Warrington and Halton Hospitals

Mortality rates

Measures of mortality are an important indication of the quality of care provided by hospitals. They provide information on expected deaths in and out of hospital and measure if a hospital trust is seeing an average, higher or lower than average number of deaths than expected among patients.

We make our latest mortality rates available to you on this page. We also provide sources where you can find out more information on mortality rates.

How is mortality calculated?

Mortality rates are calculated from routinely collected hospital data. There are two key mortality measures used in the NHS:

  • Hospital Standardised Mortality Ratio (HSMR).The HSMR is calculated each month for each hospital in England. It looks at deaths in the most common conditions in hospital which account for around 80% of deaths in hospital
  • Summary Hospital-level Mortality Indicator (SHMI). The SHMI score looks at all deaths in hospital and within 30 days of discharge from hospital.

These scores are constantly being develop to provide a more accurate mortality rate. Mortality rates are used to help regulators identify trusts that may have issues around care. Trusts also use them to drive improvements in services.

How should HSMR and SHMI be interpreted?

These rates use an average base score of 100. Generally speaking a score below 100 means that a trust had fewer deaths than would be expected, given the types of cases treated. Trusts with a rate above 100 will have had more deaths than would be expected. However, trusts with scores higher and lower than 100 can still fall into expected ranges which are usually a score somewhere between 90 and 110 on the measures.

HSMRs and SHMI results do need to be interpreted carefully. They cannot say with any certainty that an exact number of people died or show whether those deaths were as a result of any issues with care. HSMR and SHMI figures are rebased monthly so can also change slightly. However they are part of a number of factors that we can use as a guide to ensuring our care is safe.

How do we score?

Our latest figures (updated February 2018) are:


  • Rolling 12 months score: 101.07
  • We are rated as within expected ranges for HSMR.


  • Rolling 12 months score : 106.78
  • We are rated as within expected ranges for SHMI.

How are we working to further reduce mortality rates?

Actions that the trust has been actively working on to further reduce mortality rates include:

  • Reviewing the trust’s care pathways and best practice care bundles to ensure a high standard of care for every patient, every time
  • Implementation and continual refining (in collaboration with other North West Trusts) of a robust mortality review process and use of the outcomes to drive improvement
  • Improving the management of patients whose condition deteriorates rapidly by introducing a Medical Emergency Team (2015 HSJ award finalists) and the latest ‘early warning score’ tool to make sure we can act as quickly as possible for such patients.
  • Increasingly robust analysis, use and distribution of mortality data (including benchmarking with other trusts) to identify areas requiring further review.
  • Providing data to medics, on their activity and how this benchmarks with local and national peers, as part of their appraisal and revalidation process.
  • Reporting mortality data and HSMR and SHMI ratios to trust board and across the organisation

Want to know more?

There are several useful sources of further reading on mortality rates in the NHS.

  • Health and Social Care Information Centre- HSCIC produce statistics on behalf of the NHS and publish SHMI scores on a quarterly basis outlining trusts who are above and below expected ranges. You can access their latest information here.

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