Dictionary of Evidence-based Medicine.pdf

Dictionary of Evidence-based Medicine 101
Maryland, USA. The thesaurus is used to create the Index Medicus, a directory
of major scientific publications. The MeSH thesaurus has approximately
18 000 main subjects and is regularly updated. Table 4 gives the
main subject classification.
Table 4 MeSH classification
A
B
C
D
E
F
G
H
I
J
K
L
M
N
Z
Anatomy
Organism
Diseases
Drugs and chemical products
Analytical, diagnostic and therapeutic techniques and equipment
Psychiatry and psychology
Biological sciences
Physical sciences
Anthropology, education, sociology and social phenomena
Technology, industry, agriculture and food
Humanities
Information sciences and communication
Named groups
Health
Geographical names
Meta-anaiysis
Meta-analysis refers to the systematic quantitative pooling of available
evidence on a particular research question with the use of appropriate
statistical methods. As such, it forms part of many systematic overviews.
In the context of drug efficacy, clinical trial evidence is sought systematically
and the relevant efficacy outcome data extracted. The data are then
pooled using suitable weights such as sample variance or sample size. The
pooled estimate of efficacy is then presented with the appropriate confidence
bounds to define its precision. Although in medicine, meta-analysis
is most widely used for pooling experimental data from randomized
clinical trials (RCTs), observational data have also been meta-analysed.
Methodology for incorporating observational data in meta-analyses of
RCTs is also available but is not generally adopted.
Most meta-analyses are undertaken on the summary data reported
in the individual trials being pooled and it is usually not possible to check
on any inconsistencies. However, in certain circumstances, the records of
the clinical trialists may be particularly good and the network exists
for obtaining the individual patient data for revalidation (e.g. cancer
clinical trial networks). A meta-analysis undertaken with revalidation and