Evidence based medicineBy dr. Balgis MSc. CM FM.The science of
medicine is continuously changing if we do not adapt to this
change, the following might happen a. !e may have not give our
patient effective treatmentsb. !e may have wasted precious
resources."ld model of decision ma#ing$ The traditional model of
medical education depended on learning collection facts, principles
and rules of thumbs that would serve individual for a professional
life.$ The method passive dissemination of information %didactic
lecture in large session halls&$ The ' (rofessor) or the '
E*pert) become the standard source of information for decision
ma#ing$ (roblem can be answered by as#ing colleagues and local
e*pert, reading te*t boo#s % out of date by the time they are
published&, or browsing +ournals %but which +ournal should you
loo# at&,ew model of medical decision ma#ingThere is now a
strong trend towards the view that medical education should be
lifelong, oriented towards problem solving and based on the
principle that-. Clinical e*perience is important but observations
must be recorded systematically and without bias.. /egular
reference must be made to original literature0. The results of
studies must be critically e*amined using rules of evidence before
applying it to practiceMeaning of EBM according to others$
E*perience1based medicine1 the oldest ones are the most valid$
Elo2uenc1based medicine1 the loudestvoice is the most
heardEvidence-Based Medicine Evidence-Based Medicine
DefinitionDefinitionthe conscientious, the conscientious, explicit
and judicious explicit and judicious use of current best use of
current best evidence in making evidence in making decisions about
the decisions about the care of the individual care of the
individual patientpatient
the conscientious, the conscientious, explicit and judicious
explicit and judicious use of current best use of current best
evidence in making evidence in making decisions about the decisions
about the care of the individual care of the individual
patientpatient
The practice of EBM requires the integration of The practice of
EBM requires the integration of individual clinical
expertiseindividual clinical expertise and patient values and
patient values ith the ith the best available external clinical
evidencebest available external clinical evidence from from
s!stematic researchs!stematic research" "
The practice of EBM requires the integration of The practice of
EBM requires the integration of individual clinical
expertiseindividual clinical expertise and patient values and
patient values ith the ith the best available external clinical
evidencebest available external clinical evidence from from
s!stematic researchs!stematic research" "
Patients Needs/PreferencesClinical ExperienceBest Clinical
Evidence!hat evidence1based medicine is3$ 4ood doctors use both
individual clinical e*pertise and the best available e*ternal
evidence, and neither alone is enough. 5!ithout the former,
practice ris#s becoming evidence1tyrannised, for even e*cellent
e*ternal evidence may be inapplicable or inappropriate for an
individual patient.5 !ithout the latter, practice ris#s becoming
rapidly out of date, to the detriment of patients and
patient1care.Evidence based medicine$ EBM was developed in canada
to teach medical students but was latter applied to solving
clinical problem$ The aim of EBM is to encourage the use of
diagnostic test and therapeutic interventions that are proven to be
accurate, effective and safe in clinical research.$ EBM fits with
recommendations to ma#e undergraduate and postgraduate medical
education curriculum more problem centered, directed toward
lifelong learning and less about memori6ing a static body of
#nowledge.Evidence1based medicine is not 'coo#1boo#) medicine3$
(atients cannot go through a 7treatment tunnel8 assuming the same
management is appropriate and the same outcomes important to each$
E*ternal clinical evidence can inform, but can never replace,
individual clinical e*pertise $ 9our clinical accumen decides
whether the e*ternal evidence applies to the individual patient at
all and, if so, how it should be integrated into a clinical
decision.Evidence1based medicine is not 'cost1cutting) medicine3$
The aim is to give most benefit to each individual patient$ To
apply the most efficacious interventions which will ma*imise their
function, 2uality, and 2uantity of life$may raise rather than lower
the cost of their care.EBM is neither old1hat nor impossible to
practice3$ The former argument falls before the evidence35of
stri#ing variations in the integration of patient values into our
clinical behaviour5 of stri#ing variations in the rates with which
clinicians provide interventions of established benefit and
uselessness to their patients.5 in the inability of clinicians to
#eep abreast of important medical advances reported in primary
+ournalsThe patient 1. Start with the patient -- a clinical problem
or question arises out of the care of the patient The question 2.
