Article type
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Abstract
Background: It has been reported that trials using the modified intention-to-treat (mITT) analysis are increasingly being published in the medical literature. In 2010, CONSORT recommended abandoning any mention of intention-to-treat analysis in favour of a clear description of who was included in each analysis. Recently a meta-epidemiological study showed that trials deviating from intention-to-treat overestimated the treatment effect compared to trials using standard intention-to-treat (Abraha, BMJ, 2015). Consequently, we were interested whether mITT is still being used in randomised trials.
Objectives: To determine the incidence of mITT trials published between 2007 and 2014.
Methods: PubMed, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), ISI Web of Knowledge, Ovid, HighWire Press, Science-Direct, Ingenta, Medscape, BioMed Central, Springer, and Wiley, were searched to identify randomized trials that used the modified intention-to-treat as the primary analysis. The search strategy used the following terms: 'modified intention-to-treat', 'modified intent-to-treat' and 'modified ITT'.
Results: Using the reported search strategy, a total of 1951 records were retrieved; 250 records were randomly selected from these and the respective full-texts were obtained for evaluation. Trials that used only a modified intention-to-treat for a primary analysis amounted to 222 (88.8%). The remaining trials also used an intention-to-treat analysis (n = 24) or a per protocol analysis (n = 4). Overall, the number of mITT trials increased 3.4 times from 2007 to 2014. The incidence of mITT trials among all the published randomised trials increased from 0.5% in 2007 to 2.5% in 2014 (P value for trend = 0.010).
Conclusions: Trials that report a mITT are increasingly being published in the medical literature. The incidence is underestimated since the search was limited to trials that used the word 'modified' in the intention-to-treat description. The use of mITT should be abandoned in favour of a clear description of who was included in final analysis.
Objectives: To determine the incidence of mITT trials published between 2007 and 2014.
Methods: PubMed, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), ISI Web of Knowledge, Ovid, HighWire Press, Science-Direct, Ingenta, Medscape, BioMed Central, Springer, and Wiley, were searched to identify randomized trials that used the modified intention-to-treat as the primary analysis. The search strategy used the following terms: 'modified intention-to-treat', 'modified intent-to-treat' and 'modified ITT'.
Results: Using the reported search strategy, a total of 1951 records were retrieved; 250 records were randomly selected from these and the respective full-texts were obtained for evaluation. Trials that used only a modified intention-to-treat for a primary analysis amounted to 222 (88.8%). The remaining trials also used an intention-to-treat analysis (n = 24) or a per protocol analysis (n = 4). Overall, the number of mITT trials increased 3.4 times from 2007 to 2014. The incidence of mITT trials among all the published randomised trials increased from 0.5% in 2007 to 2.5% in 2014 (P value for trend = 0.010).
Conclusions: Trials that report a mITT are increasingly being published in the medical literature. The incidence is underestimated since the search was limited to trials that used the word 'modified' in the intention-to-treat description. The use of mITT should be abandoned in favour of a clear description of who was included in final analysis.