I believe the several answers to this query underscore my earlier assertion
that there is no single correct way to analyze all situations. An ITT
analysis is the only way to get at the overall benefit-harms tradeoff.
Nevertheless, it is frequently of interest to also examine the subgroup of
patients who actually had the disease or who actually complied. Even if at
present there is no way to sort these out ahead of time, this knowledge will
tell us how much we might gain if we put research efforts into better
diagnosis and prognosis.
David L. Doggett, Ph.D.
Senior Medical Research Analyst
Technology Assessment Group
ECRI, a non-profit health services research organization
5200 Butler Pike
Plymouth Meeting, PA 19462-1298, USA
Phone: +1 (610) 825-6000 ext.5509
Fax: +1(610) 834-1275
E-mail: [log in to unmask]
> -----Original Message-----
> From: Julia Valderrama [SMTP:[log in to unmask]]
> Sent: Tuesday, August 22, 2000 1:26 PM
> To: [log in to unmask]
> Cc: [log in to unmask]
> Subject: ITT question
>
> Hi,
> Thanks a lot for all your comments on intention to treat analysis.
>
> I am looking at a RCT by Dutta D et als, 1996 (Efficacy of norfloxacin
> and doxycycline for the treatment of V cholerae O139 infection)
> where 160 patients were enrolled in the study but just 111 analysed.
> The difference 49 subjects were not included in the analysis because
> they showed culture (-) to Vcholerae O139. There's a table that
> shows comparable characteristics of the patients on admission, but
> for the 111 not for the 160. Is this the way it should be? OR the
> right way would be showing the table with all the subjects entered and
> randomized for the study (i.e 160) and as we have analyzed a 69% of
> that (i.e. 111) because of 49 not being O139 we can conclude that
> realibility of the study is compromised?
>
> Would this be an example of not having followed the intention to treat
> analyis, i.e. once randomised always analysed?
>
> Thanks a lot
> Julia
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