Antibiotic prophylaxis for patients at risk of infective endocarditis: an increasing evidence base?

Around 100 years ago, the first link between infective endocarditis (IE) and dental procedures was hypothesised; shortly after, physicians began to use antibiotics in an effort to reduce the risk of developing IE. Whether invasive dental procedures are linked to the development of IE, and antibiotic prophylaxis (AP) is effective, have since remained topics of controversy. This controversy, in large part, has been due to the lack of prospective randomised clinical trial data. From this suboptimal position, guideline committees representing different societies and countries have struggled to reach an optimal position on whether AP use is needed for invasive dental procedures (or other procedures) and in whom. We present the findings from an investigation involving a large US patient database, published earlier this year, by Thornhill and colleagues. The work featured the use of both a cohort and case-crossover design and demonstrated there was a significant temporal association between invasive dental procedures and development of IE in high-IE-risk patients. Furthermore, the study showed that AP use was associated with a reduced risk of IE. Additional data, also published this year, from a separate study using nationwide hospital admissions data from England by Thornhill's group, showed that certain dental and non-dental procedures were significantly associated with the subsequent development of IE. Two other investigations have reported similar concerns for non-dental invasive procedures and risk of IE. Collectively, the results of this work support a re-evaluation of the current position taken by the National Institute for Health and Care Excellence (NICE) and other organisations that are responsible for publishing practice guidelines.