randomized controlled trials, systematic reviews and meta-analysis achilleas thoma, md, msc, frcs(c)...

Randomized Controlled Randomized Controlled Trials, Systematic Reviews Trials, Systematic Reviews

and Meta-analysisand Meta-analysis

Achilleas Thoma, MD, MSc, FRCS(C)Achilleas Thoma, MD, MSc, FRCS(C)

CORE Jun 11 2008CORE Jun 11 2008

Division of Plastic Surgery,

Departments of Surgery & Clinical Epidemiology and Biostatistics

McMaster University

Learning ObjectivesLearning Objectives

1.1. What a RCT and a Systematic Review What a RCT and a Systematic Review are.are.

2.2. Why we use them.Why we use them.

Clinical state, setting, and circumstances

Patient preferences and actions

Research evidence

Health care resources

Clinical Expertise

Clinical Expertise

Clinical Decisions

Evidence-based SurgeryEvidence-based Surgery

Definition:Definition:

• The conscientious, explicit, and The conscientious, explicit, and judicious use of judicious use of current best evidence current best evidence in making decisions about the care of in making decisions about the care of individual patientsindividual patients

LeveLeve

llTherapy/Prevention, Therapy/Prevention,

Aetiology/HarmAetiology/HarmPrognosisPrognosis DiagnosisDiagnosis Differential Differential

diagnosis/symptom diagnosis/symptom

prevalence studyprevalence study

Economic and decision Economic and decision

analysesanalyses

1a1a SR (with SR (with homogeneity*) of ) of

RCTs RCTs SR (with SR (with homogeneity*) of ) of

inception cohort studies; inception cohort studies; CDR† validated in different validated in different

populationspopulations

SR (with SR (with homogeneity*) of Level ) of Level

1 diagnostic studies; 1 diagnostic studies; CDR† with with

1b studies from different clinical 1b studies from different clinical

centrescentres

SR (with SR (with homogeneity*) of ) of

prospective cohort studies prospective cohort studies SR (with SR (with homogeneity*) of Level 1 ) of Level 1

economic studieseconomic studies

1b1b Individual RCT (with Individual RCT (with

narrow narrow Confidence Interval‡))

Individual inception cohort Individual inception cohort

study with study with >> 80% follow-up; 80% follow-up; CDR† validated in a single validated in a single

populationpopulation

Validating** cohort study with Validating** cohort study with good††† reference standards; or reference standards; or CDR† tested within one clinical tested within one clinical

centrecentre

Prospective cohort study with Prospective cohort study with

good follow-up****good follow-up****Analysis based on clinically sensible Analysis based on clinically sensible

costs or alternatives; systematic costs or alternatives; systematic

review(s) of the evidence; and review(s) of the evidence; and

including multi-way sensitivity including multi-way sensitivity

analysesanalyses

1c1c All or none§ All or none case-seriesAll or none case-series Absolute SpPins and SnNouts†† All or none case-seriesAll or none case-series Absolute better-value or worse-value Absolute better-value or worse-value

analysesanalyses


cohort studiescohort studiesSR (with SR (with homogeneity*) of ) of

either retrospective cohort either retrospective cohort

studies or untreated control studies or untreated control

groups in RCTsgroups in RCTs

SR (with SR (with homogeneity*) of Level ) of Level

>2 diagnostic studies>2 diagnostic studiesSR (with SR (with homogeneity*) of 2b ) of 2b

and better studiesand better studiesSR (with SR (with homogeneity*) of Level >2 ) of Level >2

economic studieseconomic studies

2b2b Individual cohort study Individual cohort study

(including low quality RCT; (including low quality RCT;

e.g., <80% follow-up)e.g., <80% follow-up)

Retrospective cohort study or Retrospective cohort study or

follow-up of untreated control follow-up of untreated control

patients in an RCT; Derivation patients in an RCT; Derivation

of of CDR† or validated on split- or validated on split-

sample§§§ onlysample§§§ only

Exploratory** cohort study with Exploratory** cohort study with good†††reference standards; reference standards; CDR† after derivation, or after derivation, or

validated only on split-sample§§§ validated only on split-sample§§§

or databasesor databases

Retrospective cohort study, or Retrospective cohort study, or

poor follow-uppoor follow-upAnalysis based on clinically sensible Analysis based on clinically sensible

costs or alternatives; limited review(s) costs or alternatives; limited review(s)

of the evidence, or single studies; and of the evidence, or single studies; and

including multi-way sensitivity including multi-way sensitivity

analysesanalyses

2c2c "Outcomes" Research; "Outcomes" Research;

