Prospective Validation of PREDICT and Its Impact on the Transesophageal Echocardiography Use in Management of Staphylococcus aureus Bacteremia

Abstract

Background: Infective endocarditis (IE) is the most feared complication of Staphylococcus aureus bacteremia (SAB). Transesophageal echocardiogram (TEE) is generally recommended for all patients with SAB; however, supporting data for this are limited. We previously developed a scoring system, "PREDICT," that quantifies the risk of IE and identifies patients who would most benefit most from undergoing TEE. The current prospective investigation aims to validate this score.

Methods: We prospectively screened all consecutive adults (≥18 years) hospitalized with SAB at 3 Mayo Clinic sites between January 2015 and March 2017.

Results: Of 220 patients screened, 199 with SAB met study criteria and were included in the investigation. Of them, 23 (11.6%) patients were diagnosed with definite IE within 12 weeks of initial presentation based on modified Duke's criteria. Using the previously derived PREDICT model, the day 1 score of ≥4 had a sensitivity of 30.4% and a specificity of 93.8%, whereas a day 5 score of ≤2 had a sensitivity and negative-predictive value of 100%. Additional factors including surgery or invasive procedure in the past 30 days, prosthetic heart valve, and higher number of positive blood culture bottles in the first set of cultures were associated with increased risk of IE independent of the day 5 risk score.

Conclusions: We validated the previously developed PREDICT scoring tools for stratifying risk of IE, and the need for undergoing a TEE, among cases of SAB. We also identified other factors with predictive potential, although larger prospective studies are needed to further evaluate possible enhancements to the current scoring system.

Keywords: Staphylococcus aureus; bacteremia; bloodstream infection; infective endocarditis; transesophageal echocardiography.

© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Figures

Figure 1.

PREDICT II scores, rates of infective endocarditis, and echocardiogram use in the study population. Abbreviations: IE, infective endocarditis; PREDICT, Predicting Risk of Endocarditis Using a Clinical Tool; TEE, transesophageal echocardiogram; TTE, transthoracic echocardiogram.

Figure 2.

Calibration of the day 1 prediction tool. The figure shows the calibration curves for predicting the risk of IE using the published day 1 scoring system. Predictions were generated from logistic regression in 2 ways, by modeling both of the constituent risk factors for the day 1 score (1) as 2 separate variables (“Model-Predicted” results in the left panel) and (2) as a single summary index (“Score-Predicted” results in the right panel). Calibration is judged by the Loess-estimated calibration curve (solid line) and its proximity to the reference line representing perfect calibration (dashed line). Shaded regions are 95% confidence limits; symbols depict observed proportions with IE for 5 equally sized subgroups. Abbreviations: CL, confidence limit; IE, infective endocarditis.

Figure 3.

Calibration of the day 5 prediction tool. The figure shows the calibration curves for predicting risk of IE using the published day 5 scoring system. Predictions were generated from logistic regression in 2 ways, by modeling all of the constituent risk factors for the day 5 score (1) as 3 separate variables (“Model-Predicted” results in the left panel) and (2) as a single summary index (“Score-Predicted” results in the right panel). Calibration is judged by the Loess-estimated calibration curve (solid line) and its proximity to the reference line representing perfect calibration (dashed line). Shaded regions are 95% confidence limits; symbols depict observed proportions with IE for 5 equally sized subgroups. Abbreviations: CL, confidence limit; IE, infective endocarditis.