Concern is growing about the overuse of antibiotics and the subsequent rise in antibiotic-resistant bacteria. Antibiotics are commonly used to prevent heart valve infections in susceptible patients undergoing dental or other surgical procedures. Although this practice has been standard for nearly 50 years, little evidence exists that it works. This Issue Brief summarizes a population-based study that challenges the link between dental procedures and heart valve infections, and illustrates the difficulty in incorporating new evidence into existing guidelines and longstanding practices

Strom, Brian L

English

ScholarlyCommons@Penn

University of PennsylvaniaScholarlyCommonsIssue Briefs Leonard Davis Institute of Health Economics3-20-2001When Data Conflict With Practice: Rethinking theuse of Prophylactic Antibiotics Before DentalTreatmentBrian L. StromFollow this and additional works at: http://repository.upenn.edu/ldi_issuebriefsThis paper is posted at ScholarlyCommons. http://repository.upenn.edu/ldi_issuebriefs/19For more information, please contact repository@pobox.upenn.edu.Strom, Brian L.. When Data Conflict With Practice: Rethinking the use of Prophylactic Antibiotics Before Dental Treatment. LDIIssue Briefs. 2001; 6 (6). http://ldi.upenn.edu/policy/issue-briefs/2001/03/20/when-data-conflict-with-practice-rethinking-the-use-of-prophylactic-antibiotics-before-dental-treatmentWhen Data Conflict With Practice: Rethinking the use of ProphylacticAntibiotics Before Dental TreatmentAbstractConcern is growing about the overuse of antibiotics and the subsequent rise in antibiotic-resistant bacteria.Antibiotics are commonly used to prevent heart valve infections in susceptible patients undergoing dental orother surgical procedures. Although this practice has been standard for nearly 50 years, little evidence existsthat it works. This Issue Brief summarizes a population-based study that challenges the link between dentalprocedures and heart valve infections, and illustrates the difficulty in incorporating new evidence into existingguidelines and longstanding practices.LicenseThis work is licensed under a Creative Commons Attribution-No Derivative Works 4.0 License.This brief is available at ScholarlyCommons: http://repository.upenn.edu/ldi_issuebriefs/19Leonard Davis Institute of Health EconomicsLDI Issue BriefVolume 6, Number 6March 2001Brian L. Strom, MD, MPHLDI Senior Fellow,Professor of Biostatistics andEpidemiologyUniversity of PennsylvaniaWhen Data Conflict with Practice:Rethinking the Use of Prophylactic Antibioticsbefore Dental TreatmentEditor’s note:  Concern is growing about the overuse of antibiotics and the subsequentrise in antibiotic-resistant bacteria. Antibiotics are commonly used to prevent heartvalve infections in susceptible patients undergoing dental or other surgical procedures.Although this practice has been standard for nearly 50 years, little evidence exists thatit works. This Issue Brief summarizes a population-based study that challenges thelink between dental procedures and heart valve infections, and illustrates the difficultyin incorporating new evidence into existing guidelines and longstanding practices.Clinicians routinely prescribe antibiotics to certain patients before dental treatmentsto prevent infective endocarditis, a rare but potentially fatal infection of the heart’sinner lining or valves. Conventional wisdom suggests that patients with cardiacabnormalities are at risk for endocarditis from dental and other procedures that mightintroduce bacteria into their bloodstream.  However, the effectiveness of this practice(known as antibiotic prophylaxis) has not been proven.• The clinical recommendations are based on anecdotes, studies of bacteria in thebloodstream  after procedures, and animal models.  The low incidence of diseasehas made randomized human trials of antibiotic effectiveness impractical.• The incidence of infective endocarditis has remained the same even after theintroduction of widespread antibiotic prophylaxis. This could imply that antibioticprophylaxis is not effective, or not given to the appropriate “at-risk” population.• The risks and benefits of antibiotic prophylaxis on an individual and communitylevel are undergoing increasing scrutiny.  Does the cost of antibiotics, and the rarebut real risk for adverse reactions, outweigh the possible benefit to the patient?On a population level, does widespread antibiotic prophylaxis reduce the incidenceof infective endocarditis enough to justify the possible development of drug-resistant bacteria?Since 1955, the American Heart Association (AHA) and other professionalorganizations have recommended that antibiotic prophylaxis be given to at-riskpatients before dental procedures. The AHA’s guidelines have been revised nine times,with the latest update in 1997.  