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 Barking, Havering and Redbridge University Hospitals NHS Trust (trust code RF4), Buckinghamshire Healthcare NHS Trust (trust code RXQ), East Suffolk and North Essex NHS Foundation Trust (trust code RDE), Mid Cheshire Hospitals NHS Foundation Trust (trust code RBT), Sheffield Teaching Hospitals NHS Foundation Trust (trust code RHQ), and The Shrewsbury and Telford Hospital NHS Trust (trust code RXW). Values for these trusts are based on incomplete data and should therefore be interpreted with caution.
2. There is a high percentage of invalid diagnosis codes for Blackpool Teaching Hospitals NHS Foundation Trust (trust code RXL), Buckinghamshire Healthcare NHS Trust (trust code RXQ), County Durham and Darlington NHS Foundation Trust (trust code RXP), Harrogate and District NHS Foundation Trust (trust code RCD), Nottingham University Hospitals NHS Trust (trust code RX1), Portsmouth Hospitals University NHS Trust (trust code RHU), Royal United Hospitals Bath NHS Foundation Trust (trust code RD1), The Princess Alexandra Hospital NHS Trust (trust code RQW), The Queen Elizabeth Hospital, King’s Lynn, NHS Foundation Trust (trust code RCX), Torbay and South Devon NHS Foundation Trust (trust code RA9), University Hospitals Birmingham NHS Foundation Trust (trust code RRK), University Hospitals of Morecambe Bay NHS Foundation Trust (trust code RTX), University Hospitals of North Midlands NHS Trust (trust code RJE), University Hospitals Plymouth NHS Trust (trust code RK9), West Suffolk NHS Foundation Trust (trust code RGR) and Wirral University Teaching Hospital NHS Foundation Trust (trust code RBL). Values for these trusts should therefore be interpreted with caution.
3. On 1st April 2026, Bridgewater Community Healthcare NHS Foundation Trust (trust code RY2) was acquired by Warrington and Halton Teaching Hospitals NHS Foundation Trust (trust code RWW). The new organisation is called North Cheshire and Mersey NHS Foundation Trust (trust code RWW). Bridgewater Community Healthcare NHS Foundation trust does not submit activity to HES APC so the impact on the SHMI is minimal, although mapping their data to the new trust, for completeness, will be done at a later date.
4. A number of trusts are now submitting Same Day Emergency Care (SDEC) data to the Emergency Care Data Set (ECDS) rather than the Admitted Patient Care (APC) dataset. The SHMI is calculated using APC data. Removal of SDEC activity from the APC data may impact a trust’s SHMI value and may increase it. More information about this is available in the Background Quality Report.
5. 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.