antibiotics and endocarditis. Evidence. Or not., page

People with 'heart murmurs' are often given 2-3g of amoxicillin one hour prior to surgical or dental procedures that might cause a bacteremia (bugs in the bloodstream that theoretically could colonize damaged heart valves and cause infective endocarditis- high morbidity and mortality).

OK. Sounds like a good enough idea. But going to the epidemiology there seems to be:

1 no evidence that 'covering' with ABs prevents endocarditis

2 no evidence that 'not covering' with ABs is linked to endocarditis

3 some evidence that you kill more people who die of anaphylaxis in previously undiagnosed penicillin allergy than you save by preventing endocarditis.

link

gold standard review

So. Your doctor or dentist is following professional guidelines that:

1 have no evidence behind them

2 may more likely kill you than save you.

I haven't seen this one brought up here, I think it is a glaring example of the medical/pharmaceutical/dental establishment accomplishing the tremendous feat of screwing over the public *and* the practitioners with one majestic leap. Hurrah.

TD

Originally posted by Relentless
I really have to wonder about this one. It just doesn't make any sense to say the risks of antibiotics outweigh the benefits in these cases.

Hello Relentless:

This is a study showing not particularly good evidence for prophylaxis in the first case:

endocarditis netherlands

This is a review article about evidence (or lack of) and risks for the prophlyaxis:

wahl

This is a nice article from the BDJ about the lack of evidence:

BDJ

First of all, the people who are prescribed antibiotics for dental procedures are those diagnosed wiht a pre-exisiting conditions such as mitral valve prolapse or a stent, something that can cause the bacteria that enters the blood stream during a dental procedure to get caught in a heart that might have something to prevent the bacteria from passing through cleanly.

Yes, that is absolutely the *theory* - and it sounds reasonable at first glance. *But*, it comes back to, where is the evidence you are doing any good by giving ABC for that theory?

1 The Cochrane link (gold standard link first post) doesn't seem to think there is any good evidence of it working.

2 The second link (this post)mentions that there are risks to prophylaxis (mainly massive anaphylaxis) - and this can *definitely* happen in people who have stated that they are *clear* of allergies.

3 The bacteremias that could cause an endocarditis are more likely to happen when the patient is brushing their teeth at home, defacating or eating, rather than in the dentists' or surgeons' chair (third link).

I don't have a problem with the theory behind antibiotic prophylaxis - but I do have a problem with it not being based on good evidence and patients not being told that there are risks, and that the benefits may not be there in the first place - it's not really informed consent, imo.

Most of these people by the time they have a need for this antibiotic use are of an age where they already know whether or not they need to avoid penicillin, in which case another antibiotic can be used.

I'll see if I can find a link on undiagnosed allergy to penicillin and big anaphylaxis reactions - even on people who have taken it before with no problems.

In addition, it is normally used as a preventative, not a normal run (7 - 10 days) for an existing bacterial infection. Usually taking a dose prior to the procedure, just as now it is common (at least in the US) to give you a shot of antibiotic just prior to surgery.

Yup - a big shot one hour pre-op. Not worried about resistance so much, which you could get on a 7-10 day course, rather the anaphyalxis thing to a big dose.

There you go - case report on someone who had been taking penicillin v daily for sickle cell, and had a big reaction to a cephalosporin (10% crossover with penicillin). So not being allergic, doesn't actually mean you aren't allergic, if you see what I mean.

reaction

No evidence that it prevents? All I know is the only reason my DH's MVP was diagnosed was because he developed a heart problem after a routine dental cleaning. It was quite frightening and ultimately led to them discovering the MVP, at which point he was put on the protocol. He is also now stuck forever on heart regulation medication that he cannot ever stop. How many of you are aware that once you are put on a heart regulation medication it is considered to risky to ever stop them again? So one incident that required heart regulation, once resolved leaves you forever on medication that seriously impacts your life.

Read the Cochrane report (gold standard) and the BDJ report (this one) - and I am really not sure that there is *evidence* that the scaling could have caused the problem. He could well have been getting a bacteremia every time he brushed, flossed, or went to the bathroom. I don't think cause and effect is established, and if so, I think the guidelines should at least reflect that so patients can make an informed choice about risks and benefits of the procedure, rather than being told 'it works'.

Quite frankly I see a lot more suspicious activity in the attacks of antibiotics over the past few years. Compared to all the other drugs prescribed like candy as preventatives (statins, BP medications, etc.) the side affects of antibiotics are lame and all the hoopla making Drs. hold off on prescribing them are causing more and more infections occur and to go to far instead of nipping it in the bud. That's been my experience and I have seen way too many cases of this in family and friends.

I'm not getting into prescription for viral sore throats, resistance etc - it's a whole other issue, and I'm not going there.

I'm more concerned about this very narrow and specific topic - I really think it was a good idea at the time, but modern evidence based medicine/dentistry is showing that really - it may not be doing much good for the patient, or even harming them.



TD

Originally posted by TaupeDragon

Yup - a big shot one hour pre-op. Not worried about resistance so much, which you could get on a 7-10 day course, rather the anaphyalxis thing to a big dose.

Then it seems to me the big concern should be over pre-op administration, not Dental work.

Edit:

Your Original Link #2

Authors' conclusions
There is no evidence about whether penicillin prophylaxis is effective or ineffective against bacterial endocarditis in people at risk who are about to undergo an invasive dental procedure. There is a lack of evidence to support published guidelines in this area. It is not clear whether the potential harms and costs of penicillin administration outweigh any beneficial effect.

So basically a study that concluded "It is not clear" & there is no evidence whether it is effective or ineffective. Okay then.

[edit on 9/22/2006 by Relentless]

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