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About the Summary Hospital-level Mortality Indicator (SHMI)


We will be implementing various methodological changes from the May 2024 SHMI publication. Further information is available below in the "SHMI methodological changes from May 2024" section.


The Summary Hospital-level Mortality Indicator (SHMI) reports on mortality at trust level across the NHS in England using a standard and transparent methodology. It was produced and published monthly as a National Statistic by NHS Digital. It continues to be published on this website after NHS England and NHS Digital merged.

The SHMI is the ratio between the actual number of patients who die following hospitalisation at the trust and the number that would be expected to die on the basis of average England figures, given the characteristics of the patients treated there.

The difference between the number of observed deaths and the number of expected deaths cannot be interpreted as the number of avoidable deaths for the trust. The SHMI is not a direct measure of quality of care. The expected number of deaths for each trust is not an actual count of patients, but is a statistical construct which estimates the number of deaths that may be expected at the trust on the basis of average England figures and the characteristics of the patients treated there. 

The SHMI cannot be used to directly compare mortality outcomes between trusts. It is inappropriate to rank trusts according to their SHMI.

Further information about how the SHMI should be interpreted can be found in the "Guidance for users" section below.


Guidance for users


SHMI methodology

The SHMI's specification is founded on an open and transparent methodology. We expect that the SHMI will need to be interpreted, understood and also reproduced by different users. Therefore, we have provided detailed specification documents on the construction of the SHMI and accompanying contextual indicators.

The mapping from ICD-10 diagnosis codes to SHMI diagnosis groups which is referenced in the specification is also available, along with further information on the construction of the provider spells dataset which is used in the calculation of the indicator.


SHMI methodological changes from May 2024

From the May 2024 publication onwards, the following changes will be made to the SHMI methodology:

  • COVID-19 activity will be included if the discharge date is on or after 1 September 2021
  • Hospice sites within non-specialist acute trusts will be excluded
  • In the site level breakdown of the data, a SHMI value will only be calculated for a subset of sites
  • The methodology for identifying the primary and secondary diagnoses for spells consisting of multiple episodes will be updated
  • Activity with an invalid primary diagnosis will be moved to a separate diagnosis group.

Further information on the changes is available in the methodological changes notice (see link below).  An updated version of the SHMI specification is also available.  


SHMI Extract Service for trusts

The SHMI Extract Service provides trusts with an extract of the record-level data which have been used to calculate their SHMI.  Trusts who have registered for this free service have found that receiving the record-level data and accompanying Variable Life-Adjusted Display Charts (VLADs) is very useful, allowing them to better understand their SHMI and to carry out further analysis and investigations into it.  Trusts are only provided with data relating to their trust.  Further information and an application form are available below.  


SHMI research and development

Reports and further analyses carried out by NHS England on the SHMI are published on the SHMI research and development page, along with a methodology development log which contains comments raised on the SHMI methodology and the response to these.  

The SHMI is subject to continuous evaluation and the methodology is currently under review.  For the latest developments in the SHMI review please see the SHMI research and development page.   

Following the recommendations from the national review of the Hospital Standardised Mortality Ratio (HSMR) in 2011, the Department of Health and Social Care commissioned NHS Digital to produce and publish the SHMI.  As part of the review, the Department of Health and Social Care also commissioned independent statistical modelling work, which was carried out by the School of Health and Related Research (ScHARR) at the University of Sheffield and their report is available to download below.


Additional information


Contact us

We welcome further comments on the SHMI, and suggestions for improvement can be sent to [email protected].