• adverse events, epidemiology and detection
• evaluation methodology
• healthcare quality improvement
• health services research
• patient safety

Insanity—doing the same thing over and over again, and expecting different results.1

Anyone who has received or delivered care understands it is vulnerable to fail. After each failure, the narrative is familiar and recited often—continuous quality improvement is invoked, and performance measurement is touted as a core strategy. Yet, does any of this make a difference?

Almost 20 years ago the Institute of Medicine published ‘To Err is Human’, a widely cited report that highlighted the all-too-frequent occurrence of adverse events, negative and unintended consequences of healthcare.2 An estimated 1 in 10 hospital admissions results in an adverse event3 and 98 000 deaths occur per year as a consequence of adverse events.2 4 In addition to the human cost, adverse events burden the healthcare system—they increase hospital length of stay by an average of 10 days and cost in excess of $414 million per year.5 It is hard to know just how safe care is. Measuring safety is imperfect and there is little evidence that it makes care safer. But we have an ethical imperative to do no harm, which requires us to understand how safe care actually is. Measurement is therefore needed, because after all, we cannot fix or improve what we do not measure.

Despite several commentaries discussing the advantages of existing methods to measure adverse events, controversy about the best method remains.6–16 Many resources have been devoted to determining the most valid method for detecting adverse events, and even more resources have gone towards implementing these measurement approaches within organisations. Discouragingly, however, these approaches have done little to improve the safety of care.17 18 Unlike previous discussions, we submit that the volume and complexity of patient–healthcare system interactions necessitates the development of new, more efficient yet accurate methods for detecting adverse events …