Baseline C-reactive protein levels and prognosis in patients with infective endocarditis: A prospective cohort study

Abstract

Background: Early diagnosis and risk-stratification among infective endocarditis (IE) patients are limited by poor microbiological yield and inadequate characterization of vegetations. A simple tool that can predict adverse outcomes in the early phase of management is required.

Aim: To study the prognostic value of C-reactive protein (CRP) levels at admission and its role in predicting various clinical outcomes.

Methods: In a prospective study of consecutive IE patients diagnosed by modified Duke's criteria, we measured the peak levels of CRP and erythrocyte sedimentation rate (ESR) in the first 3 days of admission and correlated it with in-hospital mortality, six-month mortality, embolic phenomena and the need for urgent surgery. Predefined laboratory-microbiological sampling protocols and antibiotic-initiation protocols were followed. Receiver-operating-characteristics curves were generated to identify a reliable cut-off for CRP in predicting various outcomes.

Results: Out of 101 patients who were treated, 85 patients had 'definite' IE. Blood cultures were positive in 55% (n = 39); and Staphylococcus species was the most common organism. Major complications occurred in 74.1% (n = 63) and in-hospital mortality was 32.9% (n = 28). Mean ESR and CRP levels were 102 ± 31 mm/h and 51 ± 20 mg/l, respectively. In multivariable analysis, high CRP levels were independently predictive of mortality, major complications, embolic events and need for urgent surgery. A CRP >40 mg/l predicted adverse outcomes with a sensitivity of 73% and specificity of 99%.

Conclusion: The study shows that baseline CRP level in the first 3 days of admission is a strong predictor of short term adverse outcomes in IE patients, and a useful marker for early risk stratification.

Keywords: Biomarker; C-reactive protein; Infective endocarditis; Prognostication; Valvular heart disease.

Fig. 1

Flowchart depicting recruitment of infective endocarditis patients prospectively.

Fig. 2

Receiver operating characteristics curve generated for C-reactive protein against the composite of major complications among 85 patients with IE.

Fig. 3

Kaplan-Meier survival curve analysis showing C-reactive protein >40 mg/l and hemoglobin <10 g/dl as predictors for six-month mortality.