Question what they tell you—and how useful they are

Last week (6 April) the Sunday Times published the latest annual assessments of hospital performance compiled by the Dr Foster organisation. Dr Foster claims to provide the “only authoritative and independent guides to UK health services in the public and private sectors” and seeks to “empower consumers and their doctors to make the best possible choices.”1 Dr Foster has brought together a wealth of information, including equipment and services available at each hospital and how the hospital performs on waiting lists and complaints, but its hospital mortality figures will arouse the most interest. Many in the NHS and elsewhere will be asking themselves how they should respond to these data.

Four main questions need a response. Firstly, what do the data actually mean? A hospital does much more than treat inpatients. Over the past decade the scope and nature of ambulatory care provided in hospitals has changed enormously, not only in surgery but also in other specialties such as oncology, where increasingly sophisticated treatments involve a complex mix of inpatient and outpatient episodes.^w1 Moreover, there is good evidence that as the length of the average hospital inpatient episode falls, an increasing proportion of deaths occur outside the hospital.2 Consequently, a measure of outcome looking only at inpatients is a highly selective view of the overall picture.

Secondly, are the results a valid measure of what they purport to be? Compared with previous years^w2 Dr Foster has done much to enhance …