Ulf,
As far as I am aware, the usual reason for conducting an open-label trial is
when blinding is considered to be either not practical or not ethical.
However, in such cases bias is reduced by ensuring that the raw data is
analysed by people who are not aware of the identity of the comparative
treatments.
You mentioned trials evaluating insulin treatment in diabetes care but do
not provide information on what insulin treatment is being compared with. In
people with Type 1 diabetes it would not be ethical to withhold insulin
treatment and in Type 2 diabetes, if insulin treatment is being compared
with oral antidiabetic drugs than it would not be practical to blind. If two
different types of insulin are being compared, then participants can usually
guess which insulin they are allocated because of having to calculate the
appropriate insulin dose for food intake thus introducing the possibility of
bias and so on.
Does this answer your question?
With best wishes
Anjana Patel
Anjana Patel BPharm, MSc, PhD, MRPharmS
Independent Pharmaceutical Scientist and Writer
UK
----- Original Message -----
From: "Ulf Eriksson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, March 02, 2007 5:13 PM
Subject: Open-labelled diabetes trial
Dear friends
Can I please have your assistance on this matter?
Many studies in diabetes care, particularly on insulin-treatment, are
carried out in an open-label fashion.
Can one consider the endpoints in a study of diabetes to be so objective
and sufficiently un-biased that this is appropriate to do?
In critical appraisal we learn (and teach) that the measurement of
endpoints should be either blinded or objective (or both).
What is your opinion on this?
Regards
Ulf Eriksson
Karlskrona
Sweden
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