Appendix B – Hospitalisations

The data used in this report for hospitalisation are drawn from the Australian Institute of Health and Welfare (AIHW) National Hospital Morbidity Database. This database includes data on virtually all hospital admissions in Australia, in both public and private hospitals. Data are collected for each episode of hospital care (called a hospital separation), which starts when a patient is admitted to hospital and ends when the hospital stay ends, or there is change in the type of care (for example, from acute care to rehabilitation hospital care).

Most diseases or conditions are recorded as a diagnosis following these criteria:

  • Diseases are recorded as principal diagnosis when they are considered to be the primary reason for the patient being hospitalised.
  • Diseases that coexist with principal diagnosis, or arise during the episode of care, are recorded as additional diagnoses when they affect the management of patients in terms of requiring therapeutic treatment, diagnostic procedures, or increased nursing care and/or monitoring (AIHW 2024).

Algorithm for identifying acute rheumatic fever and rheumatic heart disease in hospital data

The algorithm for identifying acute rheumatic fever (ARF) and rheumatic heart disease (RHD) in hospital data is adopted from the ABDS 2015, where the ICD-10-AM code allocations for identifying RHD and nRVD in hospitals data were developed (Katzenellenbogen et al. 2019). Based on this algorithm:

ICD-10-AM codes I05.0, I05.1, I05.2, I06 and I09 are counted under RHD. This includes principal (PDx) and additional (ADx) diagnoses.

However, if the PDx or ADx is I05.8, I05.9, I08.0, I08.1 or I08.3 then:

  • if the person is under 60 years of age, does not have nRVD codes (I34–I39) and no congenital heart disease codes (Q20–Q28) then they are classified under RHD
  • otherwise, they are counted under nRVD
  • ICD-10 codes I07, I08.2, I08.8 and I08.9 are counted under nRVD.

    ARF is identified by the ICD-10-AM codes I00–I02.