Construct a well built clinical question derived from the caseand
classify it into one categoryThe resource 3. Select the appropriate
resources! and conduct a searchThe evaluation ". #ppraise that
evidence for its validity closeness to the truth! and applicability
usefulness in clinical practice!The patient $. %eturn to the
patient & 'a(e a clinical dicesion to apply or not to apply the
result of the study )integrate that evidence with clinical
e*pertise+ patient factors to carry out the dicesionSelf-evaluation
,. -valuate your performance with this patientWhat is
Evidence-based What is Evidence-based PracticePracticeClinical
Skills Keepingup to dateClinical questionudit!ind the Evidenceppl"
to PracticeCritical ppraisalTypes of :uestions#herap"$prevention
%uestionPrognosis %uestion question concerning the effectiveness of
a treat&ent or preventative &easure question concerning
outco&e of patient 'ith a particular conditionDiagnosis
%uestion(ar& %uestion question concerning the abilit" of a test
to predict the likelihood of a disease question concerning the
likelihood of a therapeutic intervention to cause har&Type of
Question Type of Question Suggested best type of Study Suggested
best type of Study#herap" #herap" )C#*cohort * case control * case
series )C#*cohort * case control * case seriesDiagnosis Diagnosis
Prospective+ blind co&parison to a gold standard Prospective+
blind co&parison to a gold standardEtiolog"$(ar&
Etiolog"$(ar& )C# * cohort * case control * case series )C# *
cohort * case control * case seriesPrognosis Prognosis Cohort stud"
* case control * case series Cohort stud" * case control * case
seriesPrevention Prevention )C#*cohort stud" * case control * case
series )C#*cohort stud" * case control * case seriesClinical
E,a& Clinical E,a& Prospective+ blind co&parison to
gold standard Prospective+ blind co&parison to gold
standardCost Cost Econo&ic anal"sis Econo&ic anal"sisTypes
of Research StudiesTypes of Research StudiesCertain study designs
are superior to others Certain study designs are superior to others
when answering particular questions. when answering particular
questions. RCT are considered the best for addressingRCT are
considered the best for addressing questions about
therapy.questions about therapy. Etiology questions may be
addressed by case-controlEtiology questions may be addressed by
case-control & cohort studies. & cohort studies.ther
aspects rele!ant to study design include ther aspects rele!ant to
study design include placebo comparison group and follow-up.
placebo comparison group and follow-up. Evidence
P"ra&idEvidence P"ra&idMeta-nal"sisMeta-nal"sis
S"ste&atic )evie'S"ste&atic )evie' )ando&i-ed
Controlled #rial)ando&i-ed Controlled #rial Cohort
studiesCohort studies Case Control studiesCase Control studies Case
Series$Case )eportsCase Series$Case )eports ni&al research
ni&al research#his is often referred to as the . #his is often
referred to as the .evidence p"ra&id evidence p"ra&id./ 0t
is./ 0t is used to illustrate the evolution of the literature/used
to illustrate the evolution of the literature/ #he base of the
p"ra&id is 'here infor&ation usuall"#he base of the
p"ra&id is 'here infor&ation usuall" starts 'ith an idea or
laborator" research/ s these ideasstarts 'ith an idea or laborator"
research/ s these ideas turn into drugs and diagnostic tools the"
are tested inturn into drugs and diagnostic tools the" are tested
in laboratories &odels+ then in ani&als+ and finall"
inlaboratories &odels+ then in ani&als+ and finall" in
hu&ans/ #he hu&an testing &a" begin 'ith
volunteershu&ans/ #he hu&an testing &a" begin 'ith
volunteers and go through several phases of clinical trials
beforeand go through several phases of clinical trials before the
drug or diagnostic tool can be authori-ed for usethe drug or