The last revision narrowed the range of patientsconsidered at risk for endocarditis, specified the dental procedures thought to be highrisk, and simplified the recommended dosages.The use of antibiotics toprevent endocarditis is notproven effectiveProfessional guidelines haveevolved slowly, but the basicpremise remains the same• The guidelines continue to assume a link between many dental procedures and theonset of endocarditis.  They presume the effectiveness of antibiotics in preventingendocarditis in patients at risk, including those with congenital heartmalformations, acquired valvular defects (such as rheumatic heart disease),prosthetic valves, and previous endocarditis.• The guidelines target dental procedures that involve the greatest risk of bleeding,assuming that these procedures also pose the greatest risk of introducing bacteriainto the bloodstream.• Although the guidelines have produced a clinical and legal standard of care,compliance with these standards vary.  A recent study of patients undergoingcardiac evaluation found that about 40% of those meeting the AHA criteria forantibiotics did not get them, and about 25% of those not meeting the criteriareceived antibiotics anyway.Strom and colleagues conducted a case-control study to evaluate and quantify riskfactors for infective endocarditis, especially those considered by the AHA to beindications for using antibiotics prophylactically.• From August 1988 to November 1990, the investigators identified adults withinfective endocarditis in 54 hospitals in Philadelphia and surrounding counties.These patients were interviewed by telephone to ascertain possible risk factors.Medical and dental records were obtained to validate self-reported information.• The study included 379 patient with definite, probable or possible endocarditis.The investigators excluded endocarditis associated with intravenous drug use oracquired in the hospital; this left 287 patients.  Of these, 273 (95%) completed thestudy interview. These patients were compared with an equal number of randomlyselected community residents matched for age, sex and neighborhood of residence.• The study compared the relationships between previous dental work performed on“case-patients” (those with infective endocarditis) and previous dental workperformed on “controls” (community residents without endocarditis).The study confirmed the importance of preexisting cardiac abnormalities as principalrisk factors for endocarditis.• A patient-reported history of heart valve abnormality was highly associated withinfective endocarditis.  Case-patients were nearly 17 times more likely than controlsto report any valvular abnormality; they were 75 times more likely than controls toreport previous heart valve surgery, 37 times more likely to report previousendocarditis, 19 times more likely to report mitral valve prolapse, and 7 times morelikely to report a heart murmur.• Only a small proportion  (10.6%) of case-patients had both a known cardiacabnormality and recent dental treatment.  This indicates that the proportion ofendocarditis even theoretically preventable with antibiotics is small.The results showed that neither dental work, in general, nor any individual procedure,was significantly associated with infective endocarditis except, possibly, toothextraction.Population-based studycompares patients withendocarditis to a randomsample of healthycommunity residentsStudy confirms that heartvalve abnormalities arerisk factors forendocarditisResults suggest that dentalprocedures are not a riskfactor for endocarditis,even in at-risk patientsPOLICY IMPLICATIONSContinued on back.• In the previous two months, about 17% of the case-patients and 14% of thecontrols had dental treatment; this increased to 23% of both case-patients andcontrols in the three months prior to the study date.  The similar percentages ofprevious dental procedures among people with and without endocarditis suggeststhat dental procedures are not a risk factor for endocarditis.• Even among patients and controls with known cardiac abnormalities—the target ofantibiotic prophylaxis—the risk for endocarditis was not increased by dentaltreatment.  Of the case-patients with a valvular abnormality, about 20% had haddental treatment within two months of the study date; about 24% of the controlshad a similar exposure.• Tooth extractions in the previous two months were reported in 6 case-patients, butno controls, indicating a possible risk.  However, the number is too small toeliminate the possibility that this occurred by chance.  In addition, this risk did notoccur in the group of participants with valvular abnormalities, the target ofantibiotic prophylaxis.• Few participants in the study received antibiotic prophylaxis; however, the risk forendocarditis remained the same, regardless of the use of antibiotics.Strom and colleagues conducted analyses within certain groups in the study toidentify other potential risk factors for infective endocarditis, including underlyingmedical conditions and oral hygiene practices.  