University of Toronto Medical Journal, May 1999

72 Pages·1999·7.9 MB·English

by  Medical Society of the University of Toronto

University of Toronto Medical Journal
VOLUME 76, NUMBER 3 / MAY 1999
152 Bed Use on a Maltese Medical Ward: Implications for
UTMJ FOCUS SERIES: Evidence-Based Medicine
the Treatment of the Complications of Diabetes
140 Glossary Ann Bugeja, and Joseph Azzopardi
Evette Weil
158 An Introduction to Transcranial Magnetic Stimulation
142 Evidence-Based Medicine: Part 1 and Its Use in the Investigation and Treatment of
Defining Evidence-Based Medicine
Depression
Sean Wharton
Dan Mozeg, and Edred Flak
144 Evidence-Based Medicine: Part 2
164 NEWS AND VIEWS
From Clinical Trials to the Clinic
Evette Weil
179 MORNING REPORT
148 Evidence-Based Medicine: Part 3
Usefulness of Evidence-Based Medicine to Medical 183 CLINICOPATHOLOGICAL CORRELATION
Students and a Guide to the Use of Evidence-Based
Medicine 189 QUICK DIAGNOSIS
Mark Benaroia
194 TECHNOLOGY REVIEWS
150 Evidence-Based Medicine: Part 4
Making Sense of the Numbers
200 BOOK REVIEWS
The United Kingdom Prospective Diabetes Study
(UKPDS-38) - Treating Hypertensive Diabetic Patients
Sean Wharton
UTMJ Website Address: http://dante.med.utoronto.ca/utmj
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University of Toronto Medical Journal
Fdi'ndf.d In 1923 Voumi- 76, No. 3 Mav 1999
TABLE OF CONTENTS
UTMJ Focus Series News and Views
164 In the Literature: The UTMJ Club
Evidence-Based Medicine
140 Glossary
166 UTMJ Series on Complementary and Alternative
Evette Weil
Medicine (CAM) Part 3:
Homeopathy: Has it Beaten Medicine at its Own
142 Evidence-Based Medicine: Part 1
Game?
Defining Evidence-Based Medicine
Dan Perri
Sean Wharton
170 The Cuerrier Decision: Public Health and the
144 Evidence-Based Medicine: Part 2
Criminalization of HIV Serostatus Non-Disclosure
From Clinical Trials to the Clinic
Darrell Tan
Evette Weil
174 Keeping Doctors North: Recruiting and Retaining
148 Evidence-Based Medicine: Part 3
Physicians in Underserviced Areas
Usefulness of Evidence-Based Medicine to Medical
Jason A. Shack, and Alison D. Baker
Students and a Guide to the Use of Evidence-Based
Medicine
Morning Report
Mark Benaroia
179 The Dwindles
Ra Han, Mark Benaroia, and Barry J. Goldlist
150 Evidence-Based Medicine: Part 4
Making Sense of the Numbers
Clinicopathological Correlation
The United Kingdom Prospective Diabetes Study
183 Case of Confusion
(UKPDS - 38) - Treating Hypertensive Diabetic
Joanna Holland
Patients
Sean Wharton
Quick Diagnosis
189 Emergency Medicine Rounds
Public Health
Thomas Roger Harris, and Laura Catherine McAdam
152 Bed Use on a Maltese Medical Ward: Implications
for the Treatment of the Complications of Diabetes
Technology Reviews
Ann Bugeja, and Joseph Azzopardi
194 Robots Designed to Aid in Surgical Procedures
Martin Jugenburg
Neuropsychiatry
158 An Introduction to Transcranial Magnetic
Book Reviews
Stimulation and Its Use in the Investigation and
196 Stroke: Pathophysiology, Diagnosis, Management,
Treatment of Depression
Third Edition
Dan Mozeg, and Edred Flak
198 Clinical Neuroimmunology
200 The Massachusetts General Hospital Guide to
Psychiatry in Primary Care
Front cover illustration by Karen Petruccclli
Division of Biomedical Communications,
Department of Surgery, University of Toronto.
