critical appraisal to treatment
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Putu Moda Arsana
FKUB, Malang,2012
CRITICAL APPRAISAL TOTREATMENT STUDY
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BASIC CONCEPT
Applicable
Important
Validity
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VALIDITY
Was the assignment of patients to treatments randomized?randomized--
Was follow-up of patients sufficiently long and complete?follow up--
Was the randomization list concealed?concealed-- Were all patients analyzed in the groups to which they were randomized?
Were patients, clinicians, and study personnel kept blind to treatment?
Were the groups treated equally, apart from the experimental treatment?
Were the groups similar at the start of the trial apart from the experimentaltherapy?
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IMPORTANT
What is the magnitude of the treatment
effect?
How precise is the estimate of the
treatment effect?
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Applicability:Can you apply this valid, important evidence about
therapy in caring for your patient?
Do these results apply to our patient?
Is our patient so different from those in thestudy that its results cannot apply?
Is the treatment feasible in our setting?
What are our patients potential benefits and harms from the therapy?
Method I: f Risk of the outcome in our patient,relative to patients in the trial.Expressed as a decimal:______NNT/f=______/______=______(NNT for patients like ours)
Method II: 1/(PEERRRR) Our patients expected event rate if theyreceived the control treatment (PEER)=______1/(PEERRRR)=1/________=______(NNT for patients like ours)
Are our patients values and preferences satisfied by the regimen and its consequences?
Do we and our patient have a clear assessmentof their values and preferences?
Are they met by this regimen and its
consequences?
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IMPORTANT
Occurrence of diabeticneuropathy at 5 years among
insulin-dependent diabetics in
the DCCT trial
Relative riskreduction
(RRR)
Absolute riskreduction
(ARR)
Numberneeded to treat
(NNT)
Usual insulin
regimen controlevent rate
(CER)
Intensive insulin
regimenexperimental
event rate (EER)
CEREER
CER
CEREER 1/ARR
9.6% 2.8% 9.6%2.8%
9.6%
=71%
9.6%2.8%
=6.8%
1/6.8%
=15 patients
Result in population 95% CI 4.4% to 9.2% 11 to 23
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RUMUS CI 95% ON ARR
CER 1 CER EER 1 EER 1.96
number of control patients number of experimental patients
0.96 0.904 0.028 0.9721.96
730 711
2.4%
Jadi ARR pada populasi = 6.8% 2.4% = 4.4% - 9.2%.
NNT pada populasi = 1 : ARR populasi = 11 23 pasien
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A 65-year-old man is seen in our office after being
discharged from hospital 2 weeks previously. During thisadmission he suffered a transient ischemic attack (TIA),
and being diagnosed with carotid stenosis. His hospital
stay was uncomplicated and his discharged medications
included metoprolol50 mg BID for hypertension andaspirin 81 mg daily. Today, he brought us an article from
the internet describing the benefits of statinsfor stroke
prevention and he wonders what this medication is and if
he should take it. Our note from his last visit showed that
his TC was 5.0 mmol/L, HDL-C was 2.0 mmol/L, and
LDL-C was 2.0 mmol/L.
His examination was unremarkable
(Strauss SE, et.al.Therapy in: Evidence-Based Medicine, 2005)
CLINICAL SCENARIO (modif ied)
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STEPS
Ask a foreground question
Acquire some articles
Appraise the evidence
Apply the findings
Assess your performance
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GOOD CLINICAL TRIAL
VALID
IMPORTANT APPLICABLE
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ARE THE STUDY VALID?
1. Was the assignment of Pxrandomized? Yes
2. Was follow-up sufficiently long & complete? Yes
3. Was all Pxanalyzed in groups?4. Were Px& Dr kept blind to Rx?
5. Were groups treated equally?
6. Were groups similar at start of study?
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Loss of follow up :
15+10=25
25/4731= 0.53%
Intention to treat analysis
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Clinical trials:a, b, c are accounted as failure of Exp arm
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WHAT IS MEANT BY INTENTION TO TREATANALYSIS? SURVEY OF PUBLISHEDRANDOMIZED CONTROLLED TRIALS
(Hollis S, Campbell F. BMJ 1999; 319: 670 -4)
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ARE THE STUDY VALID?
1.Was the assignment of Pxrandomized? Yes
2. Was follow-up sufficiently long & complete? Yes
3. Was all Px analyzed in groups? Yes4. Were Px& Dr kept blind to Rx?
5.Were groups treated equally?
6. Were groups similar at start of study?
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ARE THE STUDY VALID?
1.Was the assignment of Pxrandomized? Yes
2. Was follow-up sufficiently long & complete? Yes
3. Was all Pxanalyzed in groups? Yes
4. Were Px& Dr kept blind to Rx? Yes
5.Were groups treated equally?
6. Were groups similar at start of study?
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Are the study valid?
1.Was the assignment of Pxrandomized? Yes
2. Was follow-up sufficiently long & complete? Yes
3. Was all Pxanalyzed in groups? Yes
4. Were Px& Dr kept blind to Rx? Yes
5.Were groups treated equally? Yes
6. Were groups similar at start of study?
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Is SPARCL Study valid?
Yes this is valid !
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ARE THE VALID RESULTS OFTHE STUDY IMPORTANT?
1.What is the magnitude of R/ effect?
2.How precise is this estimate of R/ effect?
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IMPORTANCE
1. MAGNITUDE OF THE TREATMENT P value
Relative Risk Reduction (RRR)
Relative Risk Increase (RRR)
Absolute Risk Reduction (ARR) Absolute Risk Increase (ARI)
Number Needed to Treat (NNT)
Number Needed to Harm (NNH)
2. HOW PRECISE IS THE TREAMENT EFFECT?
Construct Confidence Interval (CI)
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NNT = number needed to treat= number of patients should be treated to
avoid 1 bad outcome avoid outcome= number of patients should be treated to
have 1 additional outcome have outcome
NNH = number needed to harm= number needed to harm one more patient
from the therapy
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ABSOLUTE RISK REDUCTION PRIMARYOUTCOME ON FATAL OR NON FATAL STROKE
ABSOLUTE RISK REDUCTION (ARR) : 13.1-11.2 = 1.9
NNT = 1/ARR X 100% = 100/1.9 ~ 52.6 ~ 53
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ABSOLUTE RISK INCREASE (ARI) ONHEMORRHAGIC STROKE (HS)
Atorvaevent rate (HS) : 55/2365 X 100%= 2.32%
Placebo event rate (HS) : 33/2366 X 100%= 1.4%
ARI HS : 2.32%-1.4% = 0.92 %
Number Needed to Harm (NNH) :
1/ARI X 100% = 1/0.92 x 100%= 108
Note: kejadianHS padaatorvaada55 pasiendari2365 pasien group
atorvasedangkanpadaplasebosebanyak33 dari2366 pasien group
plasebo---l hal554
LHH (LIKELIHOOD OF BEING HELP VERSUS HARMED)
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LHH (LIKELIHOOD OF BEING HELP VERSUS HARMED)
IN REGARDS HEMORRHAGIC STROKE VSPRIMARY
OUTCOME (NON FATAL OR FATAL STROKE)
LHH = (1/NNT) vs (1/NNH)
1/53 vs 1/108
2.03 times
ARTINYA: kecenderungan untuk memberikan atorvastatin
benefitnya dua kali lebih baik dibandingkan dengan hanya
memberikan plasebo
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EBM Study Group
Is the results of SPARCL study
important?
Yes this is important!
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HOW TO SOLVE CONFOUNDING FACTORS?
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IS THERE ANY HIGHER
EVIDENCES?
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