A pragmatic approach for mortality prediction after surgery in infective endocarditis: optimizing and refining EuroSCORE

[Objective] To simplify and optimize the ability of EuroSCORE I and II to predict early mortality after surgery for infective endocarditis (IE).
[Methods] Multicentre retrospective study (n = 775). Simplified scores, eliminating irrelevant variables, and new specific scores, adding specific IE variables, were created. The performance of the original, recalibrated and specific EuroSCOREs was assessed by Brier score, C-statistic and calibration plot in bootstrap samples. The Net Reclassification Index was quantified.
[Results] Recalibrated scores including age, previous cardiac surgery, critical preoperative state, New York Heart Association >I, and emergent surgery (EuroSCORE I and II); renal failure and pulmonary hypertension (EuroSCORE I); and urgent surgery (EuroSCORE II) performed better than the original EuroSCOREs (Brier original and recalibrated: EuroSCORE I: 0.1770 and 0.1667; EuroSCORE II: 0.2307 and 0.1680). Performance improved with the addition of fistula, staphylococci and mitral location (EuroSCORE I and II) (Brier specific: EuroSCORE I 0.1587, EuroSCORE II 0.1592). Discrimination improved in specific models (C-statistic original, recalibrated and specific: EuroSCORE I: 0.7340, 0.7471 and 0.7728; EuroSCORE II: 0.7442, 0.7423 and 0.7700). Calibration improved in both EuroSCORE I models (intercept 0.295, slope 0.829 (original); intercept –0.094, slope 0.888 (recalibrated); intercept –0.059, slope 0.925 (specific)) but only in specific EuroSCORE II model (intercept 2.554, slope 1.114 (original); intercept –0.260, slope 0.703 (recalibrated); intercept –0.053, slope 0.930 (specific)). Net Reclassification Index was 5.1% and 20.3% for the specific EuroSCORE I and II.
[Conclusions] The use of simplified EuroSCORE I and EuroSCORE II models in IE with the addition of specific variables may lead to simpler and more accurate models.
This work was supported by the Ministerio de Economía y Competitividad, Instituto de Salud Carlos III—co-financed by European Development Regional Fund A way to achieve Europe ERDF, Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015); Catalan Society of Cardiology (Grant Orion Pharma); and Spanish Society of Cardiology.