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About the Summary Hospital-level Mortality Indicator (SHMI)
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 is produced and published monthly as a National Statistic by NHS Digital.
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
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 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.
COVID-19 activity in the SHMI
As of the July 2020 publication (covering discharges in the period March 2019 - February 2020), COVID-19 activity has been excluded from the SHMI. The SHMI is not designed for this type of pandemic activity and the statistical modelling used to calculate the SHMI may not be as robust if such activity were included.
If any of the episodes within a provider spell have a COVID-19 diagnosis code, then the spell is excluded from the SHMI. Additionally, for deaths included in the SHMI, if COVID-19 is recorded anywhere on the death certificate, then the death and the spell it is linked to are excluded from the SHMI. This 2nd exclusion is necessary as the SHMI also includes deaths which occurred outside of hospital within 30 days of discharge.
Activity that is being coded as COVID-19, and therefore excluded, is monitored in the contextual indicator 'Percentage of provider spells with COVID-19 coding'.
Further information about the exclusion can be found by following the ‘SHMI methodological changes’ link in the ‘Resources' section below.
Please note that there was a very small amount of COVID-19 activity in the data included in the May 2020 and June 2020 SHMI publications but this did not have a significant impact on the results.
SHMI research and development
Reports and further analyses carried out by NHS Digital 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 NHS Digital's 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.
We welcome further comments on the SHMI, and suggestions for improvement can be sent to firstname.lastname@example.org.