Because of small numbers of patientsin certain groups, these results are suggestive, but not conclusive.• Flossing daily was associated with a slightly reduced risk for endocarditis. Thissuggests that patients with heart valve abnormalities should be vigilant about oralhygiene.• No association was found between endocarditis and frequency of routine dentalcare, use and frequency of tooth brushing, or use of a toothpick, oral irrigator, orgum stimulator.• Case-patients were nearly 17 times more likely than controls to have severe kidneydisease, and many of them were undergoing dialysis. The study could notdetermine whether the underlying disease itself or the procedures used to treat thedisease were independent risk factors for endocarditis.This study provides the most compelling evidence to date that antibiotic prophylaxisin at-risk patients is not effective in preventing endocarditis. Furthermore, given theexpense and difficulty of doing further studies on this rare condition, this evidence isunlikely to be supplemented for a long time. Given the low incidence of the disease,the failures that occur even with recommended antibiotics, and the cost and risk ofadverse reactions to the antibiotics, the study should lead professional organizations toreconsider their recommendations.  However, changing standards and clinical practiceis not an easy thing to accomplish.• The guideline development process is often long and cumbersome.  Since this studywas originally published in 1998, the American Heart Association and AmericanDental Association have indicated that they will consider the evidence when theyupdate the 1997 guidelines, which has not yet occurred. International guidelinesare evolving even more slowly, with British guidelines last published in 1993.Flossing teeth daily mayreduce risk of endocarditisThis Issue Brief is based on the following articles:  B.L. Strom, E. Abrutyn, J.A. Berlin, J.L. Kinman, R.S. Feldman, P.D. Stolley, M.E. Levison,O.M. Korzeniowski, D. Kaye.  Risk factors for infective endocarditis: oral hygiene and nondental exposures.  Circulation, December 2000, vol.102, pp. 2842-2848; B.L. Strom, E. Abrutyn, J.A. Berlin, J.L. Kinman, R.S. Feldman, P.D. Stolley, M.E. Levison, O.M. Korzeniowski, D. Kaye.Dental and cardiac risk factors for infective endocarditis: a population-based, case-control study.  Annals of Internal Medicine, Nov. 15, 1998, vol.129, pp. 761-769.Published by the Leonard Davis Institute of Health Economics, University of Pennsylvania, 3641 Locust Walk, Philadelphia, PA 19104-6218,215-898-5611.Janet Weiner, MPH, Associate Director for Health Policy, EditorDavid A. Asch, MD, MBA, Executive DirectorIssue Briefs synthesize the results of research by LDI’s Senior Fellows, a consortium of Penn scholars studying medical, economic, and social andethical issues that influence how health care is organized, financed, managed, and delivered in the United States and internationally. The LDI is acooperative venture among Penn schools including Dental Medicine, Medicine, Nursing and Wharton. For additional information on this or otherIssue Briefs, contact Janet Weiner (e-mail: weinerja@mail.med.upenn.edu; 215-573-9374).Visit us on the web at www.upenn.edu/ldi© 2001 Leonard Davis InstituteNonprofit OrganizationU.S. PostageP  A  I  DPermit No. 2563Philadelphia, PA 19104Issue Brief Published by theLeonard Davis Instituteof Health EconomicsUniversity of Pennsylvania3641 Locust WalkPhiladelphia, PA 19104-6218215.898.5611fax 215.898.0229ADDRESS CORRECTION REQUESTEDPOLICY IMPLICATIONSContinued• A number of commentators have suggested that the guidelines be refocused torecommend antibiotic prophylaxis only for patients at greatest risk for endocarditisand its resulting complications, namely, patients with previous endocarditis or thosewith prosthetic valves.  Doing so might retain most of the potential benefits ofantibiotic prophylaxis, while minimizing overall exposure to unnecessaryantibiotics.• Until professional guidelines are changed, it will be difficult to change clinicalpractice.  Clinicians will likely follow their professional association’s guidelineswhen faced with fear of malpractice claims and lingering uncertainty about how toapply population-based results to individual patients.• Recognizing that clinicians need more information about the therapies theyprescribe, the federal Agency for Healthcare Research and Quality has recentlyfunded seven universities to develop Centers for Education and Research inTherapeutics (CERTs).  One of the CERTs’ primary goals is increase awareness ofthe risks and benefits of new and existing drugs; the University of Pennsylvania’scenter, funded in September 2000, is focusing on appropriate use of antibiotics.

