A high-sensitivity method for identifying a rare subpopulation of patients with infective endocarditis for a prospective case-control study.

Background: Infective endocarditis (IE) is an uncommon disease, but it is associated with high morbidity and mortality. The low incidence and varied clinical presentation make identification of these patients recently admitted to hospitals particularly challenging. The authors designed a prospective electronic health record screening tool (PEHRST) to identify inpatients with IE for a prospective case-control study designed to determine levels of association between oral hygiene and periodontal disease indexes and IE. Methods: The authors used PEHRST to identify, soon after admission, patients hospitalized with IE based on the presence of any 2 of the 4 screening criteria: orders for blood culture or echocardiography and completed consultations from infectious diseases or cardiovascular medicine. They determined the utility of this tool by comparing the prospectively generated PEHRST list of potential inpatients with IE with a retrospective list of inpatients with IE discharged during the same 2-year period. Results: Of the 74,345 patients admitted during the study period, PEHRST identified 11,944 (16%) with at least 2 of the 4 screening criteria. Retrospective claims data showed that 198 patients were discharged during this time period with an IE diagnosis, all of whom had been identified by PEHRST (sensitivity = 100%; 95% CI, 98.2% to 100%; specificity = 84%; 95% CI, 83.9% to 84.4%). An analysis of the timing of the 4 screening criteria indicated that the median days were all within 24 hours of admission. Conclusions: PEHRST made possible the identification of rare patients with IE soon after hospital admission with high sensitivity, allowing the parent study to achieve sufficient enrollment of cases for the primary outcome measure.