Classification of Hospital Acquired Diagnoses

The Classification of Hospital Acquired Diagnoses (CHADx) allows hospitals to identify, count and monitor adverse events that occur in hospital to support safety improvement efforts.

CHADx classification

The CHADx (pronounced ‘Chaddix’) classifications are generated using existing data that is routinely generated from the patient medical clinical record through the assignment of codes using the International Classification of Diseases (ICD-10-AM).

The CHADx classification groups over 4,500 ICD-10-AM codes into a hierarchy of 17 classes and 144 sub-classes of adverse events. The adverse events are identified using these diagnosis codes along with the condition onset flag to indicate that the adverse event occurred in hospital.

Hospital Acquired Complications (HACS) list

While the CHADx remains a useful taxonomy of adverse events, the Commission has since developed the Hospital Acquired Complications (HACS) list to provide a shorter, more manageable list of adverse events that can be used to monitor safety.

These HACs were prioritised through a clinician-led process based on preventability, patient impact (severity), health service impact and clinical priority. The CHADx can be used in conjunction with the HACs to explore adverse events in additional detail.

CHADx history

The CHADx was developed by researchers at the Australian Centre for Economic Research on Health at the University of Queensland for the Australian Commission on Safety and Quality in Health Care (the Commission). During 2010–11, the Commission mapped the classification to ICD-10-AM seventh edition, and reviewed and refined the counting rules associated with allocating diagnoses to a CHADx class.

The Commission undertakes regular reviews of the CHADx to maintain reference code sets. In the latest review, undertaken in 2017, the classification was updated by mapping to ICD-10-AM tenth edition.

CHADx categories

The 17 CHADx categories are:

  • CHADx 1     Postprocedural complications
  • CHADx 2     Adverse drug events
  • CHADx 3     Accidental injuries
  • CHADx 4     Specific infections
  • CHADx 5     Cardiovascular complications
  • CHADX 6     Respiratory complications
  • CHADx 7     Gastrointestinal complications
  • CHADx 8     Skin conditions
  • CHADx 9     Genitourinary complications
  • CHADx 10    Hospital-acquired psychiatric states
  • CHADx 11    Early pregnancy complications
  • CHADx 12    Labour, delivery & postpartum complications
  • CHADx 13    Perinatal complications
  • CHADx 14    Haematological disorders
  • CHADx 15    Metabolic disorders
  • CHADx 16    Nervous system complications
  • CHADx 17    Other complications.