When Data Conflict With Practice: Rethinking the use of Prophylactic Antibiotics Before Dental Treatment

Kosmopolis

University of Pennsylvania
ScholarlyCommons
Issue Briefs Leonard Davis Institute of Health Economics
3-20-2001
When Data Conflict With Practice: Rethinking the
use of Prophylactic Antibiotics Before Dental
Treatment
Brian L. Strom
Follow this and additional works at: http://repository.upenn.edu/ldi_issuebriefs
This paper is posted at ScholarlyCommons. http://repository.upenn.edu/ldi_issuebriefs/19
For more information, please contact repository@pobox.upenn.edu.
Strom, Brian L.. When Data Conflict With Practice: Rethinking the use of Prophylactic Antibiotics Before Dental Treatment. LDI
Issue Briefs. 2001; 6 (6). http://ldi.upenn.edu/policy/issue-briefs/2001/03/20/when-data-conflict-with-practice-rethinking-the-use-
of-prophylactic-antibiotics-before-dental-treatment
When Data Conflict With Practice: Rethinking the use of Prophylactic
Antibiotics Before Dental Treatment
Abstract
Concern is growing about the overuse of antibiotics and the subsequent rise in antibiotic-resistant bacteria.
Antibiotics are commonly used to prevent heart valve infections in susceptible patients undergoing dental or
other surgical procedures. Although this practice has been standard for nearly 50 years, little evidence exists
that it works. This Issue Brief summarizes a population-based study that challenges the link between dental
procedures and heart valve infections, and illustrates the difficulty in incorporating new evidence into existing
guidelines and longstanding practices.
License
This work is licensed under a Creative Commons Attribution-No Derivative Works 4.0 License.
This brief is available at ScholarlyCommons: http://repository.upenn.edu/ldi_issuebriefs/19
Leonard Davis Institute of Health Economics
LDI Issue Brief
Volume 6, Number 6
March 2001
Brian L. Strom, MD, MPH
LDI Senior Fellow,
Professor of Biostatistics and
Epidemiology
University of Pennsylvania
When Data Conflict with Practice:
Rethinking the Use of Prophylactic Antibiotics
before Dental Treatment
Editor’s note:  Concern is growing about the overuse of antibiotics and the subsequent
rise in antibiotic-resistant bacteria. Antibiotics are commonly used to prevent heart
valve infections in susceptible patients undergoing dental or other surgical procedures.
Although this practice has been standard for nearly 50 years, little evidence exists that
it works. This Issue Brief summarizes a population-based study that challenges the
link between dental procedures and heart valve infections, and illustrates the difficulty
in incorporating new evidence into existing guidelines and longstanding practices.
Clinicians routinely prescribe antibiotics to certain patients before dental treatments
to prevent infective endocarditis, a rare but potentially fatal infection of the heart’s
inner lining or valves. Conventional wisdom suggests that patients with cardiac
abnormalities are at risk for endocarditis from dental and other procedures that might
introduce bacteria into their bloodstream.  However, the effectiveness of this practice
(known as antibiotic prophylaxis) has not been proven.
• The clinical recommendations are based on anecdotes, studies of bacteria in the
bloodstream  after procedures, and animal models.  The low incidence of disease
has made randomized human trials of antibiotic effectiveness impractical.
• The incidence of infective endocarditis has remained the same even after the
introduction of widespread antibiotic prophylaxis. This could imply that antibiotic
prophylaxis is not effective, or not given to the appropriate “at-risk” population.
• The risks and benefits of antibiotic prophylaxis on an individual and community
level are undergoing increasing scrutiny.  Does the cost of antibiotics, and the rare
but real risk for adverse reactions, outweigh the possible benefit to the patient?
On a population level, does widespread antibiotic prophylaxis reduce the incidence
of infective endocarditis enough to justify the possible development of drug-
resistant bacteria?
Since 1955, the American Heart Association (AHA) and other professional
organizations have recommended that antibiotic prophylaxis be given to at-risk
patients before dental procedures. The AHA’s guidelines have been revised nine times,
with the latest update in 1997.  The last revision narrowed the range of patients
considered at risk for endocarditis, specified the dental procedures thought to be high
risk, and simplified the recommended dosages.
