Frequently Asked Questions

The Centre for Health Record Linkage (CHeReL) charges a fee for the linkage of records. The cost varies based on the cohort size and the number and types of datasets being linked. Please note CHeReL prices for the cost of linkage of NSW and ACT data only. Other data linkage units, data custodians and data storage services may also charge their own fees.

Please review the Data Linkage Costs page on our website.

Linked NSW data may only be stored within a Secure Access Environment and may not be stored anywhere else. Copies of linked data may not be stored on local servers, or any portable devices including external drives, laptops or desktop computers.

No. If you are after unlinked data from an administrative dataset, for example you are only interested in hospitalisation data, you will need to contact the relevant data custodian of that dataset.

Data variables available for analysis are listed in the published data dictionaries.

You will need to contact the data custodians of external datasets to request data dictionaries and variable lists of other datasets.

No. CHeReL cannot advise what variables should be used to answer your research questions.

In planning a research study, researchers should seek advice from colleagues who have worked with linked data before. Researchers should also consult the published data dictionaries to understand the format and function of each variable.

No. CHeReL cannot advise researchers on which diagnosis or intervention codes are appropriate for use in their studies. Researchers should engage with a Health Information Manager or Clinical Coder at their institution for assistance.

Socio-Economic Indexes for Areas (SEIFA) and Remoteness Area (RA) mapping files are available for download from the Australian Bureau of Statistics.

Data collections which are routinely geocoded to include Statistical Areas (SA1 or SA2) are compatible with these SEIFA/RA mapping files.

Yes. CHeReL can link external datasets. To do so we require suitable identifiers for linkage and approvals from the data custodian of the dataset.

No. CHeReL undertakes data linkage for projects utilising NSW and ACT data collections.

However we do work closely with other jurisdictional data linkage units to facilitate cross- and multi- jurisdictional linkage via the Population Health Research Network (PHRN).

Information about datasets available for linkage across Australia is also available on the PHRN website.

No. All linked data must be de-identified and all efforts are to be made to mitigate the risk of re‑identification of data.

The Data Separation Principle should be upheld, such that no one working with de‑identified linked data can view both the identifying information (such as name, address, date of birth) together with the merged analysis (content) data (such as clinical information, benefit details etc) in a linked dataset.

No. Linked data must always be de-identified.

When consent is provided, this consent applies only to the process of data linkage, but that the consent does not extend to their data being linked and provided in identifying manner.

No. You may not receive identified administrative information including clinical information for a specific patient via CHeReL.

CHeReL may only release de-identified linked unit record data for ethics approved research projects.

If you require additional clinical information for your patient, you may wish to speak with your patient directly, or access data via their My Health Record where available.

Clinical trial recruitment and data collection can take some time. We recommend you contact CHeReL once you have completed recruitment for your clinical study.

You should contact NSW Population & Health Services Research Ethics Committee (PHSREC) when planning your clinical trial to obtain advice around seeking consent for data linkage, which may impact the design of your Patient Information Consent Form.

CHeReL uses combinations of identifying information to identify and link individuals’ records.

The following identifiers are recommended:

• Surname
• Given name(s) including middle name(s) if available
• Statistical Linkage Key (if name is not available)
• Sex
• Date of birth
• Street address
• Suburb/locality
• Postcode
• Event date (admission, test, notification, diagnosis etc. this is a date by which the data can be filtered, and is relevant to the record)
• A unique record number

In addition, the following are recommended, where available:

• Person ID / patient ID / Client ID
• Hospital code (for medical records)
• Medical Record Number (for medical records) in combination with facility identifiers and presentation dates

Please note that in general, CHeReL prefers to receive all data including both identifiers and content/clinical data to be linked, de-identified then supplied to the researcher’s secure access environment or approved analytical data storage environment together with NSW administrative data.

Where this is not possible, CHeReL can receive identifiers only.

The application process is iterative and may take considerable time from the submission of an application to the receipt of data.

This depends on how quickly a project is deemed technically feasible and receives all necessary Data Custodian and HREC approvals. Note that while CHeReL can assist researchers with obtaining NSW Data Custodian approvals, we do not have oversight of their responsiveness.

Only once all approvals are in place, a linkage is placed in the queue for linkage. The duration of linkage itself depends on both the availability of resourcing, and the complexity of your linked data request, data quality, cohort size, number of datasets etc.

Exceptional circumstances, such as an escalation for further review, failure of an applicant to respond to feedback, or delays in the provision of external data, may warrant a longer timeframe.

Please allow plenty of time for the approval process and data extract to be completed.

Research studies utilising linked data must be approved by a specialist data linkage Human Research Ethics Committee (HREC).

Studies using linked unit record data comprising personal and health information from only NSW data collections are required to be reviewed by the NSW Population & Health Services Research Ethics Committee (PHSREC).

Studies using linked unit record data comprising personal and health information from only ACT data collections require ACT Health HREC approval.

Multi-jurisdictional data linkage studies that include NSW Health data may be reviewed by any of the specialist data linkage HREC nominated by States and Territories participating in the National Mutual Acceptance Scheme (NMA) for multi‑jurisdictional data linkage studies. Please download the NMA Data Linkage Guide for an up-to-date list of all specialist linkage HRECs.

Please refer to the Amendment Requirements listed on NSW Population & Health Services Research Ethics Committee (PHSREC)’s website

CHeReL and NSW data custodians may be required to review your amendment prior to submission to PHSREC. To do so, you should submit to CHeReL:

• CHeReL combined protocol and application for data (with tracked changes)
• Amendment request form   
• Where there are personnel changes, a PHSREC Change in Personnel form
• Any other project documentation that has changed (variable lists, NSW privacy form, updated HREA etc)

No. The data requested and approved for one project is for the use for that project and accessed only by those researchers named and approved in that project. The linked data cannot be used for additional projects outside of the scope of the original project.

The NSW Ministry of Health is to be acknowledged in any publication or report that arises from the use of the NSW Health data.

Similarly, CHeReL should be acknowledged in any publication for undertaking the data linkage.

There is no prescribed wording to acknowledge the NSW Ministry of Health or CHeReL.

A copy of any publication or report is to be provided to the NSW Ministry of Health at least two weeks prior to public release, emailed to moh-cee@health.nsw.gov.au.

Please refer to your project’s Authority to Disclose documentation for publication notifications specific to your project.