SHMI Quarterly Profiling and Forecasting
Date: 06 April 2017
The Summary Hospital-level Mortality Indicator (SHMI) value published by NHS Digital (NHSD) is the one and only figure that should be quoted and, as far as interpretation goes, it is the Band that is paramount. Breaking the SHMI value down by age or CCS Group may help with investigation and understanding but breaking SHMI down by time-periods [months or quarters] can yield spurious results. This is due to two main reasons:
- The modelling period comprises 36 months so is unaffected by seasonality whereas selected months or quarters will be influenced by the seasonal variation in hospital-level mortality
- The same quarter appears in four separate releases and its relative risk changes with each release
However, understanding how data are changing over time, including by quarter, is a useful aid to unravelling the underlying reasons for changes in reported SHMI values. This report explains how to interpret data for individual quarters and how this may be used to anticipate changes in future SHMI values.