Reply to Thornhill et al

To the editor—We do not agree that the conclusions we present in our article are too strongly worded [1]. The main conclusion is that, “The results suggest that the current Swedish recommendation not to administer antibiotic prophylaxis for the prevention of IE [infective endocarditis] in dentistry has not led to an increased incidence of oral streptococcal IE among high-risk individuals.” The second statement, “AP [antibiotic prophylaxis] in dentistry for the prevention of IE may be discontinued,” is taken out of context. The sentence in its entirety reads, “This study adds to the existing evidence indicating that AP in dentistry for the prevention of IE may be discontinued.”

The studies referred to (and produced) by Thornhill et al [2] have been criticized for using a methodology that creates inflated estimates and for lacking data on microbiology [3, 4]. Instead, the latest study from the United Kingdom adds to the growing body of evidence that suggests that AP may be discontinued, by indicating no effect of guidance on IE trend in the United Kingdom at 9 years follow-up, despite an 88% drop in AP prescriptions by dentists [4].

Regarding the study that indicates an excess 35 cases per month of IE in the United Kingdom 5 years after the guideline change [5], the statistical editor for the Cochrane Effective Practice and Organisation of Care concluded that the methodology was at high risk of bias [3]. A reanalysis of the same data showed no effect on IE trend [3].

In the study by Thornhill et al in 2022, once again, microbiological data are missing, and the methodology may cause inflated estimates [3]. The distinction between IE and viridans group streptococcal IE (VGS-IE) is important because 73% of IE cases are caused by microorganisms not commonly attributed to dental procedures [4].

Our current study provides a 5-year follow-up of VGS-IE cases that could theoretically be associated with dental procedures. We are confident that we identified virtually all high-risk individuals from 1964 living in Sweden from 2008 to 2018. In our article, we note that although our results seem reassuring for Swedish policy makers, any extrapolation of the results depends on the assumption that Swedish dentists have adhered to the recommendation not to prescribe AP to high-risk individuals. It is problematic to compare the fall of AP in England and Sweden in the way that Thornhill et al do. They write that “dentists more frequently prescribe amoxicillin to treat dentoalveolar and other orofacial infections than for AP purposes.” This may be the case in England, but Swedish dentists have no such tradition because penicillin V is the first choice to treat these infections, sometimes combined with metronidazole. We also recognize that there are remaining indications for AP other than prevention of IE. AP is commonly used during dental implant placement, a procedure that is more frequent than invasive dental procedures among high-risk individuals (>30 000 vs >10 000 procedures/year, respectively). Because of this, if Swedish dentists adhere to the changed recommendation as diligently as UK dentists, we do not expect as dramatic a fall in amoxicillin prescriptions as seen in England.

Notes

Disclaimer. The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, and approval of the manuscript; and decision to submit the manuscript for publication.

Financial support. The work was supported by funding from the Board of Doctoral Education at the Karolinska Institutet, the Public Health Agency of Sweden (reported by B. L.), Folktandvården Stockholm AB, Steering Group for Collaborative Odontological Research at Karolinska Institutet and Stockholm City County (reported by B. L.), and the Swedish Dental Association.