The National Health Index number (NHI number) is a unique number that is assigned to each person using health and disability support services. The NHI is an index of information associated with that unique number. The NHI holds the following information: name (including alternative names such as maiden names), NHI number, address, date of birth, sex, New Zealand resident status, ethnicity; date of death, and flags indicating any medical warnings or donor information. Clinical information is not recorded on the NHI.

Additional information:

Have_(encrypted)_NHI Yes
Personally identifiable (e.g. linked to NHI numbers) and longitudinal or aggregated (e.g. for planning, clinical research etc.)? Yes - it IS the source of truth
Volume of data (e.g. how many records) Since when? Close to 100% of the population. The first national register was the National Master Patient Index, implemented in 1977. This was replaced with the NHI in 1993. Newborn babies have been registered on the national system since 1992.
Purpose and governance including ethics committee/patient consent mechanisms. Q: How do you get around ethics/privacy issues with your data sources? Esp. DHBs? Mandatory - the Health Information Privacy Code 1994 places restrictions on the creation and use of unique identifiers such as the NHI number.
Scope National
Does the data contain diagnoses and clinical outcomes? Does the data contain procedures, device information and medication for therapy? Does this data set have cost / price data? No -NHI includes only information needed to identify healthcare users, such as name, address (including domicile code), date of birth, sex and ethnicity.
Presence of Data dictionary? Column headings in Excel or any kind of data model if residing in a relational database (e.g. Access, SQL Server, Oracle etc.)
Linked (or linkable) to other datasets within your organisation or across the Sector Yes
How often does this data set get updated? Daily? Weekly? Monthly? Quarterly? Yearly? real-time
Indication of data quality (e.g. missing values, duplications, inconsistencies etc.). Q: Audits? How do you ensure the data is valid and correct? Good - continuously improving. The new Health Identity system is using the state-of-the-art IBM Initiate system's statistical auditing and search functions and reduced duplicates from 14% to 4% in 2012.
Brief info about the systems and processes used to collect/manage data. Q: Where the data is collected, in what form, and accessibility? Old NHI system was running on a legacy platform soon to be retired. The new Health Identity project encapsulates the NHI and HPI as well as continuiing and perhaps extending the use of MWS. There is plans to incorporate current medicines list to that platform. The new system has Webservices based API that is interfacing real-time with clinical and other systems.
Data format, e.g., data structure, data types, and storage form (relational database, Excel, csv, etc.). All structured - as per data dictionary
How well the data is structured, e.g. free text VS coded text VS pick-list (drop-down list) Very good
How quickly can the data be made available from time of request and how old is the data once it is made available with appropriate approval very quickly