Whenever possible, but especially if data are to be compared across institutions, standards for data in an adverse event system should describe how the data elements should be collected. Descriptions of patient populations that should be included or excluded and specification of whether a patient may be included multiple times during the same encounter will help clarify the group to be investigated. Data sources—including reports from health care providers’ hospital discharge summaries, emergency department notes, computer triggers, electronic clinic notes, and administrative incident reports—should be described.

Uniformity of systems and applications for collecting the data (such as surveys, interviews, or claims data) will ensure that the data are comparable across time and location. As noted for the DQIP initial measure set, articulating the collection process and environment exposes cultural or other barriers to data collection (or sharing), facilitates auditing, and improves the data’s external validity.

Clearly, one goal of adverse event systems is to allow aggregate reporting of events for purposes of both assessing known problems before and after interventions and detecting new problems. Attention to other requirements will allow appropriate comparisons of events. Standards such as Health Level Seven (HL7) (discussed in Chapter 4) and specifications such as extensible markup language (XML) may help improve data sharing but only if the contents of these shared items are based on the same terminology—for both items and responses. Ensuring that responses are easily combined is often beyond the realm of data standards but must be considered if large datasets will be generated. For example, different systems may allow a male to be represented as “Male,” “1,” “0,” or “M.” Integrating these terms will be a challenge.

Looking to the future, it is likely that spontaneous reporting will be important indefinitely, especially for near misses; however, use of automated triggers is likely to grow as more computerized information becomes avail-