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Mortality measurement: understanding the merits of each measure is the key to best practice

When the Princess Alexandra NHS Trust recently published its annual report, its mortality rate was a focus of attention. Unsurprisingly, most NHS trust boards spend time on mortality rates as they are one way of benchmarking hospitals. So, while mortality statistics clearly do not paint a complete picture, they have become linked to the assessment of an organisation’s ability to care for its patients.

Mortality data can also provide organisations with valuable insights that form the basis for improvement, both trust-wide and at consultant level. Measuring mortality accurately is, therefore, vital.

In England, there are currently three risk adjusted hospital mortality measures in use: two in-hospital mortality indicators – HSMR and RAMI – and one newer indicator, SHMI, which includes patients who die in hospital, or within 30 days of discharge.

All risk-adjusted mortality measures take into account case mix but vary in their selection of other factors. Different indicators will suit different analyses, so there are times when it may be better to use one measure instead of another, depending on the circumstances within a hospital or department, and measures can also be used together to gain further insight.

The nuances between the measures are not well known however, and selecting the factors that need to be considered is complex. NHS boards and commissioners may be tracking all three, which is time consuming, but this need not be the case. When used appropriately, one measure can enable trusts to identify opportunities for improvement and, ultimately, reduce mortality rates.

In deciding which measure to use and interpreting the results, it is crucial to understand what each measure takes into account in its calculation of expected deaths, each measure bringing its own individual strengths and limitations.

CHKS has analysed the differences between these three mortality measures and the underlying methodologies, so that users may be better equipped to choose the right one for their mortality assessment. CHKS is not advocating the use of one measure over another but providing guidance on when these three measures should be employed. The CHKS report is an essential manual for boards looking to establish which mortality measure will work most effectively for them.

You can download the CHKS hospital mortality measures report here.

Please contact the CHKS team for any queries using the details here.

Dr Charles Young

CAPITA Healthcare Solutions