diagnostic tool can be authori-ed for use 'ithin the general
population/ )ando&i-ed controlled'ithin the general population/
)ando&i-ed controlled trials are then done to further test the
effectiveness andtrials are then done to further test the
effectiveness and efficac" of a drug or therap"/efficac" of a drug
or therap"/ As you move up theAs you move up the pyramid the amount
of available literaturepyramid the amount of available literature
decreases, but increases in its relevance to thedecreases, but
increases in its relevance to the clinical setting. clinical
setting. "eta-#nalysis"eta-#nalysis takes the s"ste&atic revie'
1see takes the s"ste&atic revie' 1see belo'2 a step further b"
using statistical belo'2 a step further b" using statistical
techniques to co&bine the results of several techniques to
co&bine the results of several studies as if the" 'ere one
large stud"/ studies as if the" 'ere one large stud"/ Systematic
Re!iewsSystematic Re!iews usuall" focus on a clinical usuall" focus
on a clinical topic and ans'er a specific question/ E,tensive topic
and ans'er a specific question/ E,tensive literature searches are
conducted to identif" literature searches are conducted to identif"
studies 'ith sound ðodolog"/ #he studies are studies 'ith
sound ðodolog"/ #he studies are revie'ed+ assessed+ and
su&&ari-ed according revie'ed+ assessed+ and
su&&ari-ed according to the predeter&ined criteria of
the revie' to the predeter&ined criteria of the revie'
question/question/Randomi$ed Controlled TrialsRandomi$ed Controlled
Trials are carefull" are carefull" planned pro3ects that stud" the
effect of a planned pro3ects that stud" the effect of a therap" or
test on real patients/ #he" include therap" or test on real
patients/ #he" include ðodologies that reduce the potential
for ðodologies that reduce the potential for bias and that
allo' for co&parison bet'een bias and that allo' for
co&parison bet'een intervention groups and control groups 1no
intervention groups and control groups 1no intervention2/ Evidence
for questions of intervention2/ Evidence for questions of diagnosis
is found in prospective trials 'hich diagnosis is found in
prospective trials 'hich co&pare tests 'ith a reference or
.gold co&pare tests 'ith a reference or .gold standard. test/
standard. test/ Randomi$ed Controlled Trial %RCT&Randomi$ed
Controlled Trial %RCT&Cohort studyCohort studyCohort Studies
Cohort Studies take a large population and follo' patientstake a
large population and follo' patients 'ho have a specific condition
or receive a particular'ho have a specific condition or receive a
particular treat&ent over ti&e and co&pare the&
'ith another grouptreat&ent over ti&e and co&pare
the& 'ith another group that is si&ilar but has not been
affected b" the conditionthat is si&ilar but has not been
affected b" the condition being studied/being studied/ #nswers
prognosis' etiology' pre!ention questions #nswers prognosis'
etiology' pre!ention questionsCohorts are defined populations that'
as a whole' areCohorts are defined populations that' as a whole'
are followed in an attempt to determine distinguishingfollowed in
an attempt to determine distinguishing subgroup
characteristics.subgroup characteristics. Researchers identify and
compare two groups o!er aResearchers identify and compare two
groups o!er a period of time. period of time.#t the start of the
study' one of the groups has a#t the start of the study' one of the
groups has a particular condition or recei!es a particular
treatment'particular condition or recei!es a particular treatment'
and the other does not. and the other does not.#t the end of a
certain amount of time' researchers#t the end of a certain amount
of time' researchers compare the two groups to see how they did.
