Using linked data to identify people living with dementia

The National Integrated Health Services Information (NIHSI) is a person-focused, de-identified analytical asset that allows for a range of research and analysis on many aspects of population health through access to standardised integrated health administrative datasets (AIHW NIHSI 2020–21). The NIHSI is the only enduring linked data asset that includes linked hospital data including admitted patient care services, emergency department services and outpatient services in public hospitals for New South Wales (NSW), Victoria, Queensland, South Australia, Tasmania and the Australian Capital Territory (ACT).

The NIHSI includes various national Commonwealth government datasets, including the Pharmaceutical Benefits Scheme (PBS) and Repatriation PBS (RPBS), Medicare Benefits Schedule, National Non-Admitted Patient Emergency Department Care Database (NNAPEDC), National Hospital Morbidity Database (NHMD), Residential Aged Care Services data and National Death Index (NDI) data. The NIHSI contains data from 2010 until 2020–21.

Data linkage for the NIHSI was undertaken using probabilistic linkage. This linkage procedure involves creating record pairs by combining records from one data set with records from another data set based on similarities in characteristics such as last and first name(s); day, month and year of birth; and sex. The Medicare Consumer Directory and the NDI were first linked to create the NIHSI linkage spine.

In this study, a person was identified as having dementia if they were aged 30 or over and had at least one of the following in the NIHSI between 1 July 2010 and 31 December 2018:

  • a dementia-specific medication dispensed through the PBS / RPBS,
  • a principal or additional diagnosis of dementia in an emergency department (ED) presentation or public hospital admission,
  • a supplementary chronic code of dementia in a public hospital admission,
  • a record of dementia in an Aged Care Funding Instrument (ACFI) assessment, and/or
  • dementia recorded as an underlying or additional cause of death between January 2020 and December 2021.

The study cohort was also restricted to people who were:

  • alive until 31 December 2019
  • recorded in the NIHSI as using a health service in 2019, or having a death record January 2020 – December 2021
  • not missing age, sex and/or geography information.

Tables 1–4 summarise the codes used in each dataset to identify dementia and the classification system used in each dataset. For more details, see the Data sources section of Dementia in Australia (AIHW 2023). 

Table 1: List of health condition codes used to identify dementia in the ACFI dataset
SourceDementia-specific codes
Aged Care Assessment Program (ACAP) health condition code0500, 0510, 0520, 0530
Table 2: List of diagnosis codes used to identify dementia in the NHMD and NNAPEDC datasets
SourceDementia-specific codes 
Admitted patient ICD-10-AM diagnosis codesF00, F01, F02, F03, F05.1, F10.7, F13.7, F18.7, G30
Admitted patient chronic condition supplementary codeU791
Emergency department ICD-10-AM diagnosis codesF00, F01, F02, F03, F05.1, F10.7, F13.7, F18.7, G30
Emergency department ICD-9-CM diagnosis codes290.0, 290.1, 290.10, 290.11, 290.12, 290.13, 290.2, 290.20, 290.21, 290.3, 290.4, 290.40, 290.41, 290.42, 290.43, 290.8, 290.9, 291.2, 294.1, 294.10, 294.11, 294.2, 294.20, 294.21, 331.0 
Emergency department SNOMED CT-AU EDRS diagnosis codes52448006, 12348006, 15662003, 26929004, 191461002

Note: ICD-10 refers to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision. ICD-10-AM refers to ICD-10, Australian Modification; ICD-9-CM refers to the ICD, Ninth Revision, Clinical Modification; SNOMED CT-AU EDRS refers to the Systematized Nomenclature of Medicine - Clinical Terms - Australian version (Emergency Department Reference Set).

 Table 3: List of diagnosis codes used to identify dementia in the National Death Index dataset
SourceDementia-specific codes
ICD-10 Underlying or associated cause of death codesF00, F01, F02, F03, F05.1, F10.7, F13.7, F18.7, G30, G31.0, G31.8
Table 4: List of codes used to identify dementia in the Pharmaceutical Benefits Scheme dataset
SourceClassification and dementia-specific codes
Classification and dementia-specific codes

N06DA02 (donepezil), N06DA03 (rivastigmine), N06DA04 (galantamine) 

N06DX01 (memantine)  

References

AIHW (Australian Institute of Health and Welfare) NIHSI (2020–21) National Integrated Health Services Information, AIHW, Australian Government, accessed 26 July 2023.

AIHW (2023) Dementia in Australia, AIHW, Australian Government, accessed 11 April 2023.

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