core guide chapter 4 - meta analysis

Question 1

defining the question

Answer 1

begin with clearly defined qn

idea of what info source you will use

Question 2

searching for resources

Answer 2

use bibliographic database
specific search terms eg mesh
combine with Boolean operators - AND, OR, NOT
limit by year/language etc

Question 3

refining the research

Answer 3

use details in qn to guide the search strategy

Question 4

keeping records

Answer 4

accurate bibliographic details, search histories, critique details, key info helps you find things again quickly
reference manager, endnote, mendley useful online

Question 5

selecting research

Answer 5

depends on the purpose of the article
if want quick ans - l;imit to reviews
if want long answer- read all
inclusion and exclusion criteria

Question 6

appraise

Answer 6

read the papers see if
relevant
valid
applicable

Question 7

apply research

Answer 7

only if valid - discuss reasons why not applying it with patient etc

Question 8

reference databases

Answer 8

organise info on all relevant info on the field
medline Embase and psychinfo - all include biomedical info and some other books and publications
advisable to search more than 1 database

Question 9

citation data

Answer 9

citation - reference to another article or source of information
most influential articles are cited the most
information on ISI web of science and google scholher

Question 10

conference abstracts

Answer 10

published first at conferences may appear in official conference proceedings
accessed through Conference proceedings index 0 through Web of Knowledge

Question 11

open access resources

Answer 11

publically funded research is in open access

eg pubmed

Question 12

evidence based medicine resources

Answer 12

see if already been reviewed by a reputable group
Cochrane library - systematic reviews, clinical trials health technology assessments, economic evaluations
BMJ clinical evidence - publish systematic reviews
TRIP database

Question 13

bibliographic software

Answer 13

manage all referenced evidence by enabling you to store it in your own database or library
manual cataloguing of references relating to research or topics
automatic collection and organisation of references from bibliographic databases, library catalogues etc
quick searches for a particular reference
search and retrieval of bibliographical subsets
print/save a list of references
integration with word processing software to insert and format citations and bibliographies
format for data sharing and other packages
format according to a particular style
save full text articles and access them anywhere online

Question 14

list of bibliographic resources

Answer 14

endnote 
Mendeley 
reference manager 
refworks 
Zotero

Question 15

things to consider in a systematic review

Answer 15

address important qn
thorough search
methodological quality assessed and studies weighted
appropriate to combine
publication bias assessed
results interpreted correctly and with a association with the larger picture

Question 16

diagnositic test accuracy studies

Answer 16

aim defined
used gold standard test
appropriate spectrum of participants
disease status established
methods for test described in enough detail
work up bias avoided
observer bias avoided
CI for sensitivity specificity, P/NPV
could results be influenced by the gold standard test
study findings placed in wider context of other diagnostic tests
relevant to clinical practice.

Question 17

qualitive research studies

Answer 17

qn
method appropriate
researchers perspective influence the results
recruitment strategy appropriate for the aims
ethics
transcribed and analysed in a rigorous manner
conclusions justified findings transferablle to other clinical settings
useful insight for clinical practice

Question 18

steps in a systematic review

Answer 18

define qn 
search literature 
appraise studies 
extract data 
synthesise data 
report and apply the findings

Question 19

what should a systematic review be based on

Answer 19

protocol that is produced before:
qn
description of the search strategy - including databases and search items to be used - methods for search eg contacting authors
details of who will perform the search
method for assessing the quality of the search
description of the data to be extracted
method for synthesising the results - qualitive or narrative report of the findings , tables summarising the populations, quantitive synthesis through meta analysis
plan for reporting and applying the results

Question 20

reporting a systematic review

Answer 20

methods of PRIMSA
describe methods
resukts should be in a flow chart
details of included papers in flow charts

Question 21

what is a meta-analysis

Answer 21

statistical analysis of a collection of studies
collected through a systematic review
statistical techniques allow quantitive results to be taken by combining results from all individual studies

Question 22

why conduct a meta-analysis

Answer 22

individual studies have inconsistent findings

insufficient to ans a research qn or provide evidence to base practice

Question 23

advantages of meta analysis

Answer 23

identifies consistant patterns 
include more people 
identify heterogeneity between studies 
explore publication bias 
provide evidence for making decisions

Question 24

extraction …

Answer 24

off main result from each study with probability that this is due to chance

Question 25

checking ….

Answer 25

whether appropriate to pool

Question 26

calculation

Answer 26

of summary result as a weighted average across the studies
weight takes into account the varience of the study reflects the size of the study
greater weight to more informative studies

Question 27

presentation

Answer 27

forrest plots

graphical representation from each study combined with a meta-analysis - combined meta analysis result

Question 28

forest plot

Answer 28

overall estimate is shown at the bottom - diamond
centre respond to summary effect esitimate
width of diamond = confidence interval

Question 29

clinical check if it is appropriate to pool results

Answer 29

judgement of whether reports are reflecting the same thing and therefore that the results are meaningful and helpful
not appropriate if differences in study participants, interventions or outcomes that suggest a different underlying research qn

Question 30

statistical reasons for not pooling

Answer 30

assessed to see if significant variation with respect to populations, exposures, clinical settings, and designs used

Question 31

Galbrith plot

Answer 31

fascilitate the examination of heterogenety
regression line through origen represent the pooled estimate with 95% CI - little heterogeneity 95% studies should fall in the lines
vertical spread describes the extent of herterogenity and the outliers

Question 32

calculating a pooled result

Answer 32

method depends on whether statistical heterogeneity
no heterogeneity - fixed effects model can be used
heterogeneity can be allowed for by doing the random effects model to pool estimates

Question 33

fixed model

Answer 33

no evidence of heterogeneity
study evaluates common treatment/exposure effect
assumes single true/fixed underlying effect

Question 34

random effects model

Answer 34

effects different in different studies
distribution of effects from which the study estimates the means of different effects
sub groups can be pooled in sub analysis

Question 35

what to watch out for in a metanalysis

Answer 35

false impression of consistency across individual study results
systematic variations
appropriate to pool?
possibility all studies have same systematic error
publication bias

Question 36

exploring publication bias

Answer 36

effect may be over or underestimated 
caused when only a subset of information is available 
funnel plots 
link between study size and estimate 
symmetrical = no pub bias