NHS Data Model and Dictionary Retirement Guidance

The NHS Data Model and Dictionary contains classes, attributes, data elements, NHS business definitions and supporting information, relating mainly to data sets which have been approved over time by the Information Standards Board for Health and Social Care, Standardisation Committee for Care Information (SCCI), Data Coordination Board (DCB) and Data Alliance Partnership Board (DAPB).

During development of new data sets, or changes to existing data sets, it may be necessary to ‘retire’ these entities in their entirety, or to retire parts of their associated definitions or National Code lists.

Retirement may also be undertaken when:

• an entire item, such as a data set, no longer has a national requirement to flow (by, for example, the Department of Health or other original owner), or
• where subdivision of National Codes is required for improved national reporting. In the latter case, the original existing National Code would be retired (to maintain its integrity for historical analysis), and new National Codes created

The NHS Data Model and Dictionary is required to indicate where an item used to be a national standard, but that item has been retired. This is to enable historical analysis and research work to continue to be supported.

However, it is critical that ‘old’ definitions and entities are not assumed to be still active by the customers of the NHS Data Model and Dictionary. Items related to the retired item (for example, Data Elements which were once used in the retired data set, and remain active in the NHS Data Model and Dictionary in use in other data sets), should also retain their integrity in the context of the retired item.

The NHS Data Model and Dictionary is required to indicate where an item used to be a national standard, but that item has been retired. This is to enable historical analysis and research work to continue to be supported. However, it is critical that ‘old’ definitions and entities are not assumed to be still active by the customers of the NHS Data Model and Dictionary, and that items related to the retired item (for example, Data Elements which were once used in the retired data set, and remain active in the NHS Data Model and Dictionary in use in other data sets), also retain their integrity in the context of the retired item. For example, if an active Data Element’s definition has changed since it was used in a retired data set, some customers of the NHS Data Model and Dictionary Service may assume that the current live definition was also valid at the time the retired data set was active, where this might well not be the case.

In order to mitigate these risks, the NHS Data Model and Dictionary Service have developed a mechanism to archive previous versions of the NHS Data Model and Dictionary. The definitions of items which have been retired are replaced with a page informing the customer that the item is retired and directing them to the appropriate archived version of the NHS Data Model and Dictionary, if access to the item and the definitions of its components at the time of retirement is required.

2.1 Whole item retirement

This process is used where an entire class, attribute, data set, data element, NHS business definition, or supporting information page is retired from the NHS Data Model and Dictionary.

This is only possible, for example:

• where the item is not used by more than one data set
• where an item is used in more than one data set, its definition remains as it stands, but links to it are broken by the retirement of the overall data set

In this scenario, the existing definition or layout page of the item is replaced by a standard format archive page, which states the following (with appropriate explanatory text within the <> brackets):

An example of this is shown below:

In addition to this, the item is also ‘retired’ from its usual place in the menu structure of the NHS Data Model and Dictionary and is only accessible via the ‘All Items Index’ or through a Search on content.

2.2 Single national code retirement

Where one or more National Codes within an Attribute are to be retired, but the Attribute itself remains active, a different process is undertaken. In this case, the codes are ‘greyed out’ and notation added as to the date of their retirement. This date aligns to the implementation date of the associated Information Standard and Collection (including Extraction).

2.3 Archived versions

Below is an example of the watermarking applied to archived versions of the NHS Data Model and Dictionary, which will indicate to the user that it is an old version.

Access to the appropriate archived version is obtained by emailing the NHS Data Model and Dictionary Service at information.standards@nhs.net, so that detailed instructions can be given and usage monitored.