For validity the more serious problem is the number of lost to follow-up,
that here appears to be low = 7% (9/129).
Incomplete adherence to protocol isn't a problem for validity (in fact, it's
a factor that enhances confidence with statistically significant results)
but just IF analysis is performed according to INTENTION TO TREAT, that is
that the outcome data for patients that dind't adhere to protocol are
analysed in the original randomization group.
If it's not clear, I can tell you in Italian ...
Ciao
dott. Federico Barbani
Servizio Committenza
Azienda USL di Modena
via San Giovanni del Cantone 23
41100 MODENA
tel 059/435813 - 435731
-----Messaggio originale-----
Da: Evidence based health (EBH)
[mailto:[log in to unmask]] Per conto di Giovanni Simeone
Inviato: giovedì 18 marzo 2010 0.23
A: [log in to unmask]
Oggetto: methodological dilemma
I'm a general pediatrician with interest in EBM since few months. I'm
studying an article on
NEJM 2009 "Preemptive Use of High-Dose Fluticasone for Virus-Induced
Wheezing in Young
Children" by Francine Ducharme et altr. In this study ( see slide attached)
48/129 patient
were non adherent to study protocol equivalent at 37%. We have patient who"
discontinued
study drugs" 35/129 and patient who "discontinued study "( lost at
follow-up ) 9/129. I
know the "rule of the thumb" to consider the limit of 20% for lost at
follow up, but if the
adherence to protocol (people who discontinued study drugs) were so high the
study is still
valid? Anyway even if the final result is clinically and statistically
significant...can i transfer
in to my clinical practice these results, if , like in this study 37% of
randomized are't
adherent ?
Thank you in advance for ...your patience and for your answer
Giovanni Simeone
General Pediatrician
National Health Service
Brindisi- Italy
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