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Updated: Jul 2, 2026

The Adjuvant Efficacy of Angong Niuhuang Pill in the Treatment of Viral Encephalitis: A Meta-Analysis of Randomized Controlled Trials
Published on: April 19, 2024
The analysis of randomised controlled trial data with more than one follow-up measurement. A comparison between
Jos W R Twisk1, Wieke de Vente
1Department of Methodology and Applied Biostatistics, Institute of Health Sciences, Vrije Universiteit, Amsterdam, The Netherlands. jwr.twisk@vumc.nl
Abstract:
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.
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