PROCEDURES AT RISK FOR INFECTIVE ENDOCARDITIS - A CASE-CONTROL STUDY

To evaluate the procedure-related relative risk (RR) of bacterial endocarditis and the protective efficacy of antibiotic prophylaxis for prevention of bacterial endocarditis, we conducted a case-control study in three french regions (Ile de France, Rhone-Alpes, Lorraine). Cases (n = 171) met the Von Reyn's diagnostic criteria and originated from the nationwide endocarditis study carried out in France from November 1990 to October 1991. Controls were selected in each region from inpatients of cardiology and medicine departments of the regional university hospital. Cases and controls were matched for sex, age (same 5-year-age category) and underlying cardiac disease (distributed in 3 classes : no known cardiac disease, abnormal native valve and prosthetic valve). 88 cases vs 70 controls had had at least one procedure within 3 months before case hospitalization or control questioning (RR - 1.6, CI 95 % = 1.01-2.53). Among dental procedures, only root canal therapy and scaling, but not extraction, were linked to a significantly increased RR (3 and 2.5 respectively). Likewise, among other procedures, only surgical operations had a significantly increased RR (4.7). The percentage of cases attributable to these procedures was estimated to be lower than 20 %. Cases significantly more frequently than controls had had an infectious episode or a skin wound during the past three month period. We failed to demonstrate that antibiotic prophylaxis had a significant protective efficacy for prevention of bacterial endocarditis. Nevertheless this should be analyzed cautiously : a lack of power and the diffusion of antibiotic prophylaxis recommendations might partly explain these negative results.