Curbs on Predental Antibiotic Prophylaxis Maybe Went Too Far in Practice

November 09, 2018

CHICAGO — The 2007 advent of guidelines recommending against antibiotic prophylaxis (AP) before dental procedures in most patients might have had more of an impact than intended, a new analysis suggests.

It led to a sharp decline in AP for patients at all levels of risk for endocarditis, including those at highest risk, the one group for which the guidelines still recommended prophylaxis. And among that highest-risk group, reduced AP was followed by a significant 177% jump in endocarditis cases in the ensuing 8 years.

The analysis can't prove cause and effect, however.

The fall in AP prescribing in high-risk patients "is rather concerning and suggests some difficulty on the part of dentists in distinguishing between those at high risk, who are recommended to receive antibiotic prophylaxis, and those at moderate risk, who are not," said Martin H. Thornhill, MBBS, BDS, PhD, School of Clinical Dentistry, University of Sheffield, United Kingdom.

"Clear guidance and improved education and training of dentists might help improve this," Thornhill told | Medscape Cardiology in an email.

"However, dentists are not cardiologists, and so better communication between a patient's cardiologist, who is best placed to identify if they are at high risk or not, and the patient's dentist is likely to be the most effective way of ensuring all those who are recommended for prophylaxis receive it."

Thornhill is scheduled to presented the analysis based on 2003 to 2015 Medicare, Medicaid, and commercial insurance data on November 11 here at the American Heart Association (AHA) Scientific Sessions 2018. It was published online November 5 in the Journal of the American College of Cardiology.

The influential 2007 AHA-sponsored guidelines recommended AP be restricted to those at high risk for infective endocarditis (IE) who were undergoing invasive dental procedures, as reported by | Medscape Cardiology at the time. Such procedures consisted of those "that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa."

High-risk patients included those with previous IE, prosthetic valves, unrepaired cyanotic congenital heart defects, or congenital defects completely repaired with prosthetic material or a device by means of surgery or a transcatheter.

Similar guidelines were published by the European Society of Cardiology (ESC) in 2009, and the UK National Institute for Health and Care Excellence (NICE) announced stricter AP-curbing recommendations in 2008. Interestingly, increases in endocarditis cases were seen in the UK after the NICE guidelines came out.

The current analysis "strongly supports the current AHA antibiotic prophylaxis recommendations," Thornhill said. "Doctors and dentists should continue to put these into effect in their clinical practice, perhaps with some reassurance now about the benefit of giving antibiotic prophylaxis to those at high risk."

His group's estimates showed a significant 64% drop in AP prescriptions after 2007 for patients at moderate risk, and a "barely significant" 75% climb in their cases of IE after the AHA guidelines were introduced.

"This suggests that antibiotic prophylaxis prescribing may have a small degree of efficacy in those at moderate risk, but it is much less than in those at high risk," Thornhill said.

"This lower efficacy may be insufficient to warrant the use of antibiotic prophylaxis in those at moderate risk, given the potential problems of antibiotic prophylaxis that include the risk of adverse reactions and the risk of encouraging the development of antibiotic-resistant bacteria."

Another interpretation of the findings in the moderate-risk group, he said, is that perhaps they include people "with a number of different predisposing cardiac conditions. It is possible, therefore, that individuals with certain moderate-risk conditions might benefit more from antibiotic prophylaxis than others." That idea, however, would have to be tested in further studies, he said.

Among patients at lowest risk for IE, AP use was cut by half in the guidelines years, without any associated increase in IE cases, suggested the analysis, which was based on almost 200 million person-years of information on antibiotic prescribing, hospitalizations, and other care delivery.

Trends* in Antibiotic Prophylaxis (AP) and Infective Endocarditis (IE) Cases After vs Before 2007 AHA Guidelines
Parameter Low IE Risk Moderate IE Risk High IE Risk
AP prescribing 0.48 (0.42-0.54) 0.36 (0.32-0.41) 0.80 (0.68-0.96)
IE incidence 1.12 (0.71-1.76) 1.75 (1.03-3.0) 2.77 (1.66-4.61)
*Estimates of proportional changes (95% confidence interval) before to after introduction of the 2007 guidelines, 2003–2015.

Total reimbursed costs for inpatient care for IE rose throughout the entire study period, the report notes, despite a reduction in IE incidence.

This was in part because "the cost of treating infective endocarditis more than doubled between 2000 and 2015," Thornhill said, from a mean of about $44,000 to more than $92,000 by the end of the study period.

Meanwhile, "the cost of a prescription of antibiotic prophylaxis has more than halved, to just $2. The effect of this is to substantially increase the cost-effectiveness of antibiotic prophylaxis," he said.

"Taken at face value, these results suggest that this failure to comply with the AP guidelines may have contributed to potentially avoidable cases of endocarditis in the patients most at risk," says an accompanying editorial from Ann F. Bolger, MD, San Francisco General Hospital.

If it could be shown that the broad decrease in AP prescribing directly caused the rise in IE cases among high-risk patients, "these results would strike both fear and hope into the hearts of dedicated IE worriers — fear that some patients at high risk have been inadequately protected from IE due to lack of compliance with AP recommendations, and hope that there might finally be some indication that AP is actually effective in avoiding some cases of endocarditis."

However, "without knowing how many of the IE cases were in fact caused by organisms targeted by the recommended timing and type of prophylactic antibiotics, it is not possible to interpret these data in a way that supports causality."

Thornhill discloses receiving support from the Delta Dental Research and Data Institute for the current study. Disclosures for the other authors are in the report. Bolger did not include a disclosure statement.

American Heart Association (AHA) Scientific Sessions 2018: Abstract Su1136 / 1136. To be presented November 11, 2018.

J Am Coll Cardiol. Published online November 5, 2018. Article. Editorial

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