Ecological studiesEcological studies"Outcomes" Research "Outcomes" Research Ecological studiesEcological studies Audit or outcomes researchAudit or outcomes research


case-control studiescase-control studiesSR (with SR (with homogeneity*) of 3b ) of 3b

and better studiesand better studiesSR (with SR (with homogeneity*) of 3b ) of 3b

and better studiesand better studiesSR (with SR (with homogeneity*) of 3b and ) of 3b and

better studiesbetter studies

3b3b Individual Case-Control Individual Case-Control

StudyStudyNon-consecutive study; or Non-consecutive study; or

without consistently applied without consistently applied

reference standardsreference standards

Non-consecutive cohort study, Non-consecutive cohort study,

or very limited populationor very limited populationAnalysis based on limited alternatives Analysis based on limited alternatives

or costs, poor quality estimates of or costs, poor quality estimates of

data, but including sensitivity data, but including sensitivity

analyses incorporating clinically analyses incorporating clinically

sensible variations.sensible variations.

44 Case-series (and Case-series (and poor quality cohort and case-control studies§§

))

Case-series (and Case-series (and poor quality prognostic cohort studies***

))

Case-control study, poor or non-Case-control study, poor or non-

independent reference standard independent reference standard Case-series or superseded Case-series or superseded

reference standardsreference standardsAnalysis with no sensitivity analysisAnalysis with no sensitivity analysis

55 Expert opinion without Expert opinion without

explicit critical appraisal, explicit critical appraisal,

or based on physiology, or based on physiology,

bench research or "first bench research or "first

principles"principles"

Expert opinion without explicit Expert opinion without explicit

critical appraisal, or based on critical appraisal, or based on

physiology, bench research or physiology, bench research or

"first principles""first principles"









Expert opinion without explicit critical Expert opinion without explicit critical

appraisal, or based on economic appraisal, or based on economic

theory or "first principles"theory or "first principles"

Hierarchy of EvidenceHierarchy of Evidence

Systematic Reviews of Randomized Controlled Trials (Meta-analysis)

Single Randomized Controlled Trial (RCT)

Systematic Review of Observational Studies Addressing Patient-Important Outcomes

Single Observational Study Addressing Patient-Important Outcomes

Physiologic Studies

Unsystematic Clinical Observations

Hierarchy of EvidenceHierarchy of Evidence

• A well-conducted systematic review or A well-conducted systematic review or meta-analysis of well executed meta-analysis of well executed randomized controlled trials provides randomized controlled trials provides the highest level of evidence to support the highest level of evidence to support an answer to a surgical questionan answer to a surgical question

Randomized Controlled Trial (RCT)Randomized Controlled Trial (RCT)


• An experiment in which individuals are An experiment in which individuals are randomly allocated to receive or not randomly allocated to receive or not receive an experimental preventative, receive an experimental preventative, therapeutic, or diagnostic procedure therapeutic, or diagnostic procedure and then followed to determine the and then followed to determine the effect of the intervention effect of the intervention

RCTs in Surgery RCTs in Surgery

• Most scientifically rigorous study design to Most scientifically rigorous study design to evaluate the effect of a new surgical evaluate the effect of a new surgical intervention intervention

• Offers the maximum protection against biasesOffers the maximum protection against biases

• Balances both known and unknown Balances both known and unknown prognostic factors across treatment groups prognostic factors across treatment groups

RCTs in SurgeryRCTs in Surgery

• Not all of the questions we face in Not all of the questions we face in surgery can be answered by the RCT surgery can be answered by the RCT designdesign

• Must consider the plausibility and Must consider the plausibility and feasibility of the research questionfeasibility of the research question

Plausibility Plausibility

• Is the question answerable or not?Is the question answerable or not?

For example:For example:

Population = congenitally absent ear childrenPopulation = congenitally absent ear children

Intervention = Nagata technique Intervention = Nagata technique

Comparative = “genetic engineering method” Comparative = “genetic engineering method”

Outcome = “new” earOutcome = “new” ear

What is the problem here?What is the problem here?

FeasibilityFeasibility• Can the study design we choose answer the Can the study design we choose answer the

research question? research question?

