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, with each publication reporting on a 12-month period.
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 covers patients admitted to hospitals in England who died either while in hospital or within 30 days of being discharged. Deaths related to COVID-19 are excluded from the SHMI.
To help users of the data understand the SHMI, trusts have been categorised into bandings indicating whether a trust's SHMI is 'higher than expected', 'as expected' or 'lower than expected'. For any given number of expected deaths, a range of observed deaths is considered to be 'as expected'. If the observed number of deaths falls outside of this range, the trust in question is considered to have a higher or lower SHMI than expected.
Further background information and supporting documents, including information on how to interpret the SHMI, are available on the SHMI homepage at https://digital.nhs.uk/SHMI