Using mortality rates to assess the quality of health care is complex because hospitals provide a wide range of services for a wide range of conditions, to patients with very different risks of dying.
About 60 per cent of all deaths take place in hospital. Most of these deaths are inevitable and beyond the control of hospitals. A reliable comparison between hospitals therefore requires the mortality data to be fully adjusted for factors such as age, sex, deprivation and co-morbidities, which do not reflect the quality of care. This may not always be possible. Furthermore, most organisations perform well in some areas and less well in others, adding to the limitations of a single, overall indicator as a measure of quality.
The publication of the Dr Foster Hospital Guide in 2009, which appeared to contradict the findings of other quality assessments, including those of the Care Quality Commission, led to considerable confusion in the NHS and amongst the public.
A heated debate ensued among health care professionals and academics on how reliable and useful hospital-wide mortality rates are as a measure of quality, and the virtues of alternative approaches to measuring quality.
It was against this background that the Department of Health (DH) commissioned a review, of hospital-wide mortality measures. The group, of which I was a member, publishes its report today.
So what's the verdict?
The report, National Quality Board advice and recommendations concludes that mortality rates can be used but with caution and only alongside other indicators of quality. It recommends that a standardised NHS-wide methodology – to be developed during 2011 – is used for calculating the new indicator, the Summary Hospital-level Mortality Indicator (SHMI).
But the report carries its own significant health warnings. In particular, it states that alongside the SHMI, there has to be guidance as to the publication, presentation and use of such data to prevent the level of confusion the publication of hospital-wide mortality rates have caused in the past.
Information can be a powerful tool, both to inform patients about the quality of care provided by different hospitals, and to enable clinicians to drive improvements in quality within their organisations or practice. For example, where mortality rates look high – whether at a service or whole organisation level – they can act as a useful starting point for further investigation. But if used inappropriately, information has the potential to mislead patients and the public, and erode confidence in NHS staff and the organisations they work in.
Despite the solution offered by the DH, it's clear that mortality rates generate, and will continue to generate, significant public interest and professional debate. In the US an expert group has concluded against public reporting of hospital-wide mortality rates because of their inherent unreliability. However, with the Freedom of Information Act, the scandal of Mid-Staffordshire, the move to more open government and the 'information revolution' in health promised by the coalition government, the publication of this indicator (in one guise or another) for English hospitals is unavoidable. Those of us interested in ensuring data serves to improve care and empower patients have an interest in ensuring that its publication is done in the most responsible way possible.