For Example:For Example:Population = cosmetic abdominoplasty Population = cosmetic abdominoplasty

patientspatientsIntervention = intermittent lower extremity Intervention = intermittent lower extremity

pumppumpComparative = low molecular heparin Comparative = low molecular heparin Outcome = prevention of fatal pulmonary Outcome = prevention of fatal pulmonary

embolismembolism

What do you think of this RCT?What do you think of this RCT?

Questions of HarmQuestions of Harm

• For questions of harm, appropriate study For questions of harm, appropriate study designs include case-control studies and designs include case-control studies and cohort studies cohort studies

For Example:For Example:

Population = patients with replanted digitsPopulation = patients with replanted digits

Intervention = continue smoking Intervention = continue smoking

Comparative = non-smokingComparative = non-smoking

Outcome = short-term survival of replanted digitsOutcome = short-term survival of replanted digits

What is the problem here?What is the problem here?

Conducting a RCTConducting a RCTConsiderations:Considerations:• Surgical equipoiseSurgical equipoise• Surgical learning curveSurgical learning curve• Differential careDifferential care• RandomizationRandomization• Concealment Concealment • Expertise-based designExpertise-based design• Blinding Blinding • Intention to treat analysis Intention to treat analysis • Loss to follow-upLoss to follow-up• Treatment effects and implications for sample Treatment effects and implications for sample

size calculations.size calculations.

Surgical EquipoiseSurgical Equipoise

• Equipoise = a state of genuine Equipoise = a state of genuine uncertainty RE: benefits, harms that may uncertainty RE: benefits, harms that may result from each of two or more surgical result from each of two or more surgical procedures. procedures.

• There are no scientific or ethical There are no scientific or ethical concerns about concerns about Surgery ASurgery A being better being better than than Surgery BSurgery B for a particular patient for a particular patient

Surgical Learning CurveSurgical Learning Curve

• Surgeon’s cumulative experienceSurgeon’s cumulative experience

• Continuous refinement of patient Continuous refinement of patient selection, operative technique, and selection, operative technique, and post-operative care post-operative care

• What is the problem here?What is the problem here?

Differential CareDifferential Care

• In OR: better hemostasis, give In OR: better hemostasis, give antibiotics to A and not B, staff person antibiotics to A and not B, staff person does surgery as compared to residentdoes surgery as compared to resident

• Outside the OR: more frequent follow-Outside the OR: more frequent follow-up, physiotherapy to A but not to Bup, physiotherapy to A but not to B


RandomizationRandomization

• Even or odd number birth dateEven or odd number birth date

• Flip a coinFlip a coin

• Alternate chart numbersAlternate chart numbers

• Random number tablesRandom number tables

• Automated telephone systemAutomated telephone system

• Internet randomization system Internet randomization system

What are appropriate randomization What are appropriate randomization techniques?techniques?

RandomizationRandomization

• Randomize as close to surgery as Randomize as close to surgery as possiblepossible

• For exampleFor example: Breast reduction RCT: Breast reduction RCT

ConcealmentConcealment

• Randomization by itself is not Randomization by itself is not adequate. We need to conceal the adequate. We need to conceal the randomization process. randomization process.

• In some trials envelopes are used In some trials envelopes are used carrying the randomization armcarrying the randomization arm


Expertise-based DesignExpertise-based Design

• Patients are randomized to surgeons who Patients are randomized to surgeons who do their operation of preference, as do their operation of preference, as opposed to randomizing patients to a opposed to randomizing patients to a treatment group.treatment group.

• Each participating centre must have some Each participating centre must have some surgeons doing each type of operationsurgeons doing each type of operation

BlindingBlinding

There are 6 potential levels of blinding: There are 6 potential levels of blinding:

1.1.The patientsThe patients2.2.The clinicians who administer the The clinicians who administer the

treatment treatment 3.3.The clinicians care for the patients during The clinicians care for the patients during

the trialthe trial4.4.The individuals who assess the patients The individuals who assess the patients

throughout the trial and collect the datathroughout the trial and collect the data5.5.The data analystThe data analyst6.6.The investigators who interpret and write The investigators who interpret and write

the results of the trialthe results of the trial

BlindingBlinding

• Surgeons ?Surgeons ?

• Patients ?Patients ?

BlindingBlinding

Placebo EffectPlacebo Effect • If a patient knows he/she received a If a patient knows he/she received a

treatment that he/she believes is better, treatment that he/she believes is better, than he/she may feel better even if the than he/she may feel better even if the there is no underlying benefit. there is no underlying benefit.

