Case Definitions and Validation Studies Case Definitions

A series of diagnostic criteria have been developed by Pelletier and Petersdorf (1977), von Reyn (1981), and the Duke group (l994). The Pelletier and Petersdorf criteria required pathological confirmation of the diagnosis of IE and thus, were not very useful for prospective clinical diagnosis [24]. Von Reyn and colleagues improved the case definitions to make them more clinically relevant [25]. In 1994, investigators from Duke University modified the von Reyn criteria to include echocardiographic findings in the diagnosis of IE [13]. In addition, they expanded the category of predisposing heart conditions to include intravenous drug use.

(i) Pelletier and Petersdorf criteria (see Table 6.2): Their classification scheme consisted of three diagnostic categories: definite, probable, and possible. These diagnostic criteria were quite specific but were not very sensitive. Many patients with clinically suspected IE failed to meet diagnostic criteria.

(ii) von Reyn criteria (see Table 6.3): The von Reyn system was designed to make the diagnostic criteria more clinically applicable. The classification scheme consisted of four categories: definite, probable, possible, and rejected. Pathological confirmation of vegetations, or of an abscess, was still required to define a case as definite. Thus many cases were classified as probable or possible since many patients did not have pathological confirmation (i.e., by surgery or autopsy) of their disorder. Although the von Reyn criteria lacked prospective validation, the specificity of their classification system was superior to that of Pelletier and Petersdorf.

(iii) Duke criteria: Investigators at Duke University further refined the diagnostic criteria to make the case definitions more clinically applicable to patients suspected of having acute IE. This group has since published modifications of their original criteria after the validation studies (see below) were completed [26]. The new criteria include the addition of the presence of Coxiella burnetii as a major criterion and the elimination of echocardiographic minor criterion. Possible IE has been redefined to include one major plus one minor criterion or three minor criteria (see Table 6.4). In addition, the role for transesophageal echocardiog-raphy for the diagnosis of IE has been made more explicit to include patients with prosthetic valves and those suspected of having complicated IE (such as a paravalvular abscess) [26].

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