Infective endocarditis following invasive dental procedures: IDEA case-crossover study.

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BACKGROUND: Infective endocarditis is a heart infection with a first-year mortality rate of ≈ 30%. It has long been thought that infective endocarditis is causally associated with bloodstream seeding with oral bacteria in ≈ 40-45% of cases. This theorem led guideline committees to recommend that individuals at increased risk of infective endocarditis should receive antibiotic prophylaxis before undergoing invasive dental procedures. However, to the best of our knowledge, there has never been a clinical trial to prove the efficacy of antibiotic prophylaxis and there is no good-quality evidence to link invasive dental procedures with infective endocarditis. Many contend that oral bacteria-related infective endocarditis is more likely to result from daily activities (e.g. tooth brushing, flossing and chewing), particularly in those with poor oral hygiene.

OBJECTIVE: The aim of this study was to determine if there is a temporal association between invasive dental procedures and subsequent infective endocarditis, particularly in those at high risk of infective endocarditis.

DESIGN: This was a self-controlled, case-crossover design study comparing the number of invasive dental procedures in the 3 months immediately before an infective endocarditis-related hospital admission with that in the preceding 12-month control period.

SETTING: The study took place in the English NHS.

PARTICIPANTS: All individuals admitted to hospital with infective endocarditis between 1 April 2010 and 31 March 2016 were eligible to participate.

INTERVENTIONS: This was an observational study; therefore, there was no intervention.

MAIN OUTCOME MEASURE: The outcome measure was the number of invasive and non-invasive dental procedures in the months before infective endocarditis-related hospital admission.

DATA SOURCES: NHS Digital provided infective endocarditis-related hospital admissions data and dental procedure data were obtained from the NHS Business Services Authority.

RESULTS: The incidence rate of invasive dental procedures decreased in the 3 months before infective endocarditis-related hospital admission (incidence rate ratio 1.34, 95% confidence interval 1.13 to 1.58). Further analysis showed that this was due to loss of dental procedure data in the 2-3 weeks before any infective endocarditis-related hospital admission.

LIMITATIONS: We found that urgent hospital admissions were a common cause of incomplete courses of dental treatment and, because there is no requirement to record dental procedure data for incomplete courses, this resulted in a significant loss of dental procedure data in the 2-3 weeks before infective endocarditis-related hospital admissions. The data set was also reduced because of the NHS Business Services Authority's 10-year data destruction policy, reducing the power of the study. The main consequence was a loss of dental procedure data in the critical 3-month case period of the case-crossover analysis (immediately before infective endocarditis-related hospital admission), which did not occur in earlier control periods. Part of the decline in the rate of invasive dental procedures may also be the result of the onset of illness prior to infective endocarditis-related hospital admission, and part may be due to other undefined causes.

CONCLUSIONS: The loss of dental procedure data in the critical case period immediately before infective endocarditis-related hospital admission makes interpretation of the data difficult and raises uncertainty over any conclusions that can be drawn from this study.

FUTURE WORK: We suggest repeating this study elsewhere using data that are unafflicted by loss of dental procedure data in the critical case period.

TRIAL REGISTRATION: This trial is registered as ISRCTN11684416.

FUNDING: This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in ; Vol. 26, No. 28. See the NIHR Journals Library website for further project information.

Infective endocarditis is a life-threatening infection of the heart valves. Most people are at low risk of infective endocarditis. However, those with certain cardiac conditions are at moderate risk of infective endocarditis, and those with artificial or repaired heart valves, a history of infective endocarditis and certain congenital heart conditions are at high risk of infective endocarditis. In around 40–45% of cases, oral bacteria are the cause of infective endocarditis. For many years, those people at moderate or high risk of infective endocarditis were given antibiotics (antibiotic prophylaxis) before invasive dental procedures such as extractions to reduce the risk of infective endocarditis. There is no good-quality evidence, however, to support the effectiveness of antibiotic prophylaxis, or the link between invasive dental procedures and infective endocarditis. Many believe that the oral bacteria that cause infective endocarditis are more likely to enter the blood during daily activities (e.g. toothbrushing, flossing or chewing), particularly in those with poor oral hygiene, than on the rare occasions when invasive dental procedures are performed. The aim of this study was to link English NHS data on infective endocarditis-related hospital admissions and dental treatments to determine if infective endocarditis is more likely in the weeks immediately after an invasive dental procedure than at any other time. When we linked the data sets and plotted the occurrence of different dental treatments over the year before infective endocarditis-related hospital admission, we detected a problem in the way that dental data were recorded. Unfortunately, there was a failure to collect dental procedure data when courses of treatment were incomplete. As one of the most common reasons for not completing a course of treatment was emergency admission to hospital, this meant that the number of dental procedures recorded decreased in the weeks before any emergency hospital admission. We have attempted to correct for this, but the data loss has affected the data quality. Although the data suggest an association between invasive dental procedures and infective endocarditis in individuals at high risk of infective endocarditis, the certainty of this association has been weakened.