What do hospital mortality rates tell us about quality of care?: Table 1

Abstract

Hospital mortality rates could be useful indicators of quality of care, but careful statistical analysis is required to avoid erroneously attributing variation in mortality to differences in health care when it is actually due to differences in case mix. The summary hospital mortality indicator is currently used by the English National Health Service (NHS). It adjusts mortality rates up to 30 days after discharge for patient age, sex, type of admission, year of discharge, comorbidity, deprivation and diagnosis. Such risk-adjustment methods have been used to identify poor performance, most notably at mid-Staffordshire NHS Foundation Trust, but their use is subject to a number of limitations. Studies exploring whether variation in risk-adjusted mortality can be explained by variation in healthcare have reached conflicting conclusions. Furthermore, concerns have been raised that the proportion of preventable deaths among hospital admissions is too small to produce a reliable 'signal' in risk-adjusted mortality rates. This provides hospital managers, regulators and clinicians with a considerable dilemma. Variation in mortality rates cannot be ignored, as they might indicate unacceptable variation in healthcare and avoidable mortality, but they also cannot be reliably used to judge the quality of healthcare, based on current evidence.

The correlation between National Health Service trusts' clinical trial activity and both mortality rates and care quality commission ratings: a retrospective cross-sectional study

“…13 There have long been discussions on the merit of a mortality index as an indicator of healthcare quality, and some are of the opinion that they cannot be used as an indicator as such. 12,14 Despite having its critics, the SHMI was deemed the most suitable outcome measure to assess if we could corroborate Ozdemir's findings, because it is available for all English NHS hospital Trusts; an added benefit is that it is published per Trust rather than per hospital. It does however highlight that mortality alone may not be sufficient when assessing the potential impact that clinical research may have on organisationwide performance.…”

Retrospective observational study of emergency admission, readmission and the ‘weekend effect’

“…6 However, these inpatient population studies included groups in the denominator which could have a lower short-term risk of death such as hospital transfers and direct ward admissions from primary care, and did not count deaths occurring in the community after discharge. 21 As there are many factors which could influence inpatient mortality, it is important that future reports clearly define the patient groups contributing towards outcomes in order to allow fair comparison and identify mechanisms that may be responsible for temporal trends.…”

Investigating the relationship between quality of primary care and premature mortality in England: a spatial whole-population study

“…The apparent lack of large effect on mortality over the medium term may suggest that the QOF may not have been an optimal investment of health service resources, but mortality rates need to be further investigated within primary care practices, accounting for the quality of local secondary care services. 58 If incentive schemes continue to be used in primary care with the intention of improving population outcomes, indicators will need to be reconsidered and better aligned with evidence on which activities contribute to reduction of premature mortality.…”