Record each additional diagnosis relevant to the episode of care in accordance with the International statistical classification of diseases and related health problems, 10th revision, Australian modification (ICD-10-AM) Australian Coding Standards. Generally, external cause, place of occurrence and activity codes will be included in the string of additional diagnosis codes. In some data collections these codes may also be copied into specific fields.

The diagnosis can include a disease, condition, injury, poisoning, sign, symptom, abnormal finding, complaint, or other factor influencing health status.

Additional diagnoses give information on the conditions that are significant in terms of treatment required, investigations needed and resources used during the episode of care. They are used for casemix analyses relating to severity of illness and for correct classification of patients into Australian Refined Diagnosis Related Groups (AR-DRGs).

An additional diagnosis should be recorded and coded where appropriate upon separation of an episode of admitted patient care or the end of an episode of residential care or attendance at a health-care establishment. The additional diagnosis is derived from and must be substantiated by clinical documentation.

Additional diagnoses should be interpreted as conditions that affect patient management in terms of requiring any of the following:

• commencement, alteration or adjustment of therapeutic treatment
• diagnostic procedures
• increased clinical care and/or monitoring

In accordance with the Australian Coding Standards, certain conditions that do not meet the above criteria may also be recorded as additional diagnoses.

Additional diagnoses are significant for the allocation of AR-DRGs. The allocation of a patient to major problem or complication and co-morbidity Diagnosis Related Groups is made on the basis of the presence of certain specified additional diagnoses. Additional diagnoses should be recorded when relevant to the patient's episode of care and not restricted by the number of fields on the morbidity form or computer screen.

External cause codes, although not diagnosis of condition codes, should be sequenced together with the additional diagnosis codes so that meaning is given to the data for use in injury surveillance and other monitoring activities.

Independent Hospital Pricing Authority

Australian Consortium for Classification Development