• The same holds true for the surgeon or The same holds true for the surgeon or designated assessor for the study if they designated assessor for the study if they are not blindedare not blinded

Intention to Treat AnalysisIntention to Treat Analysis

• The analysis of the outcomes is based on The analysis of the outcomes is based on the treatment arm to which patients were the treatment arm to which patients were randomized, and not on which surgical randomized, and not on which surgical treatment they received. treatment they received.

• Includes all patients, regardless of Includes all patients, regardless of whether they actually satisfied the entry whether they actually satisfied the entry criteria, received the treatment to which criteria, received the treatment to which they were randomly allocated, or deviated they were randomly allocated, or deviated from the protocol. from the protocol.

Loss to Follow-UpLoss to Follow-Up

• Failure to account for all patients at end of Failure to account for all patients at end of the study may invalidate the RCT and the study may invalidate the RCT and reduce study power reduce study power

• Researchers suggest that < 5% loss Researchers suggest that < 5% loss probably leads to little bias, whereas > probably leads to little bias, whereas > 20% loss potentially threatens validity 20% loss potentially threatens validity

Treatment Effect and Sample Size Treatment Effect and Sample Size

Treatment Effect:Treatment Effect:

– Effect sizeEffect size: The size of the difference : The size of the difference that the study is designed to detect. that the study is designed to detect. The minimum clinically important The minimum clinically important difference (MCID) is the smallest difference (MCID) is the smallest difference between 2 groups that difference between 2 groups that would be clinically worth detecting. would be clinically worth detecting.

Treatment Effect and Sample SizeTreatment Effect and Sample Size

Sample Size:Sample Size:

– Power varies directly in proportion to Power varies directly in proportion to the number of participants. The the number of participants. The larger the sample size, the greater is larger the sample size, the greater is the power and more information the power and more information about the true difference is obtained. about the true difference is obtained.

Hulley SB, Cummungs SR, Browner WS, Grady D, Hearst N, Newman TB. Designing Clinical Research, 2nd Edition. Lippincott Williams & Wilkins, Philadelphia, 2001

Power Analysis

• To make a statistical inference, we To make a statistical inference, we need to set two hypotheses: need to set two hypotheses: – Null hypothesis (Null hypothesis (therethere is no difference) is no difference)

– Alternate hypothesis (there is a Alternate hypothesis (there is a difference). difference).

Power AnalysisPower Analysis

Type I Error: Type I Error: alpha (alpha () )

Type II Error: Type II Error: beta (beta ())

Understanding Power Analysis Understanding Power Analysis

• Typically Typically is = 0.05 and is = 0.05 and = 0.2 and the = 0.2 and the power = 1 - power = 1 - =.80 =.80

Sample Size CalculationSample Size Calculation

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Conducting a RCT in SurgeryConducting a RCT in Surgery

• In order to conduct high quality, large In order to conduct high quality, large RCTs multi-centre collaboration is RCTs multi-centre collaboration is required. required.

• Collaboration with biostatisticians, Collaboration with biostatisticians, health economists, epidemiologists, health economists, epidemiologists, and clinical trialists and clinical trialists

Beware!Beware!

• Not all published RCTs are reported well Not all published RCTs are reported well or are of good methodological quality.or are of good methodological quality.

• Guidelines exist for:Guidelines exist for:1.1. The Reporting of RCTs (i.e. CONSORT) and The Reporting of RCTs (i.e. CONSORT) and

2.2. The appraisal of RCT methodological The appraisal of RCT methodological quality (i.e. Detsky Quality Assessment quality (i.e. Detsky Quality Assessment Scale)Scale)

Quality of ReportingQuality of Reporting

• Consolidated Standards of Reporting Consolidated Standards of Reporting Trials (CONSORT)Trials (CONSORT)

• Checklist of essential items that should Checklist of essential items that should be included in reports of RCTs and a be included in reports of RCTs and a diagram for documenting the flow of diagram for documenting the flow of participants through a trialparticipants through a trial

