Effect of conjugated bilirubin on clinical outcomes in infective endocarditis

Liver dysfunction is associated with adverse events in infective endocarditis (IE). However, few studies have explored the predictive value of conjugated bilirubin (CB) in IE. We aimed to investigate the nature of the link between CB and adverse prognosis in patients with IE. Consecutive patients with IE between January 2009 and July 2015 were enrolled. Multivariate analysis was performed to confirm whether CB was an independent risk factor for adverse outcomes. In all, 1010 patients were included and divided into two groups according to admission CB level (μmol/L): normal (≤ 7.0, n = 820) and elevated (> 7.0, n = 190) CB groups. In-hospital mortality (5.0% vs. 22.1%, p < 0.001) and major adverse cardiac events (16.8% vs. 36.3%, p < 0.001) were significantly higher in patients with increased CB. A possible J-shaped relationship was found between CB and in-hospital events. Further, CB had more predictive power than total bilirubin in predicting in-hospital death (AUC 0.715 vs. 0.674, p = 0.010). Elevated CB was an independent predictor of in-hospital death (adjusted OR = 2.62, 95%CI 1.40–4.91, p = 0.003). Moreover, CB (increment 1 μmol/L) was independently associated with higher long-term mortality. Kaplan–Meier curves indicated that patients with elevated CB were associated with higher cumulative rate of long-term death (log-rank = 21.47, p < 0.001). CB, a biomarker of liver function, was a relatively powerful predictor of in-hospital and long-term adverse prognosis of IE and could likely comprise a novel risk evaluation strategy.