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Data set, Part of

SHMI site change during spell contextual indicator


This indicator is designed to accompany the SHMI data at site of treatment level.

The SHMI is calculated at the level of the provider spell, which is a continuous period of time spent as a patient within a single trust (provider). A spell may be composed of more than 1 episode (a single period of care under 1 consultant). If a patient is moved between hospitals or sites within the same trust, the provider spell continues. Most spells consist of a single episode and so there is no complication when presenting SHMI data at site level because the entire provider spell occurred at a single site. However, spells consisting of multiple episodes may have occurred over multiple sites and only 1 of these sites can be associated with the spell. This has been chosen to be the site of the 1st episode in the spell. This may result in hospital deaths being attributed to a site other than the one in which they occurred, with an impact on the SHMI values presented for the sites concerned. This impact is likely to be greater for sites within trusts showing higher percentages for this contextual indicator.

This indicator is being published as an experimental statistic. Experimental statistics are official statistics which are published in order to involve users and stakeholders in their development and as a means to build in quality at an early stage.


1. As of the July 2020 publication, 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. 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' which is part of this publication.

2. Please note that there has been a fall in the overall number of spells due to COVID-19 impacting on activity from March 2020 onwards and this appears to be an accurate reflection of hospital activity rather than a case of missing data. Further information is available in the contextual indicator ‘Provider spells compared to the pre-pandemic period’ which is part of this publication.

3. A large proportion of records for Mid and South Essex NHS Foundation Trust (trust code RAJ) have missing or incorrect information for the main condition the patient was in hospital for (their primary diagnosis) which affects data between April 2020 and March 2021. Due to the impact of this on the underlying SHMI models, all data for this trust has been excluded. Work is ongoing to correct the underlying data for this trust and once complete it will be included in future publications.

4. Day cases and regular day attenders are excluded from the SHMI. However, some day cases for University College London Hospitals NHS Foundation Trust (trust code RRV) have been incorrectly classified as ordinary admissions meaning that they have been included in the SHMI. Maidstone and Tunbridge Wells NHS Trust (trust code RWF) has submitted a number of records with a patient classification of ‘day case’ or ‘regular day attender’ and an intended management value of ‘patient to stay in hospital for at least one night’. This mismatch has resulted in the patient classification being updated to ‘ordinary admission’ by the Hospital Episode Statistics (HES) data cleaning rules. This may have resulted in the number of ordinary admissions being overstated. The trust has been contacted to clarify what the correct patient classification is for these records. Values for these trusts should therefore be interpreted with caution.

5. On 1 October 2021 Pennine Acute Hospitals NHS Trust (trust code RW6) merged with Salford Royal NHS Foundation Trust (trust code RM3). The new trust is called Northern Care Alliance NHS Foundation Trust (trust code RM3). However, as we received notification of this change after data processing for this publication began, separate indicator values have been produced for this publication. This will be updated in future publications to reflect the new organisation structure.

6. There is a shortfall in the number of records for Countess of Chester Hospital NHS Foundation Trust (trust code RJR) meaning that values for this trust are based on incomplete data and should therefore be interpreted with caution.

7. Further information on data quality can be found in the SHMI background quality report, which can be downloaded from the 'Resources' section of the publication page.