PREVENTION OF INFECTIVE ENDOCARDITIS: EFFECTIVENESS OF PROPHYLAXIS
Research in animal models has consistently shown that the administration of antibiotics before (or occasionally shortly after) an induced bacteremia can prevent IE on damaged heart valves. However, proof that this approach is effective in humans is lacking. One major problem with the available literature is that multiple studies repeatedly demonstrate that few high-risk patients take antibiotic prophylaxis. In the largest retrospective case-control studies to date, less than 25% of high-risk patients (based on preexisting structural heart disease) actually took antibiotic prophylaxis before a procedure for which it was indicated. This has led to very small groups of patients in whom an analysis of efficacy can be performed.- A large population-based case-control study of patients with IE in the Philadelphia metropolitan area failed to show that dental treatment was a risk factor for IE, thereby calling into question the role of prophylactic antibiotics before such treatments. Patients who took antibiotic prophylaxis were not protected against development of IE, but the number of patients who took prophylaxis was very small, making it difficult to draw a conclusion from this study alone.- One small (eight cases) case-control study from the Cleveland Clinic showed efficacy of antibiotic prophylaxis but was notable for questionable assignment of causality to distant dental procedures.- A Dutch national case-control study failed to show significant efficacy of antibiotic prophylaxis prior to medical or dental procedures.- A French case-control study concluded that procedures increase the risk of endocarditis but failed to show protective efficacy of antibiotic prophylaxis.To date, the available literature does not suggest a protective benefit of antibiotic prophylaxis. However, these studies have been underpowered to detect a protective effect as large as 20% or greater.*49/348/5*