CONSORT ChecklistCONSORT Checklist1.1. How participants were allocated to interventions How participants were allocated to interventions2.2. Scientific background and explanation of rationale. Scientific background and explanation of rationale.3a.3a. Eligibility criteria for participants. Eligibility criteria for participants.3b.3b. The settings & locations where the data were collected. The settings & locations where the data were collected.4.4. Precise details of the interventions Precise details of the interventions5.5. Specific objectives and hypotheses Specific objectives and hypotheses6a.6a. Defined primary and secondary outcome measures. Defined primary and secondary outcome measures.6b.6b. Methods used to enhance the quality of measurements Methods used to enhance the quality of measurements 7a.7a. How sample size was determined. How sample size was determined.7b.7b. Explanation of any interim analyses Explanation of any interim analyses 8a.8a. Method used to generate the random allocation sequence. Method used to generate the random allocation sequence.8b.8b. Details of any restriction [of randomization] Details of any restriction [of randomization] 9.9. Method used to implement the random allocation sequence Method used to implement the random allocation sequence 10.10. Who generated the allocation sequence, who enrolled Who generated the allocation sequence, who enrolled

participants, and who assigned participants to their participants, and who assigned participants to their groups.groups.

Assessing Methodological Quality Assessing Methodological Quality

• In a quality assessment scale, the In a quality assessment scale, the responses to the individual items are responses to the individual items are summed to create an overall summary summed to create an overall summary score representing trial qualityscore representing trial quality– i.e. Detsky Quality Scale, Jadad Scalei.e. Detsky Quality Scale, Jadad Scale

Jadad ScaleJadad Scale

Please read the article and try to answer thePlease read the article and try to answer the

following questions (see attachedfollowing questions (see attached

instructions):instructions):

1.1. Was the study described as randomized Was the study described as randomized (this includes the use of words such as (this includes the use of words such as randomly, random, and randomization)?randomly, random, and randomization)?

2.2. Was the study described as double Was the study described as double blind?blind?

3.3. Was there a description of withdrawals Was there a description of withdrawals and dropouts?and dropouts?

Jadad Scale Jadad Scale cont.cont.Scoring the items:Scoring the items:

• Either give a score of 1 point for each “yes” or 0 points for each Either give a score of 1 point for each “yes” or 0 points for each “no.” There are no in-between marks.“no.” There are no in-between marks.

• Give 1 additional point if: For question 1, the method to generate Give 1 additional point if: For question 1, the method to generate the sequence of randomization was described and it was the sequence of randomization was described and it was appropriate (table of random numbers, computer generated, appropriate (table of random numbers, computer generated, etc.)etc.)

And/or: If for question 2 the method of double blinding was And/or: If for question 2 the method of double blinding was described and it was appropriate (identical placebo, active described and it was appropriate (identical placebo, active placebo, dummy, etc.)placebo, dummy, etc.)

• Deduct 1 point if: For question 1, the method to generate the Deduct 1 point if: For question 1, the method to generate the sequence of randomization was described and it was sequence of randomization was described and it was inappropriate (patients were allocated alternately, or according inappropriate (patients were allocated alternately, or according to date of birth, hospital number, etc.)to date of birth, hospital number, etc.)

And/or For question 2, the study was described as double blind but And/or For question 2, the study was described as double blind but the method of blinding was inappropriate (e.g., comparison of the method of blinding was inappropriate (e.g., comparison of tablet versus injection with no double dummy)tablet versus injection with no double dummy)

Jadad Scale Jadad Scale cont.cont.

Thoma et al (Plast. Reconstr. Surg. 114: 1137, 2004.)

Systematic ReviewsSystematic Reviews


• ““The application of scientific strategies The application of scientific strategies that limit bias to the systematic that limit bias to the systematic assembly, critical appraisal, and assembly, critical appraisal, and synthesis of all relevant studies on a synthesis of all relevant studies on a specific topic” specific topic”

Systematic ReviewsSystematic Reviews

Aim to:Aim to:

• Summarize the existing literature Summarize the existing literature

• Resolve conflicts or controversies in Resolve conflicts or controversies in the literature the literature

• Clarify the results of multiple studiesClarify the results of multiple studies

• Evaluate the need for further studiesEvaluate the need for further studies

Conducting Systematic ReviewsConducting Systematic Reviews

1.1. Before embarking on a RCT, you must Before embarking on a RCT, you must be familiar with the “cutting edge” of be familiar with the “cutting edge” of knowledge for a health care problemknowledge for a health care problem

1.1. It is important to summarize this It is important to summarize this “cutting edge evidence” in the form of “cutting edge evidence” in the form of a systematic review and apply it to a systematic review and apply it to your clinical practiceyour clinical practice

