Dental and cardiac risk factors for infective endocarditis. A population-based, case-control study.

BACKGROUND: Although antibiotic prophylaxis against infective endocarditis is recommended, the true risk factors for infective endocarditis are unclear.

OBJECTIVE: To quantitate the risk for endocarditis from dental treatment and cardiac abnormalities.

DESIGN: Population-based, case-control study.

SETTING: 54 hospitals in the Philadelphia area.

PATIENTS: Persons with community-acquired infective endocarditis not associated with intravenous drug use were compared with community residents, matched by age, sex, and neighborhood of residence.

MEASUREMENTS: Information on demographic characteristics, host risk factors, and dental treatment was obtained from structured telephone interviews, dental records, and medical records.

RESULTS: During the preceding 3 months, dental treatment was no more frequent among case-patients than controls (adjusted odds ratio, 0.8 [95% CI, 0.4 to 1.5]). Of 273 case-patients, 104 (38%) knew of previous cardiac lesions compared with 17 controls (6%) (adjusted odds ratio, 16.7 [CI, 7.4 to 37.4]). Case-patients more often had a history of mitral valve prolapse (adjusted odds ratio, 19.4 [CI, 6.4 to 58.4]), congenital heart disease (adjusted odds ratio, 6.7 [CI, 2.3 to 19.4]), cardiac valvular surgery (adjusted odds ratio, 74.6 [CI, 12.5 to 447]), rheumatic fever (adjusted odds ratio, 13.4 [CI, 4.5 to 39.5]), and heart murmur without other known cardiac abnormalities (adjusted odds ratio, 4.2 [CI, 2.0 to 8.9]). Among case-patients with known cardiac lesions--the target of prophylaxis--dental therapy was significantly (P = 0.03) less common than among controls (adjusted odds ratio, 0.2 [CI, 0.04 to 0.7] over 3 months). Few participants received prophylactic antibiotics.

CONCLUSIONS: Dental treatment does not seem to be a risk factor for infective endocarditis, even in patients with valvular abnormalities, but cardiac valvular abnormalities are strong risk factors. Few cases of infective endocarditis would be preventable with antibiotic prophylaxis, even with 100% effectiveness assumed. Current policies for prophylaxis should be reconsidered.