Many thanks to all who replied to my query. I think that I
have enough leads to follow. I apologise for omitting the
dsubject line from the previous email. It went off before
I was quite ready!
The original query was:
Dear Allstaters,
I have colleagues who are carrying out a meta-analysis of
post-operative pain. They are interested in the
proportions of subjects experiencing `moderate' and
`severe' pain. This is because Department of Health
targets are in these terms.
Many studies report pain as a visual analogue scale, rather
than in the clinical categories which are needed. They give
either mean and SD or median and IQR. We can define
moderate pain as 30 to 66 mm on a 100 mm line, and severe
pain as 67+ mm.
Does anyone know of any work which would enable us to
estimate these percentages from VAS data given in this way?
VAS does not follow a normal distribution and it's shape
depends on the mean. I think the work would have to be
concerned specifically with the properties of VAS pain
scales.
Alternatively, can anyone let me have some large data sets
of VAS pain scores?
Martin
The replies received were:
------------------------------------------------------------------
Dear Martin,
Conversion of a continuous outcome to an OR for
meta-analysis was the subject of Whitehead A, Bailey A,
Elbourne D. Combining summaries of binary outcomes with
those of continuous outcomes in a meta-analysis. Journal
of Biopharmaceutical Statistics 1999; 9(1):1-16. I have a
paper in press with Statistics in Medicine which goes the
other way around, i.e,. from OR to effect size, which I can
send you a copy of if you think it would help. Not quite
the question you asked, I know, but relevant.
Sue
Miss Sue Chinn Reader in Medical Statistics
Department of Public Health Sciences King's College, London
5th Floor Capital House 42 Weston Street
London SE1 3QD
tel no. 020 7848 6607
fax no. 020 7848 6605
------------------------------------------------------------------
Dear Martin,
It would be better if your colleagues carried out the
analysis on the more sensitive scale if possible and then
translated the result as late as possible.
A transformation I have found useful for VAS is the logit
My motto is "additive at the point of study, relevant at
the point of application"
(See my reply to your comment on equivalence in my RSS read
paper.)
There is quite a lot of work on analysing VAS scales. A
paper I found useful in writing the cross-over trial book
is:
Aitken RC.
Measurement of feelings using visual
analogue scales.
Proc R Soc Med. 1969
Oct;62(10):989-93. Review. PMID:
4899510; UI: 70012230
Regards
Stephen
Professor Stephen Senn
Department of Statistical Science &
Department of Epidemiology and Public Health
University College London
Room 126, 1-19 Torrington Place
LONDON WC1E 6BT
Tel: +44 (0) 20 7679 1698
Fax: +44 (0) 20 7383 4703
Email: [log in to unmask]
webpage: http://www.ucl.ac.uk/~ucaksjs/
-------------------------------------------------
------------------------------------------------------------------
Dear Martin,
We usually used BS-11 (1 box=10 mm of VAS). I do not think
that I can give you any specific answer to your question
but the following references might help:
1. M. P. Jensen, P. Karoly and S. Braver (1986). The
Measurement of Clinical Pain Intensity: a Comparison of Six
Methods. Pain, 27, 117-126 2. M.P Jensen, J.A. Turner and
J. M. Romano (1994). What is the maximum number of levels
needed in pain intensity measurement. Pain 58, 387-392.
Best regards,
Lada Mitchell
Statistics & Data Management, Medical Research
International R & D (UK)
Napp Pharmaceuticals Limited
Tel.: +44 (0)1223 424444 Ext. 2847
Fax.: +44 (0)1223 426002
Email: [log in to unmask]
------------------------------------------------------------------
Dear Martin
I think you will find this information you want in the
following book:
McQuay H, Moore RA
An evidence based resource for pain relief
Oxford University Press, 1998
It is a year or so since I read it, but I think they wished
to perform meta analyses and therefore wanted to be able to
convert between the different types of methods used for
rating pain. They had lots of data which enable them to
choose appropriate cut-offs.
Best wishes
Caroline
________________________________________________________________________
Caroline J. Dore
Head, Statistical Consultancy Service, Department of
Epidemiology and Public Health
Imperial College School of Medicine, Hammersmith Campus, Du
Cane Road, London W12 0NN
Email: [log in to unmask]
Phone 020 8383 8427 Fax 020 8383 8573
------------------------------------------------------------------
Try Professor Henry McQuay
[log in to unmask]
Dr Anita Holdcroft MB ChB, MD, FRCA
Reader in Anaesthesia,
Hammersmith Hospital,
Imperial College School of Medicine,
Du Cane Road, London W12 0HS
020 8383 3290
Fax 020 8749 9974
Email: [log in to unmask]
------------------------------------------------------------------
If no-one else can help, I do have access to data from
a number of studies using VAS, mainly (if not all)
dermatology, amounting to somewhere over 500 measurements
in all; the largest group being up to 8 measurements each
on 14 subjects. Other data sets have more subjects, but
only 1 or 2 measurements.
I would want to contact the various investigators
for permission before passing any data on.
Paul T Seed
([log in to unmask]) Mail to:
Maternal & Fetal Research Unit North Wing, St Thomas'
Hospital, Lambeth Palace Road, London SE1 7EH
Employer:
Maternal & Fetal Research Unit Department of Obstetrics &
Gynaecology, Guy's Kings and St. Thomas' School of
Medicine, King's College, London
tel (+44) (0) 20 7960 5889
fax (+44) (0) 20 7620 1227 web page (useful Stats
handouts): http://www-phm.umds.ac.uk/Statinfo/other.htm
------------------------------------------------------------------
Hi Martin
My midwifery students use the scale but with additional
information, I will see if I can get hold of a copy.
Ruth Helm Lecturer in Informatics and Statistics.
The Centre for Health Practice. R&D. The University of
Wolverhampton. Walsall Campus
Gorway Road. Walsall WS1 3BD
Tel 01902 322843
------------------------------------------------------------------
I phoned (well emailed actually) a friend .this is what he
said.
Paul Marchant
Centre for Research and Graduate Studies
Leeds Metropolitan University
Calverley St., Leeds.
LS1 3HE
Tel 0113 2833074
Fax 0113 2836764
> -----Original Message-----
> From: Johnson, Mark [HES]
> Sent: 10 October 2000 09:42
> To: Marchant, Paul [RDO]
> Subject: RE: Pain scales
>
> Paul,
> Your colleague could try the early chapters of a book by
McQuay and Moore - An evidence-based resource for pain
relief >
> They may however already be aware of this source >
> Best wishes, > Mark.
> >
Thanks again,
Martin
------------------------------------------------
Martin Bland
Prof of Medical Statistics
Dept of Public Health Sciences
St. George's Hospital Medical School
London SW17 0RE
England
Tel: (+44) (0)20 8725 5492
Fax: (+44) (0)20 8725 3584
Email: [log in to unmask]
Web pages: www.sghms.ac.uk/depts/phs/staff/jmb/jmb.htm
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