A
BSTRACTS
EDITED BY THOMAS J. LIESEGANG, MD
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Evidence-Based Medicine: Principles for Applying the
Users’ Guides to Patient Care. Guyatt GH,* Haynes RB,
Jaeschke RZ, Cook DJ, Green L, Naylor CD, Wilson MC,
Richardson WS for the Evidence-Based Medicine Work-
ing Group. JAMA 2000;284:1290 –1296.
T
HIS ARTICLE IS PART OF A SERIES THAT PROVIDES
clinicians with strategies and tools to interpret and
integrate evidence from published research in their care of
patients. The two key principles for applying all the
articles in this series to patient care relate to the value-
laden nature of clinical decisions and to the hierarchy of
evidence postulated by evidence-based medicine. Clini-
cians need to be able to distinguish high from low quality
in primary studies, systematic reviews, practice guidelines,
and other integrative research focused on management
recommendations. An evidence-based practitioner must
also understand the patient’s circumstances or predica-
ment; identify knowledge gaps and frame questions to fill
those gaps; conduct an efficient literature search; critically
appraise the research evidence; and apply that evidence to
patient care. Treatment judgments, however, often reflect
clinician or societal values concerning whether interven-
tion benefits are worth the cost. Many unanswered ques-
tions concerning how to elicit preferences and how to
incorporate them in clinical encounters constitute an
enormously challenging frontier for evidence-based medi-
cine. Time limitation remains the biggest obstacle to
evidence-based practice but clinicians should seek evi-
dence from as high in the appropriate hierarchy of evi-
dence as possible and every clinical decision should be
geared toward the particular circumstances of the pa-
tient.— author’s abstract.
*Department of Clinical Epidemiology and Biostatistics, Room 2C12,
1200 Main Street W. McMaster University Faculty of Health Sciences,
Hamilton, Ontario, Canada L8N 3Z5.
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Postlicensure Safety Surveillance for Varicella Vac-
cine. Wise RP,* Salive ME, Braun MM, Mootrey GT,
Seward JF, Rider LG, Krause PR. JAMA 2000;284:1271–
1279.
S
INCE ITS LICENSURE IN 1995, THE EXTENSIVE USE OF
varicella vaccine and close surveillance of the associ-
ated anecdotal reports of suspected adverse effects provide
the opportunity to detect potential risks not observed
before licensure because of the relatively small sample size
and other limitations of clinical trials. The authors per-
formed a postlicensure case-series study of suspected vac-
cine adverse events reported to the US Vaccine Adverse
Event Reporting System (VAERS) from March 17, 1995,
through July 25, 1998. VAERS received 6574 case reports
of adverse events in recipients of varicella vaccine, a rate
of 67.5 reports per 100,000 doses sold. Approximately 4%
of reports described serious adverse events, including 14
deaths. The most frequently reported adverse events were
rashes, possible vaccine failures, and injection site reac-
tions. Misinterpretation of varicella serology after vaccina-
tion appeared to account for 17% of reports of possible
vaccine failures. Among 251 patients with herpes zoster,
14 had the vaccine strain of varicella zoster virus (VZV),
while 12 had the wild-type virus. None of 30 anaphylaxis
cases was fatal. An immunodeficient patient with pneu-
monia had the vaccine strain of VZV in a lung biopsy.
Pregnant women occasionally received varicella vaccine
through confusion with varicella zoster immunoglobulin.
Although the role of varicella vaccine remained unproven
in most serious adverse event reports, there were a few
positive rechallenge reports and consistency of many cases
with syndromes recognized as complications of natural
varicella. The authors conclude that most of the reported
adverse events associated with varicella vaccine are minor,
and serious risks appear to be rare. They could not confirm
a vaccine etiology for most of the reported serious events;
several will require further study to clarify whether vari-
cella vaccine plays a role. Education is needed to ensure
appropriate use of varicella serologic assays and to elimi-
nate confusion between varicella vaccine and varicella
zoster immunoglobulin.—Thomas J. Liesegang.
*1401 Rockville Pike, FDA CBER HFM-225, Rockville, MD 20852-
1448. E-mail: rpwise@cber.fda.gov
●
Long-term results of pneumatic retinopexy. Eter N,*
Boker T, Spitznas M. Graefes Arch Clin Exp Ophthalmol
2000;238:677– 681.
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