We thank Dr. Hamilton for the critique of “Undesirable Diagnostic Events1 (UDEs),” a concept we recently proposed to advance knowledge on how to standardize the identification of situations with potential diagnostic errors. Dr. Hamilton describes multiple potential confounders influencing the diagnosis of infectious conditions, especially epidemiologic factors and asserts that the heterogeneity of presentation within a given syndrome, such as meningitis, is so broad that comparison of the diagnostic process between centers and countries is likely to be limited. We agree that heterogeneity in the presentation and diagnosis of many conditions could limit widespread applicability. To account for diagnostic processes that vary widely across markedly different health systems and regions, it may be more logical that data about specific UDEs be shared among organizations where disease presentations and diagnostic approaches are similar enough to be validly compared. This can also provide valuable baseline data on the extent of that heterogeneity.

However, we believe the UDE framework can be broadly applicable to the disease in question such that, when applied, will still yield helpful information. For example, acute bacterial meningitis usually presents with one or more of a few common symptoms - such as fever, neck stiffness, altered mental status and/or headache - no matter the bacteriological cause.2 Thus, having a UDE that is based on some of the common presenting features of a certain disease would likely be most useful. As we acknowledge in our manuscript, UDE development and refinement will take additional work. But once candidate UDE conditions are identified, health systems and national organizations can identify situations that meet the specified criteria as a means to track changes in diagnosis over time and measure the impact of quality improvement interventions. In sum, our framework is by no means comprehensive or foolproof, but represents an actionable first step in measuring diagnostic safety in actual practice.