The use of antibiotics to
prevent endocarditis is not
proven effective
Professional guidelines have
evolved slowly, but the basic
premise remains the same
• The guidelines continue to assume a link between many dental procedures and the
onset of endocarditis.  They presume the effectiveness of antibiotics in preventing
endocarditis in patients at risk, including those with congenital heart
malformations, acquired valvular defects (such as rheumatic heart disease),
prosthetic valves, and previous endocarditis.
• The guidelines target dental procedures that involve the greatest risk of bleeding,
assuming that these procedures also pose the greatest risk of introducing bacteria
into the bloodstream.
• Although the guidelines have produced a clinical and legal standard of care,
compliance with these standards vary.  A recent study of patients undergoing
cardiac evaluation found that about 40% of those meeting the AHA criteria for
antibiotics did not get them, and about 25% of those not meeting the criteria
received antibiotics anyway.
Strom and colleagues conducted a case-control study to evaluate and quantify risk
factors for infective endocarditis, especially those considered by the AHA to be
indications for using antibiotics prophylactically.
• From August 1988 to November 1990, the investigators identified adults with
infective endocarditis in 54 hospitals in Philadelphia and surrounding counties.
These patients were interviewed by telephone to ascertain possible risk factors.
Medical and dental records were obtained to validate self-reported information.
• The study included 379 patient with definite, probable or possible endocarditis.
The investigators excluded endocarditis associated with intravenous drug use or
acquired in the hospital; this left 287 patients.  Of these, 273 (95%) completed the
study interview. These patients were compared with an equal number of randomly
selected community residents matched for age, sex and neighborhood of residence.
• The study compared the relationships between previous dental work performed on
“case-patients” (those with infective endocarditis) and previous dental work
performed on “controls” (community residents without endocarditis).
The study confirmed the importance of preexisting cardiac abnormalities as principal
risk factors for endocarditis.
• A patient-reported history of heart valve abnormality was highly associated with
infective endocarditis.  Case-patients were nearly 17 times more likely than controls
to report any valvular abnormality; they were 75 times more likely than controls to
report previous heart valve surgery, 37 times more likely to report previous
endocarditis, 19 times more likely to report mitral valve prolapse, and 7 times more
likely to report a heart murmur.
• Only a small proportion  (10.6%) of case-patients had both a known cardiac
abnormality and recent dental treatment.  This indicates that the proportion of
endocarditis even theoretically preventable with antibiotics is small.
The results showed that neither dental work, in general, nor any individual procedure,
was significantly associated with infective endocarditis except, possibly, tooth
extraction.
Population-based study
compares patients with
endocarditis to a random
sample of healthy
community residents
Study confirms that heart
valve abnormalities are
risk factors for
endocarditis
Results suggest that dental
procedures are not a risk
factor for endocarditis,
even in at-risk patients
POLICY IMPLICATIONS
Continued on back.
• In the previous two months, about 17% of the case-patients and 14% of the
controls had dental treatment; this increased to 23% of both case-patients and
controls in the three months prior to the study date.  The similar percentages of
previous dental procedures among people with and without endocarditis suggests
that dental procedures are not a risk factor for endocarditis.
• Even among patients and controls with known cardiac abnormalities—the target of
antibiotic prophylaxis—the risk for endocarditis was not increased by dental
treatment.  Of the case-patients with a valvular abnormality, about 20% had had
dental treatment within two months of the study date; about 24% of the controls
had a similar exposure.
• Tooth extractions in the previous two months were reported in 6 case-patients, but
no controls, indicating a possible risk.  However, the number is too small to
eliminate the possibility that this occurred by chance.  In addition, this risk did not
occur in the group of participants with valvular abnormalities, the target of
antibiotic prophylaxis.
• Few participants in the study received antibiotic prophylaxis; however, the risk for
endocarditis remained the same, regardless of the use of antibiotics.
Strom and colleagues conducted analyses within certain groups in the study to
identify other potential risk factors for infective endocarditis, including underlying
medical conditions and oral hygiene practices.  Because of small numbers of patients
in certain groups, these results are suggestive, but not conclusive.
• Flossing daily was associated with a slightly reduced risk for endocarditis. This
suggests that patients with heart valve abnormalities should be vigilant about oral
hygiene.
• No association was found between endocarditis and frequency of routine dental
care, use and frequency of tooth brushing, or use of a toothpick, oral irrigator, or
gum stimulator.
