Dear everyone,
I would appreciate any views you have on the following question relating to 'Intention To Treat' and 'Per Protocol' analysis.
The paper "Intention to Treat: a review" by Gupta (2011) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3159210/ states that "According to Fisher et al. (1990), the ITT analysis includes *all* randomized patients in the groups to which they were randomly assigned, regardless of their adherence with the entry criteria, regardless of the treatment they actually received, and regardless of subsequent withdrawal from treatment or deviation from the protocol." Gupta goes on to say that: "A (better) application of the ITT approach is possible if complete outcome data are available for all randomized subjects. Care must always be taken to minimize missing responses and to continue to follow up those who withdraw from treatment."
So, in my way of thinking, if we randomly assigned patients into two groups (say 'placebo' [group A] and 'treatment' [group B]) at the start of an experiment then, regardless of noncompliance, protocol deviations or withdrawal from treatment, statistical analysis would be carried out to test, say,significant differences between groups A and B as they originally were allocated. In this ITT scenario the outcome for 'drop outs' would have to be imputed.
Am I correct in my assumptions above?
Per protocol analysis, in comparison, means that only patients who complete the trial *according to the protocol* are used in the analysis.
In a hypothetical study, say patients were allocated at the start into one of two groups, X and Y, some patients died, were lost to follow up, dropped out or withdrew in both groups. Patients who completed the trial adhered to their initially allocated groups. Analysis was conducted on the patients which remained in groups X and Y. Therefore, am I correct in thinking that this is a per protocol analysis?
I would be very grateful for your views on this.
Kind Regards,
Kim
Dr Kim Pearce PhD, CStat, Assoc. Fellow HEA
Senior Statistician
Haematological Sciences
Room MG261
Institute of Cellular Medicine
William Leech Building
Medical School
Newcastle University
Framlington Place
Newcastle upon Tyne
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Tel: (0044) (0)191 208 8142
-----Original Message-----
From: Karen Marshall (PGR)
Sent: 27 July 2016 16:35
To: Kim Pearce <[log in to unmask]>
Subject: Quick question
Hi Kim could you spare 5 mins to help me identify if I did ITT analysis on the data or not. There has been a query from a peer reviewer suggesting it was a per-protocol analysis. In the protocol we said we would do an ITT. I think we used all the data we had for every patient but some did drop out or died during the study. My number is 07753884774 or I can ring you when it is convenient.
Cheers karen
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