixed symptom counts, at least six in a group for children and at least five from age 17, while ICD-11 describes the essential features without a numerical threshold. The practical differences are covered in how ICD-11 and DSM-5-TR differ in how they define ADHD.

In Canada the diagnosis is made with DSM-5-TR and the ICD code appears on paperwork

Canadian clinicians, following the CADDRA practice guidelines, assess and diagnose ADHD using the DSM-5-TR criteria. ICD codes come in afterwards, when the diagnosis needs to be recorded in a structured way: on hospital and clinic records, on some insurance and disability forms, and in health statistics. Canadian hospitals still largely code with ICD-10-CA, the Canadian adaptation maintained by the Canadian Institute for Health Information, so you may see an F90 code on one document and a 6A05 code on another. Neither code changes the diagnosis; they are two coding systems describing the same clinical finding at different points in the health system.

The presentation code reflects your current symptoms, and it can change. DSM-5-TR explicitly allows the presentation specifier to be updated over time, so someone coded as combined presentation in childhood may be described as predominantly inattentive as an adult. A change in code is a description of how symptoms look now, not a new diagnosis and not a downgrade.

If 6A05.2 appears on your own documents, it simply names your presentation

Seeing a code can feel clinical and a little opaque. It carries less information than the surrounding report: it does not state severity, which DSM-5-TR rates separately as mild, moderate or severe, and it says nothing about which treatment is appropriate. If the code on a form does not match what you understood about your diagnosis, ask the clinician who wrote it; a mismatch between combined and inattentive presentation is usually a judgement call about how prominent the hyperactive-impulsive features are, and it can be revised at a follow-up if your symptoms are better described another way.

At Finding Focus, online ADHD assessment and treatment is available to adults and teens in several Canadian provinces, with a short online intake followed by a consultation with a licensed Canadian clinician, no referral needed, from $399. Documentation states the DSM-5-TR diagnosis and presentation in plain language, and our page on what is included in an ADHD diagnosis letter explains what institutions typically expect to see.