volume 76, number 3, May 1999 137
UTMJ
Editorial
Here is the third and final installment of Vol. 76 of the UTMJ. With Editors-In-Chiee
Sandra L. Demaries, MSc. (MD/PhD2)
this issue we close yet another chapter in the long and illustrious his¬
George Thanassoulis, BSc. (0T1)
tory of the Journal. We believe that this issue will provide, like so
many before, an enjoyable and thought provoking look at medical sci¬ Asst )C1ATI •; Editors
Richard Bitar, MSc. (0T1)
ence. Lets take a quick look at the pages of our final issue.
Julian Mathoo, MSc. (0T1)
In this issue we present two excellent original articles from very dif¬ Managing Editor
ferent areas of medicine. Mozcg et al. present a highly informative Phyllis Billia, Ph.D (0T1)
review on transcranial magnetic stimulation for the diagnosis and
Treasurer
treatment of depression. While Bugeja et al. have written a fascinat¬ Elaine Yeung, BA (0T1)
ing review on diabetes and ressource allocation. Moreover, in this
Art Director
focus issue on evidence based medicine, we have compiled a series of
Kevin Millar
short articles and a glossary of frequendy used terms that will intro¬
News & Views Editors
duce students to the sometimes complex but always important aspects
Andrew Lustig, BSc. (0T0)
of evidence based practice. We believe that this section will prove to
Sean Wharton, PharmD (0T1)
be a highly valuable learning tool that will continue in the years to
Quick Diagnosis Editors
come.
Thomas Harris, BSc. (0T1)
I aura McAdam, MSc. (0T1)
In addition, the News and Views section keeps our readers abreast of
CPC Editors
current events with two reviews of highly newsworthy stories. Tan
Jonathan Grynspan, BSc. (0T0)
has authored a report on the recent criminalization of HIV spread by
Joanna Holland, MSc. (0T1)
the supreme court. Baker and Shack have reviewed the important
Morning Report Editor
issue of physician underservicing in the North of Canada. Moreover,
Mark Benaroia, BSc. (0T1)
Morning Report presents the clinical reasoning behind a case of infec¬
Ra Han, Bsc. (0T0)
tive endocarditis whereas this issue’s discussion in Clinicopathological
Technology Review Editors
Correlation relates to an interesting case of dementia. We also con¬
Martin Jugenburg, BSc. (0T1)
tinue our series on complementary and alternative medicine which has
been a highlight of this year. Book Review Editor
Paul Giacomini, BSc. (0T1)
With this issue we mark the end of our tenure as editors of the
Website Directors
Journal. We have enjoyed this unique experience and are honored to Michael Szeto, BSc. (0T1)
have had the opportunity to be a part of a great tradition of the
Cops' Editors
Faculty of Medicine at the University of Toronto. However, we could
Raymond Fung, BSc. (0T1)
not have done this alone. We extend our deepest gratitude to our Adrian Harvey, MSc. (0T1)
associate editors who orchestrated the entire peer review process and
Secretary
to the many students and staff who patiently reviewed each submis¬
Joan Caverly
sion. Moreover, we thank the many section editors that have worked
Editorial Board
incredibly hard throughout the year to provide us with thought pro¬
Victoria Atkinson, BSc. (0T1)
voking and interesting articles. We are also indebted to the multi-tal¬
Dr. Andrew Baines, MD, FRCPC
ented illustrators whose contributions grace each cover and improve Gillian Edmonds, MSc. (0T1)
David Kaplan, MSc. (0T1)
the aesthetics of each article. We must also thank the many contrib¬
Michelle Lambert, MSc, (0T1)
utors whose works appeared in the pages of the Journal. Laslty, we
Dr. Robert Levitan, MD, FRCPC
are also very grateful for the continued support that we have received Eric Saettler, Ph.D (0T1)
Dr. Mladen Vranic, MD, DSc., FRCPC, FRSC
from our patrons and the Medical Society.
