Recommendations for intention to treat analysis (Hollis and Campbell, 1999)
ITT is better regarded as a complete trial strategy for design, conduct and analysis rather than as an approach to analysis alone.
Design
- Decide whether the aim is pragmatic or explanatory. For pragmatic trials, intention to treat is essential
- Justify in advance any inclusion criteria which when violated would merit exclusion from intention to treat analysis
Conduct
- Minimise missing response on the primary outcome
- Follow up subjects who withdraw from treatment
Analysis
- Include all randomised subjects in the groups to which they were allocated
- Investigate the potential effect of missing response
Reporting
- Specify that intention to treat analysis has been carried out, explicitly describing the handling of deviations from randomised allocation and missing response
- Report deviations from randomised allocation and missing response
- Discuss the potential effect of missing response
- Base conclusions on the results of intention to treat analysis