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Systematic Reviews EPI 214. Course Goals Learn the skills necessary to design and complete a systematic review (but know when to seek statistical help) Be able to critique published systematic reviews Have a fun and interesting class. Course Overview. Grading and Homework.

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systematic reviews epi 214
Systematic ReviewsEPI 214
  • Course Goals
    • Learn the skills necessary to design and complete a systematic review (but know when to seek statistical help)
    • Be able to critique published systematic reviews
    • Have a fun and interesting class
grading and homework
Grading and Homework
  • Grading is not a priority, but a requirement
    • 60% homework
    • 40% final exam
  • Homework
    • BRING 2 HARD COPIES TO CLASS! (one to hand in, one to use for notes, if desired).
    • If you are going to miss class, let us know ahead of time and e-mail homework to our class TA (Ashok: krishsysreview2011@gmail.com)
  • Final Exam:
    • Will be distributed in class on April 28th
    • Please complete and hand in by May 12th, 5pm, to Olivia Deleon in China Basin Suite 5706-02 (5th floor)  mailbox 0560 OR e-mail to our class TA)
sections
Sections
  • Steve Bent Rm 6702
  • Wendy Katzman Rm 6704
  • Dejana Braithwaite Rm 5759
ticr professional conduct statement clarifications for this class
TICR Professional Conduct StatementClarifications for this class
  • I will maintain the highest standards of academic honesty
  • I will neither give nor receive aid in examinations or assignments unless such cooperation is expressly permitted by the instructor
  • I will conduct research in an unbiased manner, report results truthfully, and credit ideas developed and work done by others
  • I will not use answer keys from prior years
  • I will write answers in my own words, and, when collaboration is permitted, acknowledge collaborators when answers are jointly formulated
epi 214 lecture 1 designing a systematic review meta analysis

EPI-214: Lecture 1 Designing a Systematic Review (Meta-analysis)

Dejana Braithwaite

Assistant Professor

UCSF Department of Epidemiology and Biostatistics

slide7

8 steps of a systematic review Bent et al. 2004

1 Formulate research question

Lecture 1

2 Develop review protocol

3 Initiate search strategy

4 Apply inclusion /exclusion criteria

5 Quality appraisal

6 Data abstraction

7 Analysis

Lectures 1, 2 & 3

8 Interpret findings

what s a systematic review
What’s a Systematic Review?

“A review of the evidence on a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant primary research, and to extract and analyze data from the studies that are included in the review.”

Cochrane Collaboration

and meta analysis
…and meta-analysis?

Statistical combination of ≥ 2 studies to produce single estimate of effect of exposure

rapid growth
Rapid growth

Pubmed search

up to 3/29/2010:

Systematic review >1.5 million hits

Meta-analysis >40,000 hits

  • up to 1/1/1990:
  • Systematic review 300,994 hits
  • Meta-analysis 845
the cochrane collaboration international systematic review initiative
The Cochrane CollaborationInternational systematic review initiative
  • Archie Cochrane’s vision led to the opening of the first Cochrane centre (in Oxford, UK) in 1992 and the founding of the Cochrane Collaboration in 1993

Source: http://www.cochrane.org/cochrane/archieco.htm

slide12

Meta-analysis in the NYT accessed 3/30/10

Sattar N, et al. Statins and risk of incident diabetes: a collaborative meta-analysis of randomised statin trials. Lancet. 2010 Feb 27;375(9716):735-42. Epub 2010 Feb 16.

narrative review
Narrative review

Key characteristics

Uses informal, unsystematic and subjective methods

Searching quality and synthesis not described

  • Disadvantages
    • may have preconceived biases and may overestimate value of some studies
systematic review
Systematic review

Driven by evidence-based medicine movement

Advantages:

  • Reduces bias
  • Replicable
  • Resolves controversy between conflicting findings
  • Provides reliable basis for decision making
use of meta analysis as a prelude to clinical trials
Use of meta-analysis as a prelude to clinical trials

Define pre-trial expected effect sizes

sample size estimation

  • Determine effect estimates in key subgroups (e.g. based on gender, race/ethnicity or age)
  • Identify sources of heterogeneity in prior studies
  • Addressing these sources in design phase of new trial
use of meta analysis in study designs that are not clinical trials
Use of meta-analysis in study designs that are not clinical trials

Observational studies

  • Studies evaluating diagnostic tests
  • “IPD” = individual patient data studies
  • Qualitative studies (meta-ethnography)
slide19

Meta-analyses

IPD*

Systematic reviews

*IPD= individual participant data

resources required for systematic reviewing
Resources required for systematic reviewing

Can be time consuming

Team science (to reduce bias)

Bibliographic software (e.g. Endnote)

Statistical software (if appropriate)

slide21

Step 1

Formulate research question

finer criteria for research question
FINER criteria for research question

Feasible

Interesting

Novel

Ethical

Relevant

Hulley S, et al. 2001 Designing Clinical Research

slide23

Anatomy of a research question – PICO(T)

Patient

Intervention (or “Exposure”)

Comparison

Outcome

(Type of study)

slide24
Patient:

Disease or condition

Stage, severity

Demographic characteristics (age, gender, etc.)

Intervention (or “Exposure”):

Type of intervention or exposure

Dose, duration, timing, route, etc.

