Combining diagnoses: causes, manifestations and clusters

When one condition causes another

Some conditions are linked. One causes the other, or shows itself through the other. How does ICD-11 record that?

Cause, manifestation, association

ICD-11 gives three ways to link conditions. Has causing condition: the causing condition must be coded when it is known. WHO compares it to the dagger code in ICD-10. Has manifestation: coding a manifestation is optional, and WHO compares it to the asterisk code. And associated with: conditions captured together, without implying cause and effect.

• Has causing condition · Cause · Must be coded when known. WHO compares it to the ICD-10 dagger code.
• Has manifestation · Effect · Optional. WHO compares it to the ICD-10 asterisk code.
• Associated with · Together · Conditions captured together without implying cause and effect.

Diabetic retinopathy due to diabetes

A patient is admitted for laser treatment of diabetic retinopathy due to type 2 diabetes. The retinopathy meets the definition of main condition, so it comes first. The causing condition, type 2 diabetes, follows, joined with a slash.

• Main condition · 9B71.0Z · Diabetic retinopathy, unspecified. It meets the definition of main condition.
• Causing condition · 5A11 · Type 2 diabetes mellitus, linked to it.

The order follows the use case

When two stem codes are linked, the order follows the use case. A patient died of diabetic coma with type 2 diabetes. For mortality, the underlying cause comes first. A patient is admitted in diabetic coma. For morbidity, the main condition comes first. Same two conditions, different order.

Each stem keeps its own extensions

Clusters can hold more than one stem code, each with its own extensions. Left inguinal hernia with acute obstruction. The first stem code and its extension, joined with an ampersand. A slash. Then the second stem code and its extension, again with an ampersand.

• First stem and its extension · DD51&XK8G · Inguinal hernia, left.
• Second stem and its extension · ME24.2&XT5R · Digestive system obstruction, acute.

Only when the link is documented

There is a limit. Where an established causal relationship is not documented, or cannot be inferred, the two stem codes cannot be part of the same cluster. Ambiguous connecting words such as with, after, in or following do not establish one either. A patient admitted for right cataract extraction who also has type 2 diabetes: the cataract is the main condition, the diabetes is another condition, and they are coded separately.

• Linked · 9B71.0Z/5A11 · The causal relationship is documented, so the codes can form one cluster.
• Not linked · 9B10&XK9K · A right cataract and type 2 diabetes with no documented causal link: separate codes.
• Ambiguous words · with, after · Words such as with, after, in and following do not establish a cause: code each condition separately.

Check yourself

Pause and think. A right cataract and type 2 diabetes mellitus are both documented, with no documented causal link. How should they be coded? The answer: Separately: the cataract with its laterality, and the diabetes as another condition. Where a causal relationship is not documented or cannot be inferred, the two stem codes cannot be part of the same cluster.

• One cluster linking the cataract to the diabetes
• Separately: the cataract with its laterality, and the diabetes as another condition
• Only the diabetes
• Only the cataract

Keep these in mind

Code the causing condition when it is known. Manifestations are optional and linked to their cause. A slash between stem codes, an ampersand for extensions. And cluster only what is documented as linked.

• Causing condition: code it when known
• Manifestation: optional, linked to its cause
• Slash between stem codes, ampersand for extensions
• Cluster only what is documented as linked