Risk Factors of Endocarditis in Patients with Enterococcus faecalis Bacteremia: External Validation of the NOVA Score

BACKGROUND:  The NOVA score is a recently developed diagnostic tool to identify patients with increased risk of infective endocarditis (IE) among patients with Enterococcus faecalis (EF) bacteremia. We aim to validate an adapted version of the NOVA score and to identify risk factors for IE in patients with EF bacteremia.

METHODS:  From January 1, 2010 to December 31, 2013, we included 647 consecutive patients with EF bacteremia. Predictors of IE were identified with multivariable Cox regression. The NOVA score was used in a slightly adapted form; 2/2 positive blood cultures resulted in 5 points, unknown origin of infection 4 points, prior valve disease 2 points and heart murmur 1 point.

RESULTS:  IE was diagnosed in 78 patients (12%). Monomicrobial EF bacteremia (HR 3.60; CI95% 1.6-8.0), prosthetic heart valve (HR 6.2; CI95% 3.8-10.1), male sex (HR 2.0; CI95% 1.1-3.8), and community acquisition (HR 1.8; CI95% 1.1-2.9) were independently associated with IE. The adapted NOVA score was applied in the 240 patients examined by echocardiography. A low score (<4) was found in 40 patients (17%), implying a low likelihood of IE. Of the 78 patients with IE, 76 had a high score (≥4), resulting in a sensitivity of 97%, specificity of 23%, a negative predictive value of 95% and a positive predictive value of 38%.

CONCLUSION:  Monomicrobial EF bacteremia, community acquisition, prosthetic heart valve and male sex are associated with increased risk of IE. In our retrospective cohort, the adapted NOVA score performed well suggesting it could be useful in guiding clinical decisions.