Biomedical Ci >mmunk:ations
Finally, we look to the future editors and their staff to continue the Zacharo Roula Drossis
long legacy of the l TMJ and uphold the high standards of this Monique Le Blanc
Kevin Millar
Journal. We are confident that they will prove to be successful.
Karen Petruccelli
Chesley Sheppard
Sincerely,
Design Consultant
Nancy Nowacek, MA
Sandra Demaries, MSc.
George Thanassoulis, BSc. TyPKSETTTING
Type & Graphics
Editors-in-Chief
138 University of Toronto Medical Journal
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volume 76, number 3, May 1999 139
Focus: Evidence-Based Medicine
Evidence-Based Medicine
Glossary
Evette Weil, BA (0T2)
Welcome to the UTMJ's Focus Series on evidence-based medicine.
This series of short articles is intended to serve as an introduction
to a critical area of modern medical practice. The editors wish to
thank Sean Wharton (0T1) for editing the series, and Dr. Andrew
Baines for critical review of the articles.
Evidcncc-based medicine utilizes a language of clinical epi¬
demiological terms. To understand and critically appraise
research articles, the physician must have a grasp of these con¬
cepts. The following glossary is provided as an introduction
and reference tool to be used in applying EBM principles to
the literature. The terms are adapted from a glossary published
online by the Evidence-Based Medicine Working Group at the
University of Alberta, (http://www.mcd.ualberta.ca/ebm/
ebm.htm)
Absolute risk
The observed or calculated probability of an event in the
population under study.
Absolute risk reduction (ARR)
The difference in the absolute risk (rates of adverse events)
between study and control populations.
Blinded study (Syn: masked study)
A study in which observer(s) and/or subjects are kept igno¬
rant of the group to which the subjects are assigned, as in
an experimental study, or of the population from which the
subjects come, as in a non-experimental or observational
study. Where both observer and subjects are kept ignorant,
the study is termed a double-blind study. If the statistical
analysis is also done in ignorance of the group to which
subjects belong, the study is sometimes described as triple
blind. The purpose of "blinding" is to eliminate sources of
bias. elli
c
c
u
Case-series Petr

n
Report of a number of cases of disease. are
K
140 University of Toronto Medical Journal
Case-control study determined by the sensitivity and specificity' of the test, and by
Retrospective comparison of exposures of persons with dis¬ the prevalence of the condition for which the test is used.
ease (cases) with those of persons without the disease.
Prevalence
Cohort study The proportion of persons with a particular disease within
Follow-up of exposed and non-exposed defined groups, a given population at a given time.
with a comparison of disease rates during the time covered.
Prospective study
Confidence interval (Cl) Study design where one or more groups (cohorts) of indi¬
The range of numerical values in which we can be confi¬ viduals who have not yet had the outcome event in ques¬
dent (to a computed probability, such as 90 or 95%) that tion are monitored for the number of such events that
the population value being estimated will be found. occur over time.
Confidence intervals indicate the strength of evidence;
where confidence intervals are wide, they indicate less pre¬ Randomized controlled trial
cise estimates of effect. Study design where treatments, interventions, or enrollment
into different study groups are assigned by random allocation
Incidence rather than by conscious decisions of clinicians or patients. If
The number of new cases of illness commencing, or of per¬ the sample size is large enough, this study design avoids prob¬
sons falling ill, during a specified time period in a given lems of bias and confounding variables by assuring that both
population. known and unknown determinants of outcome are evenly dis¬
tributed between treatment and control groups.
Intention to treat analysis
A method for data analysis in a randomized clinical trial in Relative risk (RR)
which individual outcomes are analyzed according to the The ratio of the probability of developing, in a specified
group to which they have been randomized, even if they period of time, an outcome among those receiving the treat¬
never received the treatment they were assigned. By simu¬ ment of interest or exposed to a risk factor, compared with
lating practical experience it provides a better measure of the probability of developing the outcome if the risk factor
effectiveness. or intervention is not present.
