Dear List members
Now we are conducting a cross-over RCT to assess two products marketed in
Saudi Arabia. Patients are randomly assigned to three groups(old, new and a
placebo). All groups are receiving education. Basline laboratory
investigation were taken and each patient undergo a running period to
monitpr the contol dose. Then they will be followed into two phase each
phase last for 16 weeks with two weeks as a washout period in-between.
Laboratory investigation include FBS, 2hPP, HBA1C (monitored every four
weeks) in addition to daily home gluco-monitoring.
So far 7o patients were concluded. Our target is to reach 150. We faced
great difficulty in recruiting patients to finsih the study, following
almost two years. Our preliminary analysis shows that the difference is not
impressive between the three groups using ANOVA. Few indicators were
significant. However there are significant difference with regard to the
amount of dose in favour of single dose irrespective of drugs.
Our questions as follows
Is this sample is enough compared to similar studies?
Could we explain the difference in dose by patients' compliance?
The few significant results of ANOVA could it be explained by the effcet of
Placebo ?
Is there any references for similar fidings and similar studies?
Thanks
Dr. Mohi Eldin Magzoub
E.Mail
[log in to unmask]
Our question is this
Is this sample is enough?
-----Original Message-----
From: Simon, Steve, PhD <[log in to unmask]>
To: <[log in to unmask]>
Date: 07/صفر/1421 06:27 ص
Subject: When is a placebo needed?
>I was looking at a couple of papers for journal club. The first looks at a
>new treatment that requires once-daily dosing rather than multiple-daily
>dosing. The belief is that superior compliance with once-daily dosing will
>lead to as good as or better outcomes. Surprisingly, though, the paper
>looked at a placebo as the comparison group rather than a multiple-daily
>dosing alternative.
>
>The second looks at as-needed dosing compared with regular dosing, and
again
>used a placebo as the control. It seems like a regular dosing of an active
>drug is the more appropriate comparison.
>
>But if the researchers need to start first by showing that the medication
is
>superior to placebo, I guess that is okay. But both papers then seem to
>criticize other research that does what I consider the more relevant
>comparison.
>
>"On the other hand, once-daily BUD 200ug was found to be as effective as
>twice-daily BUD 100 ug in adults with mild-to-moderate asthma, although
this
>study was not placebo controlled. In another study, which also lacked a
>placebo group, once-daily BUD 800ug was less effective than twice-daily BUD
>400ug for long-term management of PEF, asthma symptoms, and rescue
>medication use." (Nuyak et al 2000)
>
>"Juniper et al compared regular and as-needed usage and found regular usage
>to be superior. In a more recent study in which a quality of life
>questionnaire was used, the difference between as-needed and regular use
>were statistically significant, but the authors did not find that the
degree
>of improvement with regular use was clinically significant compared with
>as-needed use. In neither of those studies was a placebo comparison
>included; thus we are not certain whether the as-needed use of intranasal
>corticosteroids is better than placebo treatment." (Jen et al 2000)
>
>I'm not sure why these studies need to be placebo controlled. Clearly they
>can be blinded through the use of a placebo, but that defeats the purpose
of
>showing equivalent or better results because the regimen is easier to
comply
>with. I suspect that what the authors were really criticizing though is
that
>the research did not have a third arm: 1=once-daily, 2=twice-daily
(positive
>control), 3=placebo (negative control). Or alternately: 1=as-needed dosing,
>2=regular dosing (positive control), 3=placebo (negative control).
>
>So does it make sense to look at a placebo at all when the interest is in
>whether once-daily dosing is as good as or better than multiple-daily
dosing
>or whether as-needed dosing is as good as or better than regular dosing?
>There's both a pragmatic aspect and an ethical aspect to this question. I'm
>more interested in the pragmatic aspect, but you are welcome to address
>either or both aspects.
>
>The two papers are:
>
>Nuyak AS et al. Once-daily mometasone furoate dry powder inhaler in the
>treatment of patients with persistent asthma. Ann Allergy Asthma Immunol
>2000;84:417-424.
>
>Jen A et al. As-needed use of fluticasone propionate nasal spray reduces
>symptoms of seasonal allergic rhinitis. J Allergy Clin Immunol
>2000;105(4)732-738.
>
>Steve Simon, [log in to unmask], Standard Disclaimer.
>STATS - Steve's Attempt to Teach Statistics: http://www.cmh.edu/stats
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