title: External validation of a clinical decision rule: we need events in a population in order to rule them out!
abstract: We respond to the Lorton et al. article on external validation of the PECARN study. With an event rate of only 0.6%, we believe that their study failed to confirm the safety of this rule. Such a low number of events should call for caution when interpreting the results of diagnostic tests.
authors.affiliation: Emergency Department, hôpital Pitié-Salpêtrière, Paris, France. yonathanfreund@gmail.com.|Paris Sorbonne Université, Univ-Paris06, Paris, France. yonathanfreund@gmail.com.
authors.forename: Yonathan
authors.initials: Y
authors.lastname: Freund
authors.affiliation: Emergency Department, hôpital Pitié-Salpêtrière, Paris, France.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Philippon
mesh_terms: D006259:Craniocerebral Trauma; D020000:Decision Support Systems, Clinical; D006801:Humans