ASSESSING DIAGNOSTIC-CRITERIA FOR ACTIVE INFECTIVE ENDOCARDITIS

A study was performed to describe agreement among experts on their cla ssification of patients, in the absence of information concerning risk factors, as to the presence of infective endocarditis (IE). The study also assessed the clinical characteristics that enabled the experts t o determine that a patient had IE. All patients with a discharge diagn osis of IE were identified prospectively from 54 hospitals in the Dela ware Valley over a 3-year period. Patients were part of a case-control study of risk factors for IE. Three infectious disease experts indepe ndently reviewed abstracted hospital records and classified each of 15 1 eligible patients as a definite, probable or possible case, or a pro bable non-case, both based on clinical judgment and using a modified s tandard definition. Experts were more likely to classify a patient as a definite case of IE on the basis of clinical judgment than by using the modified standard definition. Agreement between reviewers was 92 t o 95% when they were distinguishing only probable non-cases from other s. Agreement between reviewers on specific categories was lower (40 to 58%). The number of positive blood cultures was a strong predictor of a patient's being classified as a case, as was the type of infecting organism. It is concluded that experts are willing to make a definitiv e diagnosis of IE on the basis of blood culture information alone. Fur ther supporting evidence, such as the presence of vegetation on an ech ocardiogram, is needed when blood culture results are ambiguous.