Narrative Vs. Systematic ReviewsNarrative Vs. Systematic Reviews

Cook DJ, Mulrow CD, Haynes RB. Ann Intern Med 1997;126(5):376-380

Narrative ReviewNarrative Review Systematic ReviewSystematic Review

Research question is Research question is often broadoften broad

Well-focused clinical questionWell-focused clinical question

Search strategy is not Search strategy is not defined or systematicdefined or systematic

Explicit search strategy, outlining Explicit search strategy, outlining study inclusion/exclusion criteriastudy inclusion/exclusion criteria

Article selection is not Article selection is not systematic systematic

Article selection is specific to Article selection is specific to inclusion/exclusion criteriainclusion/exclusion criteria

Appraisal of study Appraisal of study quality may not be quality may not be performedperformed

Articles are critically appraised Articles are critically appraised and strengths and weaknesses and strengths and weaknesses documenteddocumented

Qualitative summary of Qualitative summary of findingsfindings

Qualitative or quantitative Qualitative or quantitative analysis of findingsanalysis of findings

Meta-AnalysisMeta-Analysis

• The results of the primary studies that The results of the primary studies that meet the standards for inclusion in a meet the standards for inclusion in a review are mathematically pooled to give review are mathematically pooled to give a result that is more precise because of a result that is more precise because of the overall increase in numbers of study the overall increase in numbers of study participants contributing data. participants contributing data.

Meta-analysisMeta-analysis

Aim to:Aim to:• Resolve controversy over whether a true Resolve controversy over whether a true

effect exists, when results have been effect exists, when results have been variable in single studiesvariable in single studies

• Validate a statistically non-significant Validate a statistically non-significant

but clinically important result in a small but clinically important result in a small studystudy

Meta-AnalysisMeta-Analysis

• Frequently, it is not feasible to conduct a Frequently, it is not feasible to conduct a meta-analysis in surgery meta-analysis in surgery

• If the data accumulated from the primary If the data accumulated from the primary studies are of poor quality or too studies are of poor quality or too heterogeneous to be reasonably pooled, a heterogeneous to be reasonably pooled, a quantitative meta-analysis needs to be quantitative meta-analysis needs to be abandoned in favor of a systematic abandoned in favor of a systematic review review

Heterogeneity resulting from differences in clinical features of a Heterogeneity resulting from differences in clinical features of a population that is being studied or treated.population that is being studied or treated.

Systematic Reviews / Meta-analysisSystematic Reviews / Meta-analysis

• Systematic reviews and meta-analyses of Systematic reviews and meta-analyses of the effectiveness of treatments can be the effectiveness of treatments can be performed based on RCTs and / or performed based on RCTs and / or observational studies observational studies

• However, RCTs are the traditional study However, RCTs are the traditional study design of choice for primary studies used design of choice for primary studies used in meta-analyses, as they are the most in meta-analyses, as they are the most likely to be valid likely to be valid

Steps for Conducting a Systematic ReviewSteps for Conducting a Systematic Review

1.1. Form a clinically relevant research questionForm a clinically relevant research question2.2. Develop a detailed research protocolDevelop a detailed research protocol3.3. Perform an exhaustive systematic search Perform an exhaustive systematic search

of the available literatureof the available literature4.4. Critically appraise the quality of selected Critically appraise the quality of selected

articlesarticles5.5. Extract relevant data Extract relevant data 6.6. Perform a statistical or qualitative analysis Perform a statistical or qualitative analysis

of the extracted resultsof the extracted results7.7. Interpret the findings, and address the Interpret the findings, and address the

strengths and weaknesses of selected strengths and weaknesses of selected articles and of the review itselfarticles and of the review itself

Quality AssessmentQuality Assessment

• Methodological Quality Assessment Methodological Quality Assessment Scales:Scales:– Hoving index (Hoving et al. Spine 26:196, Hoving index (Hoving et al. Spine 26:196,

2001)2001)– Oxman and Guaytt index (Oxman and Oxman and Guaytt index (Oxman and

Guyatt. J. Clin. Epidemiol. 44:1271, 1991)Guyatt. J. Clin. Epidemiol. 44:1271, 1991)

• Quality of Reporting Checklist:Quality of Reporting Checklist:– QUORUMQUORUM

QUORUM QUORUM StatementStatement

QUORUM QUORUM Flow Flow

DiagramDiagram

THANK YOU!THANK [email protected]@mcmaster.ca

randomized controlled trials, systematic reviews and meta-analysis achilleas thoma, md, msc, frcs(c)...

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