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Canadian Journal of Cardiology

The Effect of Antibiotic Prophylaxis Guidelines on Incidence of Infective Endocarditis

Published:March 03, 2016DOI:https://doi.org/10.1016/j.cjca.2016.02.074
      We congratulate Mackie et al.
      • Mackie A.S.
      • Liu W.
      • Savu A.
      • Marelli A.J.
      • Kaul P.
      Infective endocarditis hospitalizations before and after the 2007 American Heart Association Prophylaxis Guidelines.
      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.
      However, we note the falls in native valve predisposing conditions (nonrheumatic valvular disease plus chronic rheumatic heart disease) and streptococci-associated IE—the groups most likely to be affected by stopping AP for moderate-risk patients, plateau or even rise after 2007 (Fig. 1, data extracted using DigitizeIt).
      Figure thumbnail gr1
      Figure 1Proportion of cases due to native valve heart disease or streptococci—from the paper by Mackie et al.
      • Mackie A.S.
      • Liu W.
      • Savu A.
      • Marelli A.J.
      • Kaul P.
      Infective endocarditis hospitalizations before and after the 2007 American Heart Association Prophylaxis Guidelines.
      Lack of prescribing data makes it difficult to evaluate the presence or absence of a causal relationship between changes in AP guidelines and the magnitude and timing of changes in IE incidence. Nonetheless, most studies assessing the effect of restricting AP to those at high risk show no, or minimal, impact.
      The Morris and Webb editorial
      • Morris A.W.
      • Webb G.D.
      What to think about antibiotic prophylaxis and infective endocarditis.
      overviews the AP controversy, including our paper showing an increase in IE incidence following the 2008 NICE guidelines recommending AP cessation.
      • Dayer M.J.
      • Jones S.
      • Prendergast B.
      • et al.
      Incidence of infective endocarditis in England, 2000-13: a secular trend, interrupted time-series analysis.
      Although other studies examined the cessation of AP for moderate-risk patients, our studies are the only ones that examined cessation of AP for those at high risk as well. Furthermore, our incidence data were coupled with data quantifying the fall in AP prescribing. Although we agree that it is unlikely that all the IE incidence increase we observed was due to guideline change, we did not find evidence that population-based changes confounded the results—as the editorial suggests.
      Most studies examining the effects of restricting AP to high-risk patients support the AHA guidelines. Our data also support these guidelines but suggest that stopping AP altogether, as occurred in the UK, could be a step too far and carry significant risk for patients.
      • Dayer M.J.
      • Jones S.
      • Prendergast B.
      • et al.
      Incidence of infective endocarditis in England, 2000-13: a secular trend, interrupted time-series analysis.
      • Thornhill M.H.
      • Dayer M.
      • Lockhart P.B.
      • et al.
      Guidelines on prophylaxis to prevent infective endocarditis.
      Although the 2015 NICE guideline review referred to in the editorial decided to maintain its guidance, the European Society of Cardiology, which produces guidance for the whole of Europe, examined the same evidence and drew the opposite conclusion—strongly recommending continuation of AP for high-risk patients. The NICE review was controversial in the UK, particularly because it did not appear to consider the risk of its decision for patients.
      • Thornhill M.H.
      • Dayer M.
      • Lockhart P.B.
      • et al.
      Guidelines on prophylaxis to prevent infective endocarditis.
      The result is confusion about which guidelines to follow. Recent changes in UK law, however, require that patients are provided with all the information they need to make a decision for themselves
      • Thornhill M.H.
      • Dayer M.
      • Lockhart P.B.
      • et al.
      Guidelines on prophylaxis to prevent infective endocarditis.
      and this may result in a renewed rise in UK-AP prescribing for those at high risk.

      Disclosures

      The authors have no conflicts of interest to disclose.

      References

        • Mackie 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: 942-948
        • Morris A.W.
        • Webb G.D.
        What to think about antibiotic prophylaxis and infective endocarditis.
        Can J Cardiol. 2016; 32: 933-934
        • Dayer M.J.
        • Jones S.
        • Prendergast B.
        • et al.
        Incidence of infective endocarditis in England, 2000-13: a secular trend, interrupted time-series analysis.
        Lancet. 2015; 385: 1219-1228
        • Thornhill M.H.
        • Dayer M.
        • Lockhart P.B.
        • et al.
        Guidelines on prophylaxis to prevent infective endocarditis.
        Br Den J. 2016; 220: 51-56

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