The CHeReL provides advice on the design, cost, feasibility and process of linkage studies. We offer four types of record linkage services:
Biolink is a service of the Centre for Health Record Linkage (CHeReL), offered exclusively to clients of the NSW Health Statewide Biobank (NSWHSB). Using state-of-the-art data linkage methodology and expert advice, Biolink enables the biospecimens stored at NSWHSB to be longitudinally linked with a broad range of routinely collected health data about participants. Linkage to routinely collected data provides an efficient and cost-effective alternative to manual follow up of participants’ health service use and outcomes.
For Collection Custodians and researchers using the NSWHSB, the CHeReL provides a comprehensive data linkage service that includes:
CHeReL has a dedicated Biolink Research Project Manager, who can provide more information on accessing services and access conditions. The Biolink Research Project Manager can be contacted at MOH-Biolink-Cherel@health.nsw.gov.au
The CHeReL can link consenting participants to a broad range of routinely collected data from NSW Health and other administrative or research data collections.
Examples of routinely collected NSW Health data and accompanying data dictionaries can be accessed at /datasets.
A Biospecimen Linked Standardised Data Asset (BLSDA) is being developed to simplify access to linked NSW Health data. The BLSDA will be a core minimum health data asset of linked NSW Health data collections for the participants in a number of strategic biospecimen collections held in the NSWHSB. The NSW Health data asset will be available off the shelf at no cost to eligible researchers. Approval is required in accordance with the Strategic Collection Access Policy available at https://biobank.health.nsw.gov.au/researchers/biospecimen-collection-grants/
Record linkage brings together information that relates to the same individual, family, place or event from different data sources. In this way it is possible to construct chronological sequences of health events for individuals. Combined, these individual 'stories' create a larger story about the health of people in NSW and the ACT.
An example is a study by a research team who want to investigate whether bowel cancer screening can improve survival. To address this question the researchers require information about people’s bowel cancer screening from a survey, as well as their cancer incidence, relevant hospital treatment and deaths that are recorded in administrative data collections managed by government agencies.
Once the relevant government agencies and a human research ethics committee approve the research project, the data can then be securely linked by the CHeReL and made available to the researcher.
The process by which data is securely linked and made available is as follows:
The first step in data linkage is to split the records from each dataset into two separate files. To protect privacy, the identifier information such as names and addresses is separated from the content information, like cancer type or screening history. The two separate files from each dataset are stored and handled separately. The identifier data is used in the Data Linkage process and the content information without names and addresses is used in Data Integration.
CHeReL’s Data Linkage Unit applies a combination of matching methods to the identifier data to identify and distinguish between individuals, e.g. between this John Smith and that John Smith. The identifier data belonging to each individual is then assigned an arbitrary Person Number which replaces the name, address and other identifying details.
Using an encrypted version of the arbitrary Person Number, CHeReL’s Data Integration Unit then makes a research Project specific Person Number for each individual (PPN). A different PPN is created for each research project. This PPN is then joined to the relevant survey, cancer and hospital data that has been approved for the research project by the relevant government agencies and human research ethics committee. All records for an individual in any approved project dataset will have the same PPN. The approved data is released to the researcher, along with conditions on the use of data.
Using the PPN that is attached to the survey, cancer and hospital data, the researcher can combine records for an individual without accessing information about their identity. This helps to ensure that privacy is protected and research in the public interest continues to improve the health system and health outcomes.
The CHeReL currently uses Choicemaker software for linkage.
Choicemaker provides for standardisation and parsing, and differs
from the classical probabilistic approaches and software
primarily in the use of an automated blocking algorithm and machine
learning technique for 'scoring' or assigning weights. The system
also allows users to make use of stacked data (where multiple
values are present in a single field) and includes a "transitivity
engine" that allows for a user-specified action in the case of
transitive linkage problems - for example, if record A is a high
probability match to both B and C, but B and C are low probability
matches to each other. More detail on these features is described
in Goldberg and Borthwick (2004). Additional advantages of
Choicemaker for the CHeReL are that the system is multi-user,
matches in one rather than several steps, is capable of matching
very large files and can be run on variety of platforms.
The Centre for Health Record Linkage charges a fee for the linkage of data. This fee is based on a number of factors, primarily:
The cost of linkage varies for each project. As an example however, the linkage and extraction of records from two MLK datasets for 50,000 individuals would cost approximately $5,000 ex GST. The fee for linkage of an external (i.e. non-MLK) dataset of 10,000 records and subsequent extraction of linked data from two MLK datasets would be approximately $7,000 ex GST. In each example, the cost would increase with the addition of more datasets and individuals. Quotes can be obtained by contacting the CHeReL at
MOH-CHeReL@health.nsw.gov.au or forwarding an Application for Data to the CHeReL.
Please note, the 45 and Up Study may charge a fee for data extraction which is not included in the linkage fee. For more information, please contact the 45 and Up Study at firstname.lastname@example.org.