Likelihood ratio Relative risk reduction (RRR)
Ratio of the probability that a given diagnostic test result The extent to which a treatment reduces a risk, in compar¬
will be expected for a patient with the target disorder rather ison with patients not receiving the treatment of interest.
than for a patient without the disorder.
Retrospective study
Number Needed to Treat (NNT) Study design in which cases where individuals who had an
The number of patients who must be exposed to an inter¬ outcome event in question are collected and analyzed after
vention before the clinical outcome of interest occurred; for the outcomes have occurred.
example, the number of patients needed to treat to prevent
Sensitivity (of a diagnostic test)
one adverse outcome.
The proportion of truly diseased persons, as measured by
Odds the gold standard, who are identified as diseased by the test
A proportion in which the numerator contains the number under study.
of times an event occurs and the denominator includes the
Specificity (of a diagnostic test)
number of times the event does not occur.
The proportion of truly nondiseased persons, as measured
Odds Ratio (Syn: cross-product ratio, relative odds) by the gold standard, who are so identified by the diagnos¬
A measure of the degree of association; for example, the tic test under study.
odds of exposure among the cases compared with the odds
Validity
of exposure among the controls.
The extent to which a variable or intervention measures what
Predictive value it is supposed to measure or accomplishes what it is supposed
In screening and diagnostic tests, the probability that a per¬ to accomplish. The internal validity of a study refers to the
son with a positive test is a true positive (i.e., does have the integrity of the experimental design. The external validity of a
disease), or that a person with a negative test truly does not study refers to the appropriateness by which its results can be
have the disease. The predictive value of a screening test is applied to non-study patients or populations.
volume 76, number 3, May 1999 141
L such int rest and the principles underlying the practice cerns. The application of practice guidelines, pharmacoeco-
o' EBM, The UTMJ ardcle in this issue, by Evette Weil, nomic analysis, and cost-effectiveness studies is promoted
ad dresses the principles underlying the practice of EBM. by EBM.6 Clinician practicing EBM are sensitive to the eco¬
nomic environment and can make macro-decisions based
Reasons for the Interest in EBM on information from large populations rather than individ¬
The main reason for the increased interest in EBM is that ual cases.
it address three major problems in clinical practice; the
inability to manage large volumes of medical information, c) Optimizing Patient Care
the difficulty in containing rising medical costs, and the Most importantly, practicing patient-specific EBM will pro¬
desire to optimize patient care with current, up to date ther¬ vide each patient with the optimal level of care. Decisions
apeutic options. made regarding a patient’s medical management will be
based on a combination of best available evidence, clinical
a) Information Management judgement and expertise, cost effective therapies, and
Physicians are interested in learning how to practice EBM patient preference.1 Clinicians may argue that this approach
in an attempt to manage the vast amount of medical infor¬ has always been a part of patient management, yet EBM
mation that is now available. The need for new, clinically formalizes this process and provides the clinician with infor¬
relevant data is essential for a practice that strives to achieve mation that has been comprehensively reviewed by the lead¬
the optimal medical management of patients. Physicians are ers in the field.
sensitive to this issue, yet are incapable of processing the
volumes of information necessary to keep up to date. Self The practice of evidence based medicine is probably not a
reports from enthusiastic clinical teachers place their med¬ fad. Specific terminology may change over time but the
ical reading time at only 2 hours per week, yet general physi¬ concepts introduced with EBM will become more common
cians must read 19 original articles a day 365 days a year, if within medical practice as medical students begin to learn
they want to remain informed within their own field.3 This the benefits of this approach. Medical students and resi¬
expectation is obviously unattainable. Therefore physicians dents will follow the lead of opinion leaders, many that have
are constantly in search of rapid solutions to bring their pioneered the field of EBM, and will learn the benefits and
knowledge up to the level of recent advances. Continuing pitfalls of this approach.1-2’5’7’8 Hopefully, the methods of
medical education (CME) attempts to address this concern, EBM will assist in resolving the three problems areas with¬
yet research has demonstrated that CME is often ineffective in clinical practice, resulting in improved ability to access
at modifying clinical behaviors and at improving health out¬ and integrate new information, realize cost containment and
comes of patients.4 optimize patient care using the best evidence available.
