Reply to Letter From Thornhill et al.—Infective Endocarditis Hospitalizations Before and After the 2007 American Heart Association Prophylaxis Guidelines

Abstract

We appreciate the interest of Professor Thornhill and colleagues regarding our analysis of infective endocarditis (IE) hospitalizations before and after the 2007 American Heart Association (AHA) prophylaxis guidelines.1Mackie A.S. Liu W. Savu A. Marelli A.J. Kaul P. Infective endocarditis hospitalizations before and after the 2007 American Heart Association Prophylaxis Guidelines.Can J Cardiol. 2016; 32: 942-948Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar The lack of antibiotic prophylaxis (AP) prescribing data in our study is certainly a limitation. The data source available to us unfortunately does not include AP prescription data. However, our group has previously shown that (1) the 2007 AHA guidelines resulted in a significant reduction in AP prescribing among Canadian cardiologists2Pharis C.S. Conway J. Warren A.E. Bullock A. Mackie A.S. The Impact of 2007 infective endocarditis prophylaxis guidelines on the practice of congenital heart disease specialists.Am Heart J. 2011; 161: 123-129Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar, 3Grattan M.J. Power A. Fruitman D.S. Islam S. Mackie A.S. The impact of infective endocarditis prophylaxis recommendations on the practices of pediatric and adult congenital cardiologists.Can J Cardiol. 2015; 31: 1497.e23-1497.e28Abstract Full Text Full Text PDF Scopus (12) Google Scholar; and (2) that dentists in Canada rely heavily on recommendations from patient's cardiologists as to whether or not AP is required for a given individual.4Jain P. Stevenson T. Sheppard A. et al.Antibiotic prophylaxis for infective endocarditis: knowledge and implementation of American Heart Association guidelines among dentists and dental hygienists in Alberta, Canada.J Am Dental Assoc. 2015; 146: 743-750Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar We agree with Thornhill and colleagues that the incidence of IE associated with native valve disease (either nonrheumatic valvular disease or chronic rheumatic heart disease) and streptococcal IE are most likely to be influenced by the AHA guidelines, relative to other subgroups. To investigate this further we examined the incidence of IE associated with native valve disease and streptococcal species. As in Figure 3 of our report, we excluded Streptococcus pneumoniae and groups A, B, C, D, and G. With change point analysis, no change in the population-based incidence was observed (figure not shown). Change point analysis does not stipulate when a change in the incidence should have occurred. When we specifically look before and after April 2007, we see a borderline trend (Fig. 1). The slope of incidence over time for native valve IE with streptococcal species was slightly higher after compared with before April 2007 (P = 0.057 for interaction term). More years of follow-up are needed to ascertain whether this holds true. The challenge with interpreting data from streptococcal species using International Classification of Diseases codes is that unfortunately there is no code specific to Streptococcus viridans, the organism most likely to be influenced by reducing prescriptions for AP. Drawing comparisons between our study findings and those of Dayer and colleagues is difficult, because the National Institute for Clinical Excellence guidelines differed from the AHA guidelines, and the rate of dissemination and uptake of these guidelines among clinicians might also have differed. The authors have no conflicts of interest to disclose. Infective Endocarditis Hospitalizations Before and After the 2007 American Heart Association Prophylaxis GuidelinesCanadian Journal of CardiologyVol. 32Issue 8PreviewIn 2007, the American Heart Association (AHA) published revised guidelines for infective endocarditis (IE) prophylaxis. Population-based data with respect to the potential impact of these revised guidelines are lacking. Full-Text PDF The Effect of Antibiotic Prophylaxis Guidelines on Incidence of Infective EndocarditisCanadian Journal of CardiologyVol. 32Issue 12PreviewWe congratulate Mackie et al.1 on their excellent paper that showed no significant increase in infective endocarditis (IE) following the 2007 AHA guidelines that recommend discontinuation of antibiotic prophylaxis (AP) for “moderate-risk” patients. Full-Text PDF What to Think About Antibiotic Prophylaxis and Infective EndocarditisCanadian Journal of CardiologyVol. 32Issue 8PreviewThe practice of using antibiotic prophylaxis before dental procedures dates back to the early days of antibiotics, when Northrop and Crowley—2 oral surgeons—were interested in the relationship of dental procedures to infective endocarditis (IE).1 They found that only a minority of patients with IE had a preceding dental procedure. However, they also demonstrated that antibiotics preceding dental procedures could reduce the incidence of bacteremia. In what now can only be considered a leap of faith, they concluded that there was a “responsibility” to administer antibiotics before dental procedures in individuals at risk for IE. Full-Text PDF