A references are papesr by John Lachin "Statistical Considerations in the Intent to Treat Principle" 21 Controlld Clinical Trials 167 (2000); and Lewis and Machin "Intention to treat -- who should use ITT?" 68 Br. J. Cancer 647 (1993). Pure ITT is irrespective of events occurring post-randomization and classifies subjects wtih respect to the randomized treatment assignment. ICH E9 is also pertinent. Note that ICH E9 refers to the "Full Analysis Set", which appears to me to be something less than pure ITT -- calling for the analysis set to be as close as possible to the "ITT ideal". And in practice, sometimes one will see trials using MITT (modified ITT) which requires the receipt of at least one dose of a study medication.
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