Dear AndrewJ
Hello.
Regarding the "What is a systematic review?", as the others mentioned
, a systematic review is an overview of primary evidence that used
explicit and reproducible methods; in other words, a review with a
methodology:
- clearly defined: aims, study design, dependent and the
other variables (predictors, confounders, modifiers, exposure,
intervention...), participants and study population, cases, referents
and outcomes. Definition of each aforementioned section related to
the study design
- define quality/ inclusion criteria for studies
- define search strategy
- summarise study methods including methodology for data extraction
and analysis.
Meta-analysis is a statistical analysis that combines data from
several studies addressing the same question in the same way to
produce a single estimate which can be done by using two methods.
They are :
1- individual patient data analysis by combining raw data from
diferent studies
2- summary data analysis in which one should do the next steps.
a) Check homogeneity of effect.
b) Estimates from studies are combined to give a
single estimate of the effect.
As you know,the estimate is usually a weight average of studies
and weights usually relate to the variance of the estimate in
each study.
For dichotomous data one can use either
- Mantel-Haenszel Odds Ratio or
- Peto Odds Ratio.
For continuous data one can use either
- weighted mean difference or
- weighted standardised mean difference.
As my mind, one of the best reference for the Meta-Analysis is the
Kenneth J. Rothman's book ,"Modern Epidemiology", 1998.
Cheer
Ghasem Yadegarfar
Date: Thu, 26 Aug 1999 09:23:32 +1200
Subject: RE: Term "systematic review"
From: Andrew Jull <[log in to unmask]>
To: "[log in to unmask]" <[log in to unmask]>,
Andrew Jull <[log in to unmask]>
Cc: [log in to unmask]
Reply-to: Andrew Jull <[log in to unmask]>
Dear all
several people have kindly replied to me outlining the general understanding
in medicine/health about what a systematic review is - Bart's reponse is an
example. And this was certainly my oringinal understanding. However, GV
Glass who developed the technique and put together the first meta-analysis
of the effectiveness of psychotherapy reported in 1976, coined the term not
just for the stats part, but for the whole process, starting with a
question, a search strategy, retrieval of all studies, quality assessing
them and synthesising the data. At some point in the transfer to medicine,
meta-analysis has come to stand just for the statistical component of
systematic review / overview and I am interested in understanding how and
why. Can anyone help me with this. At least one other person has an interest
in this topic, so rather than just replying to me, perhaps put the responses
out to the list for general interest?
regards
Andrew Jull
Clinical Nurse Consultant
Auckland Hospital
Private Bag 92024
Auckland
NEW ZEALAND
Phone: +64 9 3797440
Fax:+64 9 3072818 (external)
7718 (internal)
> -----Original Message-----
> From: Dr. Bart M. Demaerschalk [SMTP:[log in to unmask]]
> Sent: Thursday, 26 August 1999 10:23
> To: Andrew Jull
> Cc: [log in to unmask]
> Subject: Re: Term "systematic review"
>
> Andrew Jull wrote:
> >
> > Dear all
> >
> > I am interested in the term systematic review/overview and where it
> > orginated from or who coined it. Until recently I had taken
> meta-analysis to
> > be the statistical component of a systematic review, but reading Glass
> who
> > coined the term meta-analysis, this would seem quite incorrect. The
> process
> > Glass outlined for conducting a meta-analysis (i.e. clear question,
> search
> > strategy, outcomes of interest, quality assessment of studies) is
> similar to
> > that of systematic review. I had thought Mulrow might have used it in
> her
> > 1987 article, but rereading that the terms systematic and review are
> used
> > but not in juxtaposition. Can anybody enlighten me?
> >
> > Andrew Jull
> > Clinical Nurse Consultant
> > Auckland Hospital
> > Private Bag 92024
> > Auckland
> > NEW ZEALAND
> > Phone: +64 9 3797440
> > Fax:+64 9 3072818 (external)
> > 7718 (internal)
> In response to Andrew Jull's question regarding the various terms
> describing systematic reviews: A qualitative systematic review
> summarizes but does not statistically combine the results of primary
> studies. A quantitative systematic review (or meta analysis) uses
> statistical methods to combine the results of primary studies. See
> Mulrow CD, Cook DJ, and Davidoff R (1998) Systematic Reviews: Critical
> Links in the Great Chain of Evidence. In Mulrow and Cook (Eds)
> Systematic Reviews: Synthesis of Best Evidence for Health Care Decisions
> (pp. 1-4). Philadelphia, American College of Physicians.
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