• Case-patients were nearly 17 times more likely than controls to have severe kidney
disease, and many of them were undergoing dialysis. The study could not
determine whether the underlying disease itself or the procedures used to treat the
disease were independent risk factors for endocarditis.
This study provides the most compelling evidence to date that antibiotic prophylaxis
in at-risk patients is not effective in preventing endocarditis. Furthermore, given the
expense and difficulty of doing further studies on this rare condition, this evidence is
unlikely to be supplemented for a long time. Given the low incidence of the disease,
the failures that occur even with recommended antibiotics, and the cost and risk of
adverse reactions to the antibiotics, the study should lead professional organizations to
reconsider their recommendations.  However, changing standards and clinical practice
is not an easy thing to accomplish.
• The guideline development process is often long and cumbersome.  Since this study
was originally published in 1998, the American Heart Association and American
Dental Association have indicated that they will consider the evidence when they
update the 1997 guidelines, which has not yet occurred. International guidelines
are evolving even more slowly, with British guidelines last published in 1993.
Flossing teeth daily may
reduce risk of endocarditis
This Issue Brief is based on the following articles:  B.L. Strom, E. Abrutyn, J.A. Berlin, J.L. Kinman, R.S. Feldman, P.D. Stolley, M.E. Levison,
O.M. Korzeniowski, D. Kaye.  Risk factors for infective endocarditis: oral hygiene and nondental exposures.  Circulation, December 2000, vol.
102, pp. 2842-2848; B.L. Strom, E. Abrutyn, J.A. Berlin, J.L. Kinman, R.S. Feldman, P.D. Stolley, M.E. Levison, O.M. Korzeniowski, D. Kaye.
Dental and cardiac risk factors for infective endocarditis: a population-based, case-control study.  Annals of Internal Medicine, Nov. 15, 1998, vol.
129, pp. 761-769.
Published by the Leonard Davis Institute of Health Economics, University of Pennsylvania, 3641 Locust Walk, Philadelphia, PA 19104-6218,
215-898-5611.
Janet Weiner, MPH, Associate Director for Health Policy, Editor
David A. Asch, MD, MBA, Executive Director
Issue Briefs synthesize the results of research by LDI’s Senior Fellows, a consortium of Penn scholars studying medical, economic, and social and
ethical issues that influence how health care is organized, financed, managed, and delivered in the United States and internationally. The LDI is a
cooperative venture among Penn schools including Dental Medicine, Medicine, Nursing and Wharton. For additional information on this or other
Issue Briefs, contact Janet Weiner (e-mail: weinerja@mail.med.upenn.edu; 215-573-9374).
Visit us on the web at www.upenn.edu/ldi
© 2001 Leonard Davis Institute
Nonprofit Organization
U.S. Postage
P  A  I  D
Permit No. 2563
Philadelphia, PA 19104
Issue Brief
Published by the
Leonard Davis Institute
of Health Economics
University of Pennsylvania
3641 Locust Walk
Philadelphia, PA 19104-6218
215.898.5611
fax 215.898.0229
ADDRESS CORRECTION REQUESTED
POLICY IMPLICATIONS
Continued
• A number of commentators have suggested that the guidelines be refocused to
recommend antibiotic prophylaxis only for patients at greatest risk for endocarditis
and its resulting complications, namely, patients with previous endocarditis or those
with prosthetic valves.  Doing so might retain most of the potential benefits of
antibiotic prophylaxis, while minimizing overall exposure to unnecessary
antibiotics.
• Until professional guidelines are changed, it will be difficult to change clinical
practice.  Clinicians will likely follow their professional association’s guidelines
when faced with fear of malpractice claims and lingering uncertainty about how to
apply population-based results to individual patients.
• Recognizing that clinicians need more information about the therapies they
prescribe, the federal Agency for Healthcare Research and Quality has recently
funded seven universities to develop Centers for Education and Research in
Therapeutics (CERTs).  One of the CERTs’ primary goals is increase awareness of
the risks and benefits of new and existing drugs; the University of Pennsylvania’s
center, funded in September 2000, is focusing on appropriate use of antibiotics.


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When Data Conflict With Practice: Rethinking the use of Prophylactic Antibiotics Before Dental Treatment

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