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The impact of modified intention-to-treat reporting randomised trials in meta-analyses

Date and Location




Friday 20 September 2013 - 10:30 - 12:00


Presenting author and contact person

Presenting author


Contact person

Iosief Abraha
Abstract text
Background: A modified intention-to-treat (mITT) analysis with multiple and inconsistent descriptions is increasingly being used in randomized clinical trials (RCTs). However, little is known about the impact of mITT reporting trials included in meta-analyses. In addition, mITT reporting RCTs are likely to be associated with post-randomization exclusions and funding. However, this evidence comes from trials published in few journals. Objectives: 1) To estimate the prevalence of the modified intention-to-treat reporting trials in meta-analyses; 2) to determine differences in terms of post-randomised exclusions among the types of intention-to-treat reporting; 3) to confirm whether mITT is associated with funding. Methods: We searched Pubmed for systematic reviews with at least one intervention RCT from 2006 to 2011. Trials were classified according to the type of intention-to-treat reporting as follows: 1) ITT, trials reporting the use of standard ITT analyses; 2) mITT, trials reporting the use of "modified intention-to-treat" analyses; or 3) "no ITT" trials not reporting the use of any intention-to-treat analyses. Trials reporting the use of ITT with descriptions or conditions different from the standard intention-to-treat definition were classified as mITT. Results: The prevalence of meta-analyses that included trials with mITT reporting ranged from 19% to 39%. Compared to ITT trials, the mITT trials were more likely to report post-randomization exclusions (OR 6.48 [95%CI, 4.11 to 10.21]). Moreover, there was a strong association between trials classified as mITT and for-profit agency sponsorship (OR 7.08 [95%CI, 3.70 to 13.56] ) as well as the presence of authors’ conflicts of interest (OR 3.65 [95%CI, 2.1 to 7.89]). Trials classified as “no ITT” were also associated with funding (OR 1.39 [95%CI, 1.07 to 1.82]; p=0.016). Conclusions: The reporting of mITT is systematically present in meta-analyses. Trials reporting mITT are strongly associated with post-randomization exclusions, for profit funding and presence of conflict of interest.