Annual updates to WAU and other reference cost metrics

Each year NHS providers submit a data set called reference costs, which are used in the calculation of a very large number of Model Hospital metrics, including all the weighted activity unit (WAU) and cost per WAU metrics.

This article tells you the general process for making annual updates using this data. You can also read about the 2017/18 update specifically.

There is a time lag between the end of a financial year and when we update these metrics in the Model Hospital, to allow for submission and checking of the data, and analysing and processing it into Model Hospital metrics. Other factors are also involved – most WAU metrics, for example, are combined with other data sets like the Electronic Staff Record and trust accounts. If there are any delays or problems with this data, Model Hospital updates can get delayed. Sometimes there are changes to the coding of reference costs, or lots of trusts have merged or been reconfigured, which can add extra complexity to some of the tasks.

The approximate timetable is:

  • End of financial year - April
  • Trust deadline for submitting reference costs for previous financial year – August
  • Initial review and processing by NHS Digital, NHS England and NHS Improvement - September
  • Trusts have an opportunity to re-submit reference costs – September / October
  • Reference costs supplied to Model Hospital team for combining with other data and processing into metrics – October / November
  • Publication of updated WAU and other metrics based on reference costs – November / December

All registered users will get alerts from the Model Hospital team when the updated metrics are published.

Find out more about costing collection guidance and how we handle trust mergers and acquisitions.


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