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. It includes deaths which occurred in hospital and deaths which occurred outside of hospital within 30 days (inclusive) of discharge.
The SHMI gives an indication for each non-specialist acute NHS trust in England whether the observed number of deaths within 30 days of discharge from hospital was 'higher than expected' (SHMI banding=1), 'as expected' (SHMI banding=2) or 'lower than expected' (SHMI banding=3) when compared to the national baseline.
Trusts may be located at multiple sites and may be responsible for 1 or more hospitals. A breakdown of the data by site of treatment is also provided.
The SHMI is composed of 144 different diagnosis groups and these are aggregated to calculate the overall SHMI value for each trust. The number of finished provider spells, observed deaths and expected deaths at diagnosis group level for each trust is available in the SHMI diagnosis group breakdown files. For a subset of diagnosis groups, an indication of whether the observed number of deaths within 30 days of discharge from hospital was 'higher than expected', 'as expected' or 'lower than expected' when compared to the national baseline is also provided.
Details of the 144 diagnosis groups can be found in Appendix A of the SHMI specification.
Notes:
1. There is a shortfall in the number of records for Buckinghamshire Healthcare NHS Trust (trust code RXQ), Mid Cheshire Hospitals NHS Foundation Trust (trust code RBT) and Torbay and South Devon NHS Foundation Trust (trust code RA9). Values for these trusts are based on incomplete data and should therefore be interpreted with caution.
2. Due to a problem with the process which links Hospital Episode Statistics (HES) data to the Office for National Statistics (ONS) death registrations data, some in-hospital deaths have been counted as survivals in a small number of trusts. This affects 126 spells in the May 2025 to April 2026 time period for Wirral University Teaching Hospital NHS Foundation Trust (trust code RBL) meaning that the number of observed deaths has been underestimated and so the results for this trust should be interpreted with caution. For the other trusts, the number of affected spells (and hence the impact on the SHMI) is small.
3. There is a high percentage of invalid diagnosis codes for Blackpool Teaching Hospitals NHS Foundation Trust (trust code RXL), Bradford Teaching Hospitals NHS Foundation Trust (trust code RAE), Buckinghamshire Healthcare NHS Trust (trust code RXQ), County Durham and Darlington NHS Foundation Trust (trust code RXP), Nottingham University Hospitals NHS Trust (trust code RX1), Portsmouth Hospitals University NHS Trust (trust code RHU), The Princess Alexandra Hospital NHS Trust (trust code RQW), University Hospitals Birmingham NHS Foundation Trust (trust code RRK) and West Suffolk NHS Foundation Trust (trust code RGR). Values for these trusts should therefore be interpreted with caution.
4. On 1st July 2026, North Bristol NHS Trust (trust code RVJ) was acquired by University Hospitals Bristol and Weston NHS Foundation Trust (trust code RA7). The new organisation is called Bristol NHS Foundation Trust (trust code RA7). In this publication, data are still presented for the two separate organisations. Data will be presented for the new trust at a later date.
5. There are variations between trusts in the recording of same day emergency care (SDEC). Where trusts are submitting SDEC activity as part of the Outpatient dataset or Emergency Care Data Set (ECDS) rather than the Admitted Patient Care (APC) dataset or are recording this activity as day cases within the APC data, these records will not be included in the SHMI. Trusts with SDEC activity removed from the SHMI data have seen an increase in their SHMI value. As all trusts are expected to transition to recording SDEC activity as admitted patients, the data will become more comparable over time and the impact on the SHMI will reduce.
6. Further information on data quality can be found in the SHMI background quality report, which can be downloaded from the 'Resources' section of this page.