Editor’s Notebook: Learning by Definition

Learning by Definition

Editor, susan.psqh@gmail.com

Careful use of terminology is essential in patient safety literature. Lucian Leape (1994) takes great care to define terms in his foundational article, “Error in Medicine.” Using the construct originated by James Reason, he defines error as “an unintended act (either of omission or commission) or one that does not achieve its intended outcome” (p. 1851). He then distinguishes among different kinds of errors: slips and mistakes of various kinds, as well as latent and active errors. That may sound fussy, especially to those who are new to the study of human error, but the distinctions are important. At the time, Leape’s audience was not familiar with these concepts, which were developed through the study of cognitive psychology and human factors engineering. Understanding the dynamics behind human error is a crucial first step in safety improvement, one that requires learning new terminology.

In September 2014, coincidentally concurrent meetings—one in Oxford, England; one in Atlanta—discussed new terminologies related to overdiagnosis and diagnostic error. The meeting in Oxford was titled “Preventing Overdiagnosis: Winding back the harms of too much medicine” (http://www.preventingoverdiagnosis.net). This was the second annual meeting sponsored by organizations including The Dartmouth Institute, BMJ, and Consumer Reports. Most sessions focused on research, but one, “Nailing the definition of overdiagnosis,” indicates that they continue to work on terminology even as they work on solving the problem.

The 7th annual Diagnostic Error in Medicine (DEM) conference, held in Atlanta, was sponsored by the Society to Improve Diagnosis in Medicine (SIDM; www.improvediagnosis.org) with support from the Agency for Healthcare Research and Quality. Defining diagnostic error has been on the agenda for at least the past three conferences (which I have attended). While at times the discussion is quite academic, it’s important to discuss and use appropriate definitions and terminologies that lead us to providing the safest care.

This year, DEM considered whether overdiagnosis is a form of diagnostic error, which is most often defined using the definition of SIDM President Mark Graber as a diagnosis that was missed, delayed or wrong. Overdiagnosis is often the result of over-screening, such as in prostate and breast cancers, and might lead to overtreatment, especially if the condition would never have led to harm. Discussion will no doubt continue.

Hardeep Singh also talked about issues of terminology as he introduced a DEM panel discussion about error measurement. The science of diagnostic error prevention is relatively new; reaching consensus about how to define different kinds of errors is important. Singh observed, “We cannot measure what we cannot define.” Improving patient care through rigorous research and error measurement depends upon accepted, clear definitions, especially when current national conversations expect a higher degree of transparency and accountability in healthcare.

Making sure that measurement and, therefore, our definitions account for real-world clinical practice is among the challenges Singh and others discussed at DEM. Diagnosis often evolves in a complex and dynamic real-world setting, and some of its attributes are difficult but not impossible to capture. As was true when Leape parsed definitions of different kinds of medical errors in the 1990s, current discussions about how to define diagnostic error will no doubt lead to improving our understanding of key systems and thought processes on which our lives depend.



Leape, L. (1994). Error in medicine. JAMA, 272(23), 1851–1857.