• Accreditation
• Adverse events, epidemiology and detection
• Ambulatory care

Over more than a decade of widespread attention to medical error and patient safety, a small group of academicians lamented that diagnostic errors have been relatively underemphasised and received ‘no respect’ in the larger conversation about improving care.1–3 In response, this dedicated group organised the annual Diagnostic Error in Medicine (DEM) conferences with support from the US Agency for Healthcare Research and Quality.4 The goal of the DEM conference (now in its 6th year)5 is to promote a better understanding of diagnostic error and to foster the creation of novel intervention strategies to improve the quality of diagnosis. Thus far, the DEM conferences have successfully united researchers and other experts in the field of diagnostic error, practitioners from a variety of clinical and non-clinical specialties, educators, patients, informaticians and several national stakeholders. This month's supplement to BMJ Quality and Safety reflects the novel scholarship and synthesis of knowledge that have been shaped through the DEM forum presentations and discussions specifically over the past 3 years.

At the outset, I would like to thank the 30 anonymous reviewers, many of whom are experts from outside the field of diagnostic error, who helped strengthen the contributions to this supplement. Their comments helped improve the rigour and overall quality of the papers. As a result of the contributors’ and reviewers’ hard work, this supplement offers a critical, up-to-date summary of the current state of the science for diagnostic error. Although the science is still early in its development, I am confident that these contributions will promote engagement between the diagnostic error community and others with a stake in improving the quality of healthcare.

Historically, diagnostic errors have been on the sidelines of patient safety research, in part because we do not have good estimates on how common these events are relative …