This article explains:
HES weighted activity unit (HES WAU) and how it can be used to see productivity
progress over time, including progress within a financial year (‘in-year’)
the difference between the HES weighted activity
unit (HES WAU) and the standard weighted activity unit (WAU)
you can use these metrics to understand and improve your trust’s efficiency
The cost per HES weighted
activity unit (HES WAU) is a measure of absolute efficiency. It’s available
monthly from the Model Hospital and allows you to monitor your trust’s progress
The cost per weighted activity unit (WAU) on
the other hand is a measure of relative efficiency. It’s published on the Model
Hospital annually and is used
to quantify how much it costs to deliver a standardised unit of activity,
compared to other trusts.
These two measures can be used to assess different
aspects of your trust’s efficiency. But you need to be careful about using them
together because they are calculated using different data sources and they
sometimes give different signals because they seek to answer different
WAU: what is a trust’s progress over time (‘absolute’
WAU: what is its performance relative to
others (‘relative’ efficiency)
|Absolute efficiency – best for
tracking the progress of your trust over time
|Relative efficiency – best for
comparing your trust to other trusts
|HES and monthly finance returns
||Reference Costs and annual
between data submission and publication on Model Hospital (approximate)
||6 months +
||· Less activity is covered – the data collected monthly is less comprehensive
than the annual data.
· You can’t compare progress between
trusts, because they report slightly differently.
|· You can’t compare progress over time, because the definition of activity
· Reference costs are not collected
frequently enough to be useful.
· There’s a long time lag before
per HES WAU is used for comparison of efficiency over
time. It’s based on HES (Hospital Episode Statistics) data and monthly finance
returns, which means it can be refreshed more regularly – up to monthly. It
gives a more accurate representation of the absolute efficiency
improvement between years by applying a single categorisation to
patient-level data over time.
per WAU is based on the annual Reference Cost collection.
It allows for a simpler comparison of relative efficiency between
trusts because there is a common reporting standard and less chance
of differences arising from local accounting treatments.
because the cost per WAU uses the national average cost of
each category, any year-on-year changes in average costs and in provider’s mix
of activity mean you can’t compare the cost per WAU over
time. It also has a long lag in reporting (the Model Hospital doesn’t get the
data until about 6 months after the end of each financial year), which means
it’s less useful for tracking progress.
the cost per WAU, the cost per HES WAU is not
suitable for comparing efficiency between trusts. This is because it is constructed
from HES data and monthly finance returns – each collected independently –
and there is potential for mismatch in coverage between cost and activity for
opposed to the yearly cost per WAU measure, cost
per HES WAU is available monthly. While there is a delay between the end of
the month and the availability of this information – up to 3 months – this is
still a much better tool for monitoring progress.
The WAU also
covers more types of acute activity than the HES WAU, including both ‘unbundled
services’ (e.g. chemotherapy, critical care) and some community and mental
health activity. This means that for any one trust, their quantity of HES
WAU will be lower than their quantity of WAU.