Procedures associated with infective endocarditis in adults - A case control study

Object: To assess the relative risk of infective endocarditis associated with various procedures and the protective efficacy of antibiotic prophylaxis by a case-control study. Background: Recommendations for the prevention of infective endocarditis are based on the hypothesis of a relationship between procedures and infective endocarditis which is supported by anecdotal reports and data from experimental models. Methods: Cases met the Von Reyn's diagnostic criteria modified with echocardiographic and macroscopic findings. Controls were recruited from cardiology or medicinal wards. Cases (n = 171) and controls were matched as regards sex, age and underlying cardiac condition. They were requested to indicate all the medical, surgical or dental procedures within the previous 3 months. Among potential confounding factors, infectious episodes and skin wounds in the previous 3 months were reported. Antibiotic prophylaxis administration was documented for type, dosage, duration and administration schedule. Results: Cases significantly more frequently than controls had undergone at least one procedure (matched odds ratio, 1.6, 95% confidence interval, 1.01 to 2.53). Dental procedures considered as a whole were not associated with an increased risk, although scaling and root canal treatment showed a trend towards a higher risk of infective endocarditis (P = 0.065). Among non-dental procedures, only surgery appeared to be at risk (matched odds ratio, 4.7, 95% confidence interval, 1.02 to 22). Considering all procedures, the risk of infective endocarditis increased significantly with the number of procedures. While general co-morbid conditions did not differ between the two groups, cases significantly more frequently than controls had experienced an infectious episode or a skin wound. In multivariate analysis, only infectious episodes and skin wounds significantly increased the risk of infective endocarditis. Scaling was the only independent risk factor for viridans streptococcal infective endocarditis. The 46% protective efficacy of antibiotic prophylaxis was not significant. Conclusions: Procedures do increase the risk of infective endocarditis. The interpretation of the apparent low risk associated with dental procedures may be as a result of the current practice of antibiotic prophylaxis. Our data suggest that surgery should be more clearly mentioned in future guidelines, and reemphasize that a rigorous treatment of any focal infection in cardiac patients is mandatory. From the efficacy rate of antibiotic prophylaxis, it can be estimated that the overall incidence of infective endocarditis might be reduced by 5 to 10% in France by appropriate use of antibiotic prophylaxis in cardiac patients.