Antibiotics for the prevention of bacterial endocarditis (severe infection or inflammation of the lining of the heart chambers) in dentistry

Review question

This review, carried out by authors of the Cochrane Oral Health Group, has been produced to determine whether people at increased risk of bacterial endocarditis, a severe infection or inflammation of the lining of the heart chambers, should routinely take antibiotics before invasive dental procedures in order to reduce the incidence of endocarditis, the number of deaths, and the amount of serious illness this group of people experiences.

Background

Bacterial endocarditis (BE) is a rare disease, it is generally accepted that 10 out of 100,000 people will suffer from it each year. The infection often occurs on previously damaged or malformed areas of the heart. It is usually treated with antibiotics, however BE is a life-threatening condition and up to 30% of people who suffer from it die, even with antibiotic treatment.

It is thought that invasive dental procedures may cause BE in people who are at risk of developing it. It is not known how many cases of BE (if any) are directly caused this way. Many dental procedures cause bacteraemia, which is the presence of bacteria in the blood, and although it is usually dealt with quickly by the body’s immune system, it has been believed that bacteraemia may lead to BE in a few at risk people. Guidelines in many countries have recommended that before undergoing invasive dental procedures, people at high risk of BE should be given antibiotics in order to reduce the possibility of BE occurring. However, recent guidance by the National Institute for Health and Care Excellence (NICE) in England and Wales has recommended that antibiotics are not required for any interventional procedure, either dental or surgical.

Some authorities have questioned the routine use of antibiotics, arguing that overprescription has resulted in the emergence of resistance of many organisms to common antibiotics, and also that the occasional adverse effects of antibiotics (severe allergic reactions) may outweigh the potential benefits.

Study characteristics

The evidence on which this review is based was up to date as of January 2013.

The objective was to determine whether preventive (prophylactic) use of antibiotics, compared to no antibiotics or placebo, before invasive dental procedures in people at risk or at high risk of bacterial endocarditis influences the numbers of deaths, serious illness or incidence of endocarditis.

One study was included in this review, which compared the treatment of people at high risk of endocarditis who did develop BE and a group of people at high risk of endocarditis who did not develop BE. The study was an observational case-control study based in the Netherlands which looked at information about 349 people who contracted BE over a specific two year period. These people were matched to a similar group of people who had not contracted BE. All those participating in the study had undergone an invasive medical or dental procedure. The two groups were compared with regard to who had received preventive antibiotics before these procedures and those who did not.

Key results

It is unclear whether taking antibiotics as a preventive measure before undergoing invasive dental procedures is effective or ineffective against bacterial endocarditis in people at risk.

No studies were located that assessed numbers of deaths, serious adverse events requiring hospital admission, other adverse events, or cost implications of treatment.

There is a lack of evidence to support previously published guidelines in this area. It is not clear whether the potential harms and costs of antibiotic administration outweigh any beneficial effect. Ethically, practitioners need to discuss the potential benefits and harms of preventive antibiotic treatment with their patients before a decision is made about prescribing it.

Quality of the evidence

Although external factors relating to the study, such as inclusion of relevant participants and well defined parameters, were good, overall the observational and retrospective nature of the design of the study conferred a substantial risk of bias.

Authors' conclusions: 

There remains no evidence about whether antibiotic prophylaxis is effective or ineffective against bacterial endocarditis in people at risk who are about to undergo an invasive dental procedure. It is not clear whether the potential harms and costs of antibiotic administration outweigh any beneficial effect. Ethically, practitioners need to discuss the potential benefits and harms of antibiotic prophylaxis with their patients before a decision is made about administration.

Read the full abstract...
Background: 

Infective endocarditis is a severe infection arising in the lining of the chambers of the heart with a high mortality rate.

Many dental procedures cause bacteraemia and it was believed that this may lead to bacterial endocarditis (BE) in a few people. Guidelines in many countries have recommended that prior to invasive dental procedures antibiotics are administered to people at high risk of endocarditis. However, recent guidance by the National Institute for Health and Care Excellence (NICE) in England and Wales has recommended that antibiotics are not required.

Objectives: 

To determine whether prophylactic antibiotic administration, compared to no such administration or placebo, before invasive dental procedures in people at risk or at high risk of bacterial endocarditis influences mortality, serious illness or the incidence of endocarditis.

Search strategy: 

The following electronic databases were searched: the Cochrane Oral Health Group's Trials Register (to 21 January 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 12), MEDLINE via OVID (1946 to 21 January 2013) and EMBASE via OVID (1980 to 21 January 2013). We searched for ongoing trials in the US National Institutes of Health Trials Register (http://clinicaltrials.gov) and the metaRegister of Controlled Trials (http://www.controlled-trials.com/mrct/). No restrictions were placed on the language or date of publication when searching the electronic databases.

Selection criteria: 

Due to the low incidence of BE it was anticipated that few if any trials would be located. For this reason, cohort and case-control studies were included where suitably matched control or comparison groups had been studied. The intervention was the administration of antibiotic, compared to no such administration, before a dental procedure in people with an increased risk of BE. Cohort studies would need to follow those individuals at increased risk and assess outcomes following any invasive dental procedures, grouping by whether prophylaxis was received or not. Included case-control studies would need to match people who had developed endocarditis (and who were known to be at increased risk before undergoing an invasive dental procedure preceding the onset of endocarditis) with those at similar risk but who had not developed endocarditis. Outcomes of interest were mortality or serious adverse events requiring hospital admission; development of endocarditis following any dental procedure in a defined time period; development of endocarditis due to other non-dental causes; any recorded adverse events to the antibiotics; and cost implications of the antibiotic provision for the care of those patients who developed endocarditis.

Data collection and analysis: 

Two review authors independently selected studies for inclusion then assessed risk of bias and extracted data from the included study.

Main results: 

No randomised controlled trials (RCTs), controlled clinical trials (CCTs) or cohort studies were included. One case-control study met the inclusion criteria. It collected all the cases of endocarditis in the Netherlands over two years, finding a total of 24 people who developed endocarditis within 180 days of an invasive dental procedure, definitely requiring prophylaxis according to current guidelines, and who were at increased risk of endocarditis due to a pre-existing cardiac problem. This study included participants who died because of the endocarditis (using proxies). Controls attended local cardiology outpatient clinics for similar cardiac problems, had undergone an invasive dental procedure within the past 180 days, and were matched by age with the cases. No significant effect of penicillin prophylaxis on the incidence of endocarditis could be seen. No data were found on other outcomes.