EBM attempts to provide clinicians with the tools to devel¬
op their own methods of continuing education, especially in
situations that can be immediately applied to the patient. References
Altering clinical practice and improving patient care are 1. Haynes RB, Sackett DL, Gray JMA, Cook DJ, Guyatt GH. (1996).
Transferring evidence from research into practice: 1. The role of clinical
practical steps that are inherent in the EBM process. EBM
care research evidence in clinical decisions. 1 ividence-Based Medicine. 1 (7):196-
provides a method of condensing the volumes of informa¬ 197.
tion available into an applicable approach that reflects the 2. Sackctt DL Rosenborg WMC, Gray JA, Haynes RB, Richardson WS. BMJ.
(1996). 312:71-2.
best evidence. Development of a structured question from
3. Davidoff F, Haynes B, Sackett D, Smith R. (1995). Evidence based med¬
the clinical case, a focused search of the literature, critical icine. A new journal to help doctors identify the information they need.
appraisal and the use of systematic reviews, overviews and BMJ 310:1085-6.
4. Sibley )C, Sackctt DL, Neufeld VR, et at. (1982). A randomized trial of
guidelines are all methods employed in EBM to address the
continuing medical education. N linglJ Med 306:511-5.
difficulty in accessing medical information.5 5. Oxman AD, Sackett DL, Guyatt GH. (1993). Users Guides to the med¬
ical literature. I. How to get started. JAMA 270(17):2093-2095.
6. Laupacis A, Fenny D, Dctsky AS, Tugwell PX. Tentative guidelines for
b) Medical Cost Constraints
using clinical and economic evaluations revisited. CMAJ. 1993;18(6):927-
The economic climate of the 1990s has required politicians, 929.
patients, and physicians to assess the cost of medical care. 7. Detsky AS. (1995). Regional variations in medical care. N lingl J Med.
333(9):589-590.
The focus of maximizing the limited resources to provide
8. Guyatt GH, Rennie D. (1993). Users guide to the medical literature. JslMA
the best care is a national issue that continues to be of con¬
270(17):2096-2097.
cern to the majority of Canadians. EBM attempts to pro¬
vide clinicians with a broad perspective on health econom¬
ics, emphasizing best practices that improve the health of
patients in the most cost-effective manner. This method of
practice preserves scarce resources for future medical con¬
volume 76, number 3, May 1999 142
Focus: Evidence-Based Medicine
Evidence-Based Medicine
Series: Part 1
Defining Evidence-Based
Medicine
Sean Wharton, BScPhm, PharmD (0T1)
An Introduction to the Evidence-Based Medicine clinical expertise and patient preference can override
Series research evidence. Examples include a clinical decision not
Evidence based medicine (EBM) has rapidly become a pop¬ to operate on a patient who is too frail, although the evi¬
ular method of clinical practice among health care profes¬ dence indicates that surgery is the best option, or a patient
sionals. The UTMJ series on EBM will introduce readers preference not to take the medication that clinical circum¬
to the various aspects of this new paradigm. The first three stances and research indicate is best for her condition.1
articles in this series are presented in this issue and will dis¬
cuss the concepts behind the establishment of EBM, the
practical aspects of using this approach and the usefulness Clinical Expertise
of EBM for medical students. Future issues of the UTMJ
will feature articles from opinion leaders within the field of
EBM. These articles will address the controversies associ¬
ated with the implementation and acceptance of EBM. As
this series develops we hope that readers will gain insight
into EBM and will consider the importance of practicing
EBM in their medical careers.
Research Evidence Patient Preference
EBM is an approach to medical practice that has been ini¬
Adapted from Haynes et al. EBMJ 1996
tiated by a broad coalition of clinicians, researchers, educa¬
tors, and policy makers to accelerate and improve the appli¬
cation of evidence from sound clinical care research to
Figure 1. /\ model for evidence-based clinical decisions.
clinical practice.1 The editors of the Evidence Based
Medicine Journal have used the following definition of
EBM.