compare the two groups to see how they did.Case Control studyCase
Control studyns'ers prognosis+ etiolog"+ prevention ns'ers
prognosis+ etiolog"+ prevention questionsquestions0dentifies
patients 'ho alread" have the 0dentifies patients 'ho alread" have
the outco&e of interest and control patients 'ithout
outco&e of interest and control patients 'ithout that
outco&e+ and look back to see if the" had that outco&e+ and
look back to see if the" had the e,posure of interest or notthe
e,posure of interest or not// #hese t"pes of studies are often less
reliable #hese t"pes of studies are often less reliable than
rando&i-ed controlled trials and cohort than rando&i-ed
controlled trials and cohort studies because sho'ing a statistical
studies because sho'ing a statistical relationship does not
&ean than one factor relationship does not &ean than one
factor necessaril" caused the other/necessaril" caused the other/
Case series & Case ReportsCase series & Case Reports Case
SeriesCase Series consist of collections of reports consist of
collections of reports on the treat&ent of individual patients/
on the treat&ent of individual patients/ Case ReportCase Report
is a report on a single patient/ is a report on a single patient/
Because the" are reports of cases and use Because the" are reports
of cases and use no control groups 'ith 'hich to co&pare no
control groups 'ith 'hich to co&pare outco&es+ the" have no
statistical validit" / outco&es+ the" have no statistical
validit" / ns'ers prognosis+ etiolog"+ prevention ns'ers prognosis+
etiolog"+ prevention questionsquestionsPractice 4uidelinesPractice
4uidelines(ractice )uidelines (ractice )uidelines are
s"ste&aticall" developedare s"ste&aticall" developed
state&ents to assist practitioner and patient
&akestate&ents to assist practitioner and patient &ake
decisions about appropriate health care for specificdecisions about
appropriate health care for specific clinical circu&stances/
4uidelines revie' and evaluateclinical circu&stances/
4uidelines revie' and evaluate the evidence and then &ake
e,plicit reco&&endationsthe evidence and then &ake
e,plicit reco&&endations for practice/for practice/ #he
p"ra&id serves as a guideline to the hierarch" of#he
p"ra&id serves as a guideline to the hierarch" of evidence
available/ 5ou &a" not al'a"s find the bestevidence available/
5ou &a" not al'a"s find the best level of evidence to ans'er
"our question/ 0n thelevel of evidence to ans'er "our question/ 0n
the absence of the best evidence+ "ou then need to considerabsence
of the best evidence+ "ou then need to consider &oving do'n the
p"ra&id to other t"pes of studies/ &oving do'n the
p"ra&id to other t"pes of studies/;evels of Evidence$ ;evel
-3/andomi6ed Clinical Trials$ ;evel .3DD +ournal derived from ED
countries around the world and E>F of the articles are in
english.$ @t also contains E million references since -GHH to
-GG=.From the guru of EBM 17MEC;@,E is the best general source of
current best evidence at present because of its breadth and
constant maintenance.Thus, it is important to evidence1based
practice that clinicians develop and hone MEC;@,E searching s#ills
and ac2uire local access.8Evidence1based Medicine3 how to practice
I teach EBM 1 Sac#ett C ; et al-GGJClinical scenario$ (atients
usually come in to the clinic for problems. Anfortunately these
problem are vague and sometimes not clearly stated. $ To state the
problem clearly, you must bear in mind that there are only three
important elements that the patient want to #now-. !hat their
disease are.. !hat treatment they should be given0. !hat is the
result to e*pectBefore attempting to Before attempting to search
for the search for the evidence in the evidence in the literature,
construct literature, construct a well-built or clearly a
well-built or clearly structured question structured question that
could be broken that could be broken into the following into the
following four partsfour partsBefore attempting to Before
attempting to search for the search for the evidence in the
evidence in the literature, construct literature, construct a
well-built or clearly a well-built or clearly structured question
structured question that could be broken that could be broken into
the following into the following four partsfour partsThree
important elements in clinical research are baically$PIO
analysis):$ P - Patient/Population$ I-Intervention$ O -
Outcome$PICO analysis):$ P - Patient/Population$ I-Intervention$ C
Comparison$ O - OutcomeSome time the researcher can add
Method((1)1) ((atient * atient * ((opulationopulation What is the
primary problem, What is the primary problem, disease or
co-existing conditions?disease or co-existing conditions?On what
groups do you want On what groups do you want information?
