Hi Pijush,
For observational studies, it is best (gives the benefit of doubt to the
study) to use the appraisal tool for studies of Harm. In the case of
observational studies, you are biased against the study if you use the
appraisal tool for therapy, which rewards RCTs. On the other hand, if
the observational study is one of a therapy, there will be lots of
biases introduced in the study that could escape detection using that
appraisal tool.
What I would do then is to use the studies of harm tool for the primary
appraisal. But, I would then also consider whether the reason that the
study was done in that manner (instead of as an RCT) was because it
would be either impossible or unethical to do an RCT or if the reason
that an observational study was done had to do with convenience, cost,
or other (maybe nefarious reasons like potential for bias and results
that would put the therapy in the best possible light - as if sponsored
by a proprietary concern) problems and how reasonable those are to
override the greater validity of doing an RCT. Since there are often
confounding factors operating in the results of an observational study,
it is best to critially appraise them with a "jaundiced eye".
I hope that this helps.
Best wishes,
Dan
****************************************************************************
Dan Mayer, MD
Professor of Emergency Medicine
Albany Medical College
47 New Scotland Ave.
Albany, NY, 12208
Ph; 518-262-6180
FAX; 518-262-5029
E-mail; [log in to unmask]
****************************************************************************
>>> Olive Goddard <[log in to unmask]> 10/15/07 8:27 AM >>>
Dear Colleagues,
If anyone has the answer to this query I should be grateful if you would
reply to Pijush directly.
All good wishes,
Olive
Olive Goddard
Centre and Editorial Manager
Centre for Evidence-Based Medicine
Department of Primary Health Care
Old Road Campus, Headington
Oxford, OX3 7LF
.....................................................................
Tel: +44 (0)1865 289337 email: [log in to unmask]
Fax: +44 (0)1865 289336 web: www.cebm.net
Mobile: 07804 625002 web: www.cebmh.com ( http://www.cebmh.com )
>>> "Ray Pijush (RKB) Consultant Physician" <[log in to unmask]>
15/10/2007 13:23 >>>
Dear Dr Goddard,
I would please like to know what critical appraisal tool would one use
for
an observational study like "Thrombolysis with alteplase for acute
ischaemic
stoke in the Safe Implementation of Thrombolysis in Stroke Monitoring
Study
(SITS-MOST)" Wahlgren N et al Lancet Jan 2007; 369; 275-282
Best wishes
Pijush Ray
Dr Pijush Ray MD Med(Cal) FRCP(Lond)
Department of Gerontology
University Hospital
Clifford Bridge Road
Coventry CV2 2DX
PA: Andrea Lovell 02476 965720
Fax No: 02476 966271
DISCLAIMER: This e-mail and any attachments hereto are confidential and
may
contain proprietary information or be legally privileged. This e-mail is
for
the exclusive use of the intended recipient(s) only. If you are not the
intended recipient(s) you must not use, copy, print or rely on this
message
or any attachment or disclose the content to any other person. If you
have
received this e-mail in error please notify the author by replying to
this
e-mail or contact us on [log in to unmask]
-----------------------------------------
CONFIDENTIALITY NOTICE: This email and any attachments may contain
confidential information that is protected by law and is for the
sole use of the individuals or entities to which it is addressed.
If you are not the intended recipient, please notify the sender by
replying to this email and destroying all copies of the
communication and attachments. Further use, disclosure, copying,
distribution of, or reliance upon the contents of this email and
attachments is strictly prohibited. To contact Albany Medical
Center, or for a copy of our privacy practices, please visit us on
the Internet at www.amc.edu.
|