Infective Endocarditis Increase Associated With Withdrawal of Antibiotic Prophylaxis: Presented at AHA

By Walter Alexander

CHICAGO -- November 20, 2014 -- Current United Kingdom practice recommendations suggest not providing antibiotic prophylaxis before invasive dental procedures, despite an associated rise in endocarditis cases, according to researchers at 2014 Annual Meeting of the American Heart Association (AHA). The National Institute for Health and Care Excellence (NICE) says it will, however, immediately review its guidance.

Invasive dental procedures can result in Viridans streptococci being released into the circulation, explained lead author Mark Dayer, MD, Taunton and Somerset National Health Service Trust, United Kingdom, speaking at a press conference here on November 19. “It is believed that infective endocarditis can develop as a consequence of this in susceptible individuals,” he added.

Since the first AHA guidelines on antibiotic prophylaxis were issued in 1955, guideline-recommended antibiotic doses have progressively become lower, with a shorter duration of administration and fewer patients indicated as being at risk.

“In March 2008,” Dr. Dayer noted, “NICE surprised the health community with their recommendation that, due to an absence of evidence, antibiotic prophylaxis should no longer be used in the United Kingdom.” The guideline specifically listed individuals undergoing dental procedures, and procedures in the gastrointestinal, genitourinary, and respiratory tracts as being exempted from prophylaxis.

To determine the impact of the guideline change, Dr. Dayer and colleagues reviewed all single-dose prescriptions for amoxicillin 3 g or clindamycin 600 mg between January 2004 and March 2013, and reviewed 19,804 cases in the United Kingdom with primary diagnoses of infective endocarditis in the same time period.

Dr. Dayer noted that, following the 2008 guideline, there was an exponential nearly 90% drop in prescriptions. By March 2013, he estimated, the number of infective endocarditis cases per month had risen by 25% more than expected (from 140 to 175 cases/month). Increases were in both the highest and lowest risk groups, but were nearly doubled in the latter. The change began just 3 months after the guideline introduction. A slight upward shift in death rates in the infective-endocarditis population since the guideline change, however, is not significant.
Dr. Dayer and colleagues did not, however, recommend a, practice change. “Although we have demonstrated a temporal association, we have not demonstrated a cause-effect relationship, and other explanations for the change are possible,” he stated.

The research team called for a prospective, randomised, controlled trial to determine whether or not the association is, in fact, causal.

AHA discussant Dhruv S. Kazi, MD, University of California San Francisco, San Francisco, California, commented: “As presented, these data are inadequate to alter the weight of evidence on which the prophylaxis guidelines are based, and should not prompt changes in prescribing practice at this time.”

The study has just been published by the Lancet:

[Presentation title: The Incidence of Infective Endocarditis in England is Increasing - An Assessment of the Impact of Cessation of Antibiotic Prophylaxis Using Population Statistics. Abstract LBCT03]

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