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Inconsistent reporting of surrogate outcomes in randomised clinical trials: cohort study
Jeppe Lerche la Cour1, Jesper Brok, Peter C Gøtzsche
1Copenhagen Trial Unit, Rigshospitalet, Copenhagen University Hospital, DK-2100 Copenhagen, Denmark. Jeppelerche@hotmail.com
Objective:
To assess if authors of randomised clinical trials convey the fact that they have used surrogate outcomes and discussed their validity.
Design:
Cohort study.
Setting:
Six major general medical journals.
Participants:
Randomised clinical trials published in 2005 and 2006 that used a surrogate as a primary outcome.
Results:
Of 626 published randomised clinical trials, 109 (17%) used a surrogate as a primary outcome. Of these trials, 62 (57%, 95% confidence interval 47% to 67%) clearly reported that the primary outcome was a surrogate. Only 38 (35%, 26% to 45%) also discussed the validity of the surrogate.
Conclusion:
Only about one third of authors of randomised clinical trials that used a surrogate as a primary outcome reported adequately on the surrogate. Better reporting is needed.
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