information? How would you describe a group of How would you
describe a group of patients similar to the one in patients similar
to the one in question? question? Sometimes age or sex of a patient
Sometimes age or sex of a patient may be relevant and should be may
be relevant and should be includedincluded#!xample" post-menopausal
women !xample" post-menopausal women with hypertensionwith
hypertension%+& Intervention ,hat medical e!ent do you want to
study the effect of- ,hich main inter!ention are you considering'
prescribing a drug' ordering a test' ordering surgery-. . . .
%.& Comparison Compared to what- /etter or worse than no
inter!ention at all or than another inter!ention- ,hat is the main
alternati!e to compare with the inter!ention' are you trying to
decide between two drugs' a drug and a placebo' or two diagnostic
tests-Sometimes there is no comparison. %0& Outcome ,hat is the
effect of the inter!ention-,hat do you hope to accomplish' measure'
impro!e' or affect with this inter!ention- ,hat are you trying to
do for the patient' relie!e or eliminate the symptoms' reduce side
effects' reduce cost- .. .6 E1ample2 impro!e quality of life What
&akes a clinical question What &akes a clinical question
'ell built7'ell built7$uestion should be directl!$uestion should be
directl! relevant to the problem at hand" relevant to the problem
at hand" $uestion should be phrased to$uestion should be phrased to
facilitate searching for a precisefacilitate searching for a
precise anser" anser"Asking a well-built question, likeAsking a
well-built question, like many clinical skills, needs practice.many
clinical skills, needs practice. %fter constructing the &'()
%fter constructing the &'() anal!sis, determine the categor!
anal!sis, determine the categor! of the question"of the
question"There are the four categories of There are the four
categories of EBM questionsEBM questionsCategories of EBM
Categories of EBM %uestions%uestionsSolves questions about which
Solves questions about which treatment to administer, and what
treatment to administer, and what might be the outcome of different
might be the outcome of different treatment optionstreatment
options#or most therapy questions one may #or most therapy
questions one may want to loo$ for the best evidence want to loo$
for the best evidence namely a randomi%ed controlled study, namely
a randomi%ed controlled study, and if the study can be a double
blind, and if the study can be a double blind, so much the betterso
much the better
- !xample" find the evidence for the use of - !xample" find the
evidence for the use of
anticoagulants in patients with atrial anticoagulants in
patients with atrial fibrillationfibrillationSolves questions about
which Solves questions about which treatment to administer, and
what treatment to administer, and what might be the outcome of
different might be the outcome of different treatment
optionstreatment options#or most therapy questions one may #or most
therapy questions one may want to loo$ for the best evidence want
to loo$ for the best evidence namely a randomi%ed controlled study,
namely a randomi%ed controlled study, and if the study can be a
double blind, and if the study can be a double blind, so much the
betterso much the better
- !xample" find the evidence for the use of - !xample" find the
evidence for the use of
anticoagulants in patients with atrial anticoagulants in
patients with atrial fibrillationfibrillation3& Therapy3&
TherapySolves questions about degree to which aSolves questions
about degree to which a test is reliable and clinically useful,
totest is reliable and clinically useful, to decide whether the
patient would benefitdecide whether the patient would benefit from
itfrom it &ost articles compare result of a certain&ost
articles compare result of a certain diagnostic test with that of a
standarddiagnostic test with that of a standard test regarded as
being a 'gold standard' test regarded as being a 'gold standard'-
!xample" search for the best diagnostic- !xample" search for the
best diagnostic test for (l%heimer)s disease test for (l%heimer)s
disease+& 4iagnosis+& 4iagnosisSolves problems Solves
