Background — In 2007, the American Heart Association recommended antibiotic prophylaxis for the prevention of infective endocarditis (IE) for only the highest-risk patients. Whether this change affected the use of antibiotic prophylaxis and the incidence of IE is unclear.
Methods — IE-related hospitalizations were identified from 2002 to 2014 among all adults and those at high and moderate risk for IE, stratified by age. Prescriptions for antibiotic prophylaxis were obtained from the Ontario Drug Benefit database for adults ≥65 years of age. Outcomes were antibiotic prophylaxis prescription rates and incidence of IE-related hospitalization. Trends in patient and pathogen characteristics were analyzed. Time series analyses were performed with segmented regression and change-point analyses.
Results — Prescriptions for antibiotic prophylaxis decreased substantially in the moderate-risk cohort after the guideline revision (mean quarterly prescriptions, 30 680 versus 17 954 [level change, −6,481; P=0.0004] per 1 million population) with a minimal, yet significant, decrease followed by a slow increase in the high-risk group. There were 7551 IE-related hospitalizations among 6884 adults ≥18 years of age. Among adults ≥65 years of age, the mean IE rate increased from 872 to 1385 and 229 to 283 per 1 million population at risk per quarter in the high- and moderate-risk groups, respectively. Change-point analyses indicated that this increase occurred in the second half of 2010 in adults ≥65 years of age, 3 years after the American Heart Association guideline revision. Staphylococcus aureus and streptococcal species accounted for 30.3% and 26.4% of all IE, with a decrease in streptococcal infections over time.
Conclusions — Antibiotic prophylaxis decreased significantly in the moderate-risk group with minimal change in the high-risk group after the American Heart Association guideline revision in 2007. However, IE-related hospitalizations increased among both high- and moderate-risk patients 3 years after the revision. Our study provides support for the cessation of antibiotic prophylaxis in the moderate-risk population.
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