A retrospective epidemiologic study to define risk factors, microbiology, and clinical outcomes of infective endocarditis in a large tertiary-care teaching hospital

OBJECTIVE: This study aims to define risk factors as well as their association with microbiology and clinical outcomes in a large US infective endocarditis population. METHODS: Hospital records were searched for appropriate infective endocarditis–related ICD codes from 16 July 2007 to 13 August 2015. A total of 363 cases were retrospectively identified that met definite Modified Duke Criteria for infective endocarditis and were analyzed by age group, causative organism, and associated risk factors for use of valvular surgical intervention, 30/90/180-day mortality after admission, and embolic phenomena. RESULTS: Chronic hemodialysis was the most common risk factor (26.7% of cases). Of all age groups, those aged 78+ years had the lowest 30-day mortality but those aged 58–77 years had the highest mortality (p = 0.039). Staphylococcus aureus was the most prevalent causative organism. Those aged 78–97 years were more likely to have enterococcal infective endocarditis than those aged 18–27 years (p = 0.0144). Chronic hemodialysis associated infective endocarditis was more likely to be caused by coagulase-negative staphylococcus (p = 0.0121) and have a higher 30-day mortality (p = 0.141) than intravenous drug use associated infective endocarditis. Intravenous drug use and chronic hemodialysis were similarly likely to be caused by S. aureus. Intravenous drug use associated infective endocarditis was more likely to be caused by viridans group streptococci (p = 0.0001). Fungal infective endocarditis was most likely to embolize. Chronic hemodialysis patients were less likely to undergo valvular surgery (p = 0.001) and those with chronic hemodialysis who did had lower mortality than those only managed medically that did not reach statistical significance (p = 0.2991). Infective endocarditis caused by coagulase-negative staphylococci had the greatest 30-day mortality at 31.3% but did not reach statistical significance over all other causative organisms (p = 0.060). CONCLUSION: In our infective endocarditis population, S. aureus is the predominant causative organism. Chronic hemodialysis is the most common risk factor present in infective endocarditis populations and has greater association with coagulase-negative staphylococci and 30-day mortality. Intravenous drug use had the lowest mortality among risk factors with a similar proportion of S. aureus infective endocarditis compared to chronic hemodialysis but a higher proportion of viridans group streptococci infective endocarditis cases. Further study will need to be performed on prevention and treatment of infective endocarditis in chronic hemodialysis patients.