Intention to treat analysis

Intention to treat analysis

In epidemiology, an intention to treat (ITT) analysis (sometimes also called Intent to Treat) is an analysis based on the initial treatment intent, not on the treatment eventually administered. ITT analysis is intended to avoid various misleading artifacts that can arise in intervention research. For example, if people who have a more refractory or serious problem tend to drop out at a higher rate, even a completely ineffective treatment may appear to be providing benefits if one merely compares those who finish the treatment with those who were never enrolled in it. For the purposes of ITT analysis, everyone who begins the treatment is considered to be part of the trial, whether they finish it or not.

Rationale

Intention to treat analyses are done to avoid the effects of crossover and drop-out, which may break the randomization to the treatment groups in a study. Intention to treat analysis provides information about the potential effects of treatment policy rather than on the potential effects of specific treatment.

In contrast, "efficacy subset analysis" selects the subset of the patients who received the treatment of interest--regardless of initial randomization--and who have not dropped out for any reason. This approach can :
* introduce biases to the statistical analysis
* inflate the type I error; this effect is greater the larger the trialcite journal
doi=10.1016/S0197-2456(00)00046-5
author=Lachin JM
journal=Controlled Clinical Trials
title=Statistical Considerations in the Intent-to-Treat Principle
year = 2000
month = June
volume = 21
issue = 3
pages = 167-189
pmid = 10822117] .

Full application of intention to treat can only be performed where there is complete outcome data for all randomized subjects.

Although intention to treat is widely cited in published trials, it is often incorrectly described and its application may be flawed.

References

ee also

*Randomized controlled trial
*Clinical trial
*Per-protocol analysis

External links

* [http://www.jr2.ox.ac.uk/bandolier/booth/glossary/ITT.html Intention to Treat] - Bandolier's definition
* [http://www.tufts.edu/~gdallal/itt.htm Intention to Treat] - Tufts.edu
* [http://people.bu.edu/mlava/ITT%20Workshop.pdf Intention-to-Treat Analysis] - Bu.edu
* [http://bmj.bmjjournals.com/cgi/content/full/319/7211/670 What is meant by intention to treat analysis? Survey of published randomised controlled trials] - BMJ
* [http://www.cmaj.ca/cgi/content/full/165/10/1339 Intention-to-treat principle] - CMAJ
* [http://www.mja.com.au/public/issues/179_08_201003/her10586_fm.html Inclusion of patients in clinical trial analysis: the intention-to-treat principle] - [http://www.mja.com.au/ eMJA]


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