Cystatin C in a composite risk score for mortality in patients with infective endocarditis: a cohort study

OBJECTIVE: To develop a multimarker prognostic score for infective endocarditis (IE). DESIGN: Retrospective case–control. SETTING: Secondary care. Single centre. PARTICIPANTS: 125 patients with definite IE. PRIMARY OUTCOME MEASURES: 90-day and 5-year mortality. RESULTS: Mean age was 62.7±17 years. The 90-day and 5-year mortality was 10.4% and 33.6%, respectively. CysC levels at admission and over 20% increases in CysC levels during 2 weeks of treatment were prognostic for 90-day and 5-year mortality independent of creatinine estimated glomerular filtration rate. In multivariate analyses, CysC (OR 5.42, 95% CI 1.90 to 15.5, p=0.002) and age (OR 1.06, 95% CI 1.02 to 1.10, p=0.002) remained prognostic for 5-year mortality. NT-proBNP, TnT, C reactive protein and interleukin 6 were also linked to prognosis. A composite risk scoring system using levels of CysC, NT-proBNP, age and presence of mitral valve insufficiency was able to separate a high-risk and a low-risk group. CONCLUSIONS: CysC levels at admission and increase in CysC after 2 weeks of treatment were independent prognostic markers for both 90-day and 5-year mortality in patients with IE. A multimarker composite risk scoring system including CysC identified a high-risk group.