Dear Julia,
The best method depends on the question you want to answer.
Pragmatic treatment, in which case all 160 should be analysed, or only
treating biologically confirmed cases the 111. I find that many papers
claim to use ITT but in fact use a whole host of reasons for excluding
people from analysis, some legitimate some less so. Part of the problem is
that researchers are told ITT is good and so claim to use ITT analysis.
But in this case if they wanted a trial in biologically confirmed cases
then they should have randomised people after biological confirmation of
pathogen.
James Woodcock
Julia Valderrama wrote:
> 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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