Myth: Partial DID is the same as OSDD

One clinician writes OSDD in the notes. Another talks about partial DID.¹² Then an online discussion treats the words as interchangeable, and suddenly nobody seems to be describing quite the same thing.

Part of the problem is that the manuals don't give clinicians the same set of labels. DSM-5-TR has no partial DID category.² ICD-11 does, alongside DID, other specified dissociative disorder, and unspecified dissociative disorder.¹ This means the manual a clinician uses can change the name available to them.

For quick reference, each code links straight to the relevant WHO ICD-11 entry.¹

ICD-11 diagnosis	Reference code
Dissociative identity disorder	6B64
Partial dissociative identity disorder	6B65
Other specified dissociative disorder	6B6Y
Unspecified dissociative disorder	6B6Z

What does “partial” mean?

In ICD-11, the difference to pay attention to is executive control. With DID, at least two identity states recurrently take control. With partial DID, one dominant state is usually the one handling work, errands, conversations, and most of everyday life. Other states intrude, but they take control infrequently and irregularly. A particularly distressing or emotional situation may be when that happens.³⁴²

The word “partial” causes trouble because it sounds like a severity rating. Here, it describes the pattern of identity states taking control. Someone can meet the partial DID criteria and still have their daily life seriously disrupted.⁴²

Mike Lloyd offers a useful way to picture the disagreement. In his clinical explainer, he places DID and OSDD in separate “buckets.” When he turns to ICD-11, partial DID sits between them.⁵ ICD-11 added a middle category. DSM-5-TR did not.

OSDD covers more than one pattern

A clinician using DSM-5-TR may land on OSDD when dissociative symptoms are causing serious problems but the full criteria for another named disorder do not fit. They also record why.²

One OSDD presentation involves chronic identity disruption without all the features required for DID. That can resemble partial DID, which explains why the labels are often paired online. OSDD also covers other situations, including identity disturbance after prolonged coercive persuasion, short-lived dissociative reactions to stress, and dissociative trance.²

If a record only says OSDD, the name leaves part of the story out.² Which symptoms did the clinician see? What kept the presentation from fitting DID? Their answer matters more than trying to translate OSDD into partial DID by default.

When the diagnosis stays unspecified

Sometimes a clinician has enough information to recognise a dissociative disorder but not enough to choose a more specific diagnosis. ICD-11 uses unspecified dissociative disorder for that situation. The code does not mean partial DID, OSDD-1, or “probably DID.”⁶

If two labels show up, ask which manual each clinician used and what they heard in the person's history. How often does another identity state take control? Where do memory gaps fit? Why did one set of criteria fit better than another? Those answers will tell you more than trying to make OSDD and 6B65 line up word for word.⁷⁸

Footnotes8

Footnotes

1. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Dissociative disorders. Dissociative disorders overview. ICD-11 grouping and structure for dissociative disorder categories. ↩ ↩² ↩³

2. International Society for the Study of Trauma and Dissociation. (2026). Fact Sheet IV – What are the Dissociative Disorders? DID and OSDD clinical definitions. ISSTD overview differentiating DID, OSDD, and related dissociative categories. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

3. World Health Organization. (2024). Clinical descriptions and diagnostic requirements for ICD-11 mental, behavioural and neurodevelopmental disorders. pp. 382-383, Essential (required) features and Additional clinical features. ICD-11 DID requirements, including recurrent executive control by at least two identity states, amnesia, impairment, exclusions, and the normality threshold. ↩

4. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Partial dissociative identity disorder. Code 6B65. ICD-11 code for partial DID, in which one dominant identity state usually handles daily life while non-dominant states intrude and take control infrequently. ↩ ↩²

5. Lloyd, M. (2025). Partial DID or OSDD: Classifying and diagnosing types of dissociation. 03:21, 06:42. Video explanation of DID and OSDD boundaries and partial DID as an intermediate formulation. ↩

6. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Unspecified dissociative disorder. Code 6B6Z. ICD-11 unspecified code used when a specific diagnosis cannot be established. ↩

7. International Society for the Study of Trauma and Dissociation. (2011). Guidelines for treating dissociative identity disorder in adults, third revision. Journal of Trauma & Dissociation, 12(2), 115-187. pp. 128-130. Differential diagnosis and common sources of diagnostic confusion. ↩

8. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Dissociative identity disorder. Code 6B64. ICD-11 coding and diagnostic criteria family for DID. ↩