The analysis of randomised controlled trial data with more than one follow-up measurement. A comparison between different approaches.

J.W.R. Twisk, W. de Vente

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When more than one follow-up measurement is analysed in a randomized controlled trial, there is no consensus how to analyse the overall intervention effect in a proper way. Mostly, longitudinal analysis of covariance is used, because with this method a correction is made for possible regression to the mean. However, in this paper it is shown that this method (mostly) leads to an overestimation of the intervention effect. A possible solution is the use of autoregression, although this does not seem to be the best solution, because it leads to an overcorrection. Due to these flaws, in this paper a new approach is introduced in which a correction for the baseline value is made for the first follow-up, but no correction is made for the remaining follow-up measurements. © 2008 The Author(s).
Original languageEnglish
Pages (from-to)655-660
Number of pages6
JournalEuropean Journal of Epidemiology
Issue number10
Publication statusPublished - 2008


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