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A qualifier for each coded diagnosis to indicate the onset and/or significance of the diagnosis to the episode of care, as represented by a code.


Data Element (this item)


This representation is based on the value domain for this data element, more information is available at " Diagnosis onset type code N ".
Data Type Number
Format N
Maximum character length 1
Value Meaning Start Date End Date
Permissible Values 1 Primary condition
2 Post-admit condition
Supplementary Values 9 Unknown or uncertain


Guide for use:

Assign the relevant diagnosis type flag to all of the ICD-10-AM disease codes recorded in the hospital morbidity system. Specific guidelines for correct assignment of diagnosis flag type are in the ICD-10-AM Australian Coding Standards.

The following rules only apply to:

  • diagnoses which meet the criteria in the Australian Coding Standards (ACS) 0001 Principal diagnosis and ACS 0002 Additional diagnoses or a specialty standard which requires the use of an additional code(s).
  • hospital morbidity data.
  • 'episode of care' refers to hospital or day procedure episodes of care.

Explanatory notes:

The flag on external cause, place of occurrence and activity codes should match that of the corresponding injury or disease code.

The flag on morphology codes should match that on the corresponding neoplasm code.

Conditions meeting the criteria of principal diagnosis may, in some cases, have a flag of 2.

National Centre for Classification in Health


Improved analysis of diagnostic information, especially in relation to patient safety and adverse event monitoring.


Related content

Relation Count
Inclusion in Data Set Specifications 1
Inclusion in Data Distributions 0
As a numerator in an Indicator 0
As a denominator in an Indicator 0
As a disaggregation in an Indicator 0