problems about the relationship about the relationship between a
disease between a disease and a possible cause and a possible
cause
- - !xample" find out if a diet !xample" find out if a diet rich
in saturated fats rich in saturated fats increases the ris$ of
heart increases the ris$ of heart disease, and if so by how
disease, and if so by how muchmuchSolves problems Solves problems
about the relationship about the relationship between a disease
between a disease and a possible cause and a possible cause
- - !xample" find out if a diet !xample" find out if a diet rich
in saturated fats rich in saturated fats increases the ris$ of
heart increases the ris$ of heart disease, and if so by how
disease, and if so by how muchmuch.& Etiology.&
Etiology(nswers questions about a patient)s (nswers questions about
a patient)s future health, life span and quality of future health,
life span and quality of life in the event one chooses a life in
the event one chooses a particular treatment option particular
treatment option -!xample" find how would the quality of-!xample"
find how would the quality of life change for a patient who
undergoeslife change for a patient who undergoes surgery for
prostate cancersurgery for prostate cancer The next step would be
to determine theThe next step would be to determine the best study
design needed to answer thebest study design needed to answer the
clinical question. clinical question.0& (rognosis0&
(rognosisThe Boolean (rinciple$ The venn diagram depicts 0
sets$!hich are designated as set?, set B, set C $ Each set has
contents which are referred to elements$ The element consist of
some numbers.$ ,ote that the different sets haveoverlapping
elements$ Boolean logic can be used to e*press the relationships
between the various sets in this diagram, or to identify specific
elements.$ This achieved using connectives )?,C)or '"/). The union
between set ? and Set B can be e*pressed in Boolean logic as ? "/
Bin the diagram, this would be represented by elements -,.,0,=,>
and HB"";E?, ;"4@C?,C K "/ K ,"T$ "/HEART DISEASESHYPERTENSION"/ is
M"/E$ The union between set ? and Set B can be e*pressed in Boolean
logic as ? "/ Bin the diagram, this would be represented by
elements -,.,0,=,> and HB"";E?, ;"4@C$ ?,CHEART
DISEASESHYPERTENSIONAND.. The @ntersect of sets ? and B can be
e*preseed as? ?,C B in the diagram, this would be repsented by
elements . and 0. ,ote that unions K "/ tend to incease the number
of elements included, while @ntersects K ?,C tend to do the
opposite$ To ma#e things more e*citing, brac#ets '%&) can help
us use unions and intersects in the same e*pressionfor e*ample3 % ?
?,C B& "/ C would refer to elements .,0,=,H and E but the
similar e*pressions ? ?,C %B "/ C& would refer to elements .,0,
and =. B"";E?, ;"4@C$
,"THEARTDISEASESNotCONGENITALHEARTDISEASES;imits$ ;ocal holdings
%for library only&$ ?ge groups$ (ublication types$ ;anguage$
9ear of publication$ . /andomi6ed controlled trialH.DGJH. N= ?,C
N> -.@ scanned the titles and come up with one study to read and
confident that this study is the most recent, up todate and
relevant@n searching through medline there are several general
stepsSTE( @1 develop an initial search strategy using a single disc
Step @ ?. phrase the 2uestion as precisely as possible -. The #ind
of patient will be perform % specified as a disease entity&..
@ntervention being evaluated % a drug, a diagnostic test, an
operative procedure& 0. The outcomes of interest to the
researcher % mortality, morbidity, 2uality of life&=. @f needed
we can add methodological filter$ STE( @ B 5 @dentify #ey concepts
in the 2uestion phrase$ ?t least one of #ey concept should be
specified in sufficient detail for a meaningful search to be
conducted$ STE( @ C1 Broaden each #ey concepts , to account for
differences in use of terminology$ @n preparing to search a
database for the #ey concepts that one identifies, a ma+or
difficulty to be addresed is the problem of non1uniform medical
terminology.$ This problem can be solved in two ways3-. Asing a
free te*t search % cancer or new growth or neoplasm or tumor&..
Asing a medical sub+ect heading % MeS
