Any discussion of patient safety usually begins with citations from the report of the Institute of Medicine (IOM) “ToErr is Human”¹ released in 1999. However, there were core articles that preceded To Err is Human which were used to form the basis of this landmark study. The paper by Classen et al² published in JAMA in 1991 is one of those articles. Classen and colleagues described how adverse drug events could be identified in an integrated hospital information system using a computer program to detect a variety of indicators of harm associated with adverse drug events.

At the time the article was written …