A new analysis of antibiotics prescribed before dental procedures has found that 80.9% are unnecessary, with most prescriptions being written for patients who don't require them.

The study, published today in JAMA Network Open, found that antibiotic prophylaxis was prescribed in more than 168,000 dental visits from 2011 to 2015. In 90% of these visits, a procedure was performed that would require antibiotic prophylaxis only for cardiac patients considered at high risk for secondary infections.

But according to guidelines from the American Heart Association (AHA) and the American Dental Association (ADA), fewer than one fifth of those prescriptions were needed, as the patient did not have a heart condition placing him or her at the highest risk of an adverse outcome from infective endocarditis, an infection of the inner lining of the heart.

The lead author of the study says the results indicate that dentists, who are responsible for roughly 10% of all antibiotic prescriptions, need to be included in antibiotic stewardship efforts.

"I think of dentists as being part of my primary care," Katie Suda, PharmD, a professor at the University of Illinois at Chicago (UIC) College of Pharmacy, told CIDRAP News. "They need to be included in this conversation around antibiotic use and prescribing and antibiotic stewardship."

Antibiotic recommendations have changed

Using data from a large national health claims database, Suda and her colleagues looked at all adult visits to a dentist from 2011 to 2015 and identified patients with an antibiotic prescription with a supply of 2 days or less that occurred within 7 days before the dental visit.

They then reviewed guidelines to determine whether the dental procedures are considered appropriate procedures for antibiotic prophylaxis. Procedures for which prophylaxis is recommended involve manipulation of gingival tissue or the periapical region of teeth, such as a tooth extraction.

They also looked to see which patients had an appropriate diagnosis for antibiotic prophylaxis. Under the 2007 AHA guidelines, one dose of antibiotics before dental visits is recommended for patients with cardiac conditions that are associated with a high risk of adverse outcomes from endocarditis. If patients didn't have such cardiac conditions, the prescription was considered inappropriate.

Previous guidelines from the ADA and the American Academy of Orthopaedic Surgeons had also recommended antibiotic prophylaxis before dental procedures for certain patients with prosthetic joints. But that recommendation was removed when the guidelines were revised in 2013.

"There have been guideline changes in the last 10 years that have narrowed the indications for antibiotics to prevent distant site infections…so we wanted to see if these guidelines were being followed," Suda said.

Of the more than 3 million dental visits with antibiotic prescriptions identified during the study period, 168,420 visits by 91,438 patients were considered eligible for the analysis. Most of the dental visits were classified as diagnostic (70.2%) and preventive (58.8%), and 90.7% involved gingival manipulation. Analysis of the patients found that 42.5% had prosthetic devices, and 20.9% had cardiac conditions associated with the highest risk of adverse outcomes from endocarditis. Per guidelines, only 19.1% of the antibiotic prescriptions were appropriate.

Suda said she wasn't entirely surprised by these results, given that studies in other countries have found 58% to 81% of dental antibiotic prescribing to be inconsistent with guidelines. Moreover, she cited the fact that 30% of outpatient prescribing in the United States has been found to be inappropriate.

"Unfortunately, this is consistent with what we see with other medical providers as well as dentists in other countries," she said.

Among the patients more likely to be prescribed antibiotics unnecessarily were women (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.17 to 1.25) and patients in the western United States (OR, 1.15; 95% CI, 1.06 to 1.25). But the patients most likely to receive unnecessary antibiotics were those with prosthetic joint devices (OR, 2.31; 95% CI, 2.22 to 2.41).

"That would be an area for us to target in the future to decrease unnecessary prescribing of antibiotic prophylaxis," Suda said.

While the most frequently prescribed antibiotic was amoxicillin (69.4%), clindamycin was the second most frequently prescribed antibiotic (16%). And in a multivariable analysis, Suda and her colleagues found that clindamycin was more likely to be unnecessarily prescribed compared to amoxicillin (OR, 1.10; 95% [CI], 1.05 to 1.15).

This is significant because clindamycin is associated with the highest risk of Clostridioides difficile infection, and dentists are the highest prescribers of clindamycin. A 2017 study conducted in Minnesota found that 15% of patients diagnosed as having community-associated C difficile infection had been prescribed an antibiotic by a dentist, and at least half of those prescriptions were for clindamycin.

Stewardship for dentists

Suda said that she and her colleagues are conducting interviews with dentists to figure out what's behind some of the inappropriate prescribing, and won't have more definitive answers until that research is done. But she has some initial thoughts about what's going on.

One theory that has come up is that while all medical providers face some pressure from patients to prescribe antibiotics, dentists are unique in that they may also receive pressure to prescribe from other clinicians.

"What we hear anecdotally is that orthopedic surgeons are pressuring dentists to prescribe antibiotics for those patients with prosthetic joints, even though the guidelines no longer recommend that," she said.

On a positive note, Suda noted that the analysis found that unnecessary antibiotic prescribing decreased over the study period, from 84.5% to 78.8% overall and across all geographic regions. That could indicate that the updated guidelines are starting to be implemented in patient care.

Suda and her colleagues recently conducted a small quality control project in which they implemented an antibiotic stewardship intervention at a UIC dental clinic based on the Centers for Disease Control and Prevention's core elements of hospital antibiotic stewardship programs. An analysis of that project found a decrease in antibiotic prescribing associated with the intervention, and dentists in the practice reported being more conscious of appropriate prescribing.

Those findings, published in February, give Suda some hope that the type of stewardship strategies that are working in other areas of medicine can be applied to dental practices.

"There has been some success with medical providers, especially pediatricians, in decreasing antibiotic prescribing, and perhaps some of those strategies can work for dentists," she said

See also:

May 31 JAMA Network Open study

Feb 13 CIDRAP News scan on dental stewardship study