Hi
I have been approacted by a specialist registrar wishing to conduct a study in which a
treatment is to be given to patients to reduce the incidence of diarrhoea. He plans to
use two wards in one hospital. All new patients attending one ward will be allocated
to
the test treatment and all new patients in the other ward will form a control group.
The
outcome of interest is incidence of diarrhoea during one month of follow up. He then
plans to allow for a "washout" period, of up to one month, after which the two wards
crossover to the other treatment. His question was; how many patients do I need? (He
didn't think about how he might analyse his results!)
My first reaction was that this is a cluster randomised trial with one cluster per arm
(ignoring the "crossover" for the moment) and in the absence of any background
information regarding likely incidence in the control group, I was not in a position
to
offer much advice.
I do not feel that a crude linear contrast of incidence rates involving the two
hospital
wards over the two treatment periods is really appropriate. What do othes feel? Can
anyone suggest a sensible way forward?
regards
Bernie
-----------------------------------------
Bernie Higgins, email: [EMAIL PROTECTED]
Department of Mathematics, University of Portsmouth
Room 18, Floor 1, Buckingham Building
Lion Terrrace, Portsmouth PO1 3HE
Tel 023 92 846361 Monday & Tueday
023 92 286236 Wednesday - Friday
.
.
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