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A qualifier for each coded diagnosis to indicate the onset of the condition relative to the beginning of 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 " Condition onset flag code N ".
Data Type Number
Format N
Maximum character length 1
Value Meaning Start Date End Date
Permissible Values 1 Condition with onset during the episode of admitted patient care
2 Condition not noted as arising during the episode of admitted patient care
Supplementary Values 9 Not reported


Guide for use:

Assign the relevant condition onset flag to ICD-10-AM diagnosis codes assigned in the principal diagnosis and additional diagnosis fields for the National Hospital Morbidity Database collection.

The sequencing of diagnosis codes must comply with the Australian Coding Standards and therefore diagnosis codes should not be re-sequenced in an attempt to list diagnosis codes with the same condition onset flag together.

When it is difficult to decide if a condition was present at the beginning of the episode of care or if it arose during the episode, assign a value of 2 - Condition not noted as arising during this episode of care.

The principal diagnosis should always have a condition onset flag value of 2.

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

When a single diagnosis code describes a condition and that code contains more than one concept (e.g. diabetes with renal complications) and each concept within that code has a different condition onset flag, then assign a value of 2.

When a condition requires more than one diagnosis code to describe it, it is possible for each diagnosis code to have a different condition onset flag.

The flag on Z codes related to the outcome of delivery on the mother’s record (Z37), should always be assigned a value of 2.

The flag on Z codes related to the outcome of delivery on the baby’s record (Z38), should always be assigned a value of 2.

Australian Institute of Health and Welfare


The condition onset flag is a means of differentiating those conditions which arise during, or arose before, an admitted patient episode of care. Having this information will provide an insight into the kinds of conditions patients already have when entering hospital and what arises during the episode of care. A better understanding of those conditions arising during the episode of care may inform prevention strategies particularly in relation to complications of medical care.

The flag only indicates when the condition had onset, and cannot be used to indicate whether a condition was considered to be preventable.


Related content

Relation Count
Inclusion in Data Set Specifications 6
Inclusion in Data Distributions 0
As a numerator in an Indicator 15
As a denominator in an Indicator 5
As a disaggregation in an Indicator 9