The interest in EBM has dramatically increased in the past
Definition five years. Noting the increase in EBM articles listed on
Evidence based medicine is the conscientious and judicious MEDLINE easily validates this point. A focused search on
use of current best evidence from clinical care research in MEDLINE using the key words “evidence based medicine”
the management of individual patients.2 produces no citations between the years of 1985 to 1990,
eight citations from 1991 to 1995, and a shocking 876 cita¬
EBM patient management incorporates three distinct com¬ tions from 1996 to 1999. Such a dramatically increased
ponents; clinical expertise, patient preference, and research interest in a new approach to medical practice should
evidence, (see Figure 1) This model addresses the point that inspire any astute clinician to investigate both the reasons
143 University of Toronto Medical Journal
Focus: Evidence-Based Medicine
Evidence-Based Medicine
Series: Part 2
From Clinical Trials to the Clinic
Evette Weil, BA (0T2)
The Rise of Evidence-Based Medicine become both more user-friendly and widely accessible
Evidence-based medicine (EBM) is a philosophy of medical through the internet. As database-searching capabilities have
practice that emphasizes the value of scientific evidence as improved, physicians are increasingly able to find exactly the
a basis for determining patient care. Evidence has long been information they need without sifting through excessive
an integral part of medicine, but this new discipline formal¬ amounts of extraneous information.
ly advocates “the conscientious, explicit and judicious use of
current best evidence in making decisions about the care of The second goal of EBM is to decrease the variability
individual patients.”1 This approach does not contend that between physicians in areas where certain practices are
scientific evidence is the only valid input into clinical deci¬ clearly associated with superior outcomes. This variance has
sions, but rather that the best available data should be incor¬ been well documented in a number of cases, including the
porated with clinical experience and common-sense to pro¬ prescription of beta-blockers following myocardial infarc¬
vide the highest standard of care. Traditionally, physicians tion, as well as the performance of common surgical pro¬
have based much of their clinical decision-making on pro¬ cedures such as peripheral revascularization and mastecto¬
fessional training, textbooks, personal experience and expert my.1-4 Much of this incongruity can be explained by the
opinions. The evidence-based medicine model seeks to pre¬ absence of evidence in clinical decision-making, with the
serve this conventional base of knowledge while supple¬ accessibility and utilization of clinical research lying at the
menting it with quantitative information from methodolog¬ crux of the question of practice variability. Both a change
ically sound studies. in physician attitude toward the value of clinical research in
everyday practice and an increased availability of relevant
A number of factors have contributed to the emergence of information are needed to reduce such discrepancies.
evidence-based medicine as a new paradigm of clinical prac¬
tice. These include the extraordinary volume of published The final goal of EBM is to minimize health care costs while
literature, variations in physicians’ practices, and increased maximizing health care benefits. We live in an era of intensi¬
economic pressure to contain health care spending. It has fying economic constraints on health care. As newer, more
been estimated that the average family physician would have expensive tests and therapies are introduced into practice, there
to read 19 articles per day everyday of the year to remain is an increasing need to determine the value of any innovation.
current on best medical practice.2 Even if the appropriate Concurrently, there is an increasing demand for quality and
i'; articles arc sele :ed, this magnitude of reading is an unre¬ sensitivity to individual patient preferences. These sometimes
alistic expectation tor the majority of physicians. Therefore, opposing forces have made it necessary to clearly and quanti¬
the tirst goal, of vidence-based medicine is to make the tatively understand the improvements offered by a novel diag¬
most relevant and influential information easily available to nostic test or treatment. Thus, evidence-based medicine goes
physicians. 1 his has largely been accomplished via electron¬ hand in hand with cost-benefit studies which tty to incorpo¬
ic databases, such as Medline and Cancerlit, which have rate efficacy, quality of life, and monetary costs.
144 University of Toronto Medical Journal