Comparison:

Absence of risk or treatment

Placebo or alternative therapy

slide25

Outcome:

    • Risk or protective
    • Dichotomous or continuous
    • Type: mortality, morbidity, quality of life, etc.
  • Type of study:
    • RCTs
    • Cohort
    • Case-control
    • Cross-sectional
    • All
formulation of an etiology question
Formulation of an etiology question

Exposure

Outcome

Is smoking a risk factor for lung cancer?

Patient

Exposure

Are people who smoke regularly at a greater risk of developing lung cancer as compared to those who do not smoke?

+ cohort & case-control studies

Outcome

Comparison

formulation of a diagnosis question
Formulation of a diagnosis question

Test (intervention)

Outcome

Is MRI a good test for breast cancer?

Test (intervention)

Outcome

Is MRI a more sensitive and specific test in diagnosing breast cancer as compared to mammography?

Comparison

slide28

Step 2

Develop review protocol

protocol
Protocol

Background

Objectives

Pre-determined selection criteria

Planned search strategy

Planned data abstraction

Proposed method of synthesis of findings

Establishment of an advisory group

slide30

Step 3

Initiate search strategy

where to locate studies
Where to locate studies

Pubmed

CINAHL

Web of Science

EMBASE

PsychINFO

additional sources to identify studies for systematic reviews

Additional sources to identify studies for systematic reviews

Reference lists of retrieved articles

Manual searching of relevant publications

Experts in the field

Corresponding or first authors of published

studies identified for the systematic review

issues to consider

Issues to consider

Publication bias

Search bias

pubmed citation example
Pubmed citation example

Title: Interaction between 5-HTTLPR genotype, stressful life events and depression

Search terms:

Life stress

Life event

Depression

Depress

Serotonin transporter

5-HTTLPR

Interaction

Moderation

Risch et al. JAMA 2010

slide35

Step 4

Apply inclusion /exclusion criteria

inclusion exclusion criteria
Inclusion/exclusion criteria

P - Population

I - Intervention

C - Comparison (if necessary)

O - Outcome

T - Type of study (if necessary)

Subject headings OR Textwords

To find studies using all of the PICO elements:

P and I and C and O (and T)

exclusion criteria
Exclusion criteria

Keep log of excluded studies

Note reasons for exclusion

Have eligibility checked by more than one reviewer

Develop strategy to resolve disagreements

search strategy example
Search strategy example

Risch et al. JAMA 2010

slide40

Step 5

Quality appraisal

principles of quality appraisal
Principles of quality appraisal

Quantitative studies

Internal Validity

allocation bias, confounding, attrition, statistical

analysis, intervention integrity, withdrawals and

dropouts

External Validity (generalizability or applicability)

quorum for trials
QUORUM for trials

Moher et al. Improving the quality of reports of meta-analyses of randomized controlled trials: The QUORUM statement. Lancet 1999;354:1896-1900

moose for observational designs
MOOSE for observational designs

Stroup et al. Meta-analysis of observational studies in epidemiology. JAMA 2000;283:2008-12

qualitative research
Qualitative research

Checklists available to assess the quality of qualitative research. E.g. CASP appraisal tool for qualitative research (http://www.phru.nhs.uk/casp/qualitat.htm)

slide46

Recruit participants

SELECTION BIAS

ALLOCATION BIAS

Allocate to intervention and control groups

Intervention group

Control group

CONFOUNDING

INTEGRITY OF INTERVENTION

Implement intervention

Implement intervention

INTENTION-TO-TREAT

Follow-up participants

Follow-up participants

WITHDRAWALS/ DROP OUTS

Measure outcomes

BLINDING OUTCOME ASSESSORS

Measure outcomes

DATA COLLECTION METHODS

Analyze outcomes

Analyze outcomes

STATISTICAL ANALYSIS

slide47

Step 6

Data abstraction

data abstraction elements

publication details

study design

population details (n, characteristics)

intervention details

setting

outcomes and findings

Data abstraction elements

data abstraction examples

Data abstraction examples

http://www.cochrane.org

slide52

Step 7

Analysis

synthesizing the evidence
Synthesizing the Evidence

NARRATIVE SYNTHESIS

primary studies explained qualitatively and summarized

META-ANALYSIS

findings summarized and then combined statistically

is there heterogeneity
Is there heterogeneity?

No

Yes

Meta-analysis

Narrative synthesis

Deal with heterogeneity?

(e.g. subgroup analysis)

slide58

Step 8

Interpret findings

interpretation of results
Interpretation of results

Strength of the evidence

  • Trade-offs between benefits and harms
  • Implications for practice, policy
strength of the evidence
Strength of the evidence
  • Describe the overall strength of the evidence
  • The quality of the evidence
  • The sizeand consistency of the results
  • Describe biases and limitations of the
  • review process (e.g. difficulties in locating
  • articles, inability to translate non-English
  • articles)
slide61

8 steps of a systematic review Bent et al. 2004

1 Formulate research question

Lecture 1

2 Develop review protocol

3 Initiate search strategy

4 Apply inclusion /exclusion criteria

5 Quality appraisal

6 Data abstraction

7 Analysis

Lectures 1,2 & 3

8 Interpret findings

section 1 assignment developing a protocol for a systematic review
Section 1 AssignmentDeveloping a Protocol for a Systematic Review

Homework:

Write a 1-2 page protocol to address the clinical problem described in the assignment.