Print Email Facebook Twitter Evaluation of the results of a randomized controlled trial: How to define changes between baseline and follow-up Title Evaluation of the results of a randomized controlled trial: How to define changes between baseline and follow-up Author Twisk, J. Proper, K. Publication year 2004 Abstract The most common way to evaluate the effect of an intervention is to compare the intervention and non-intervention groups regarding the change in the outcome variable between baseline and follow-up; however, there are many different ways to define "changes". The purpose of this article is to demonstrate how different definitions of "change" used in the analysis can influence the results of a study. Two different randomised controlled trials were used as examples. The results of the analysis showed that for continuous outcome variables, analysis of covariance seems to be the most appropriate because it corrects for the phenomenon of regression to the mean. For dichotomous outcome variables, multinomial logistic regression analysis with all possible changes over time as outcome seems to be the most appropriate, especially because of its straightforward interpretation. A different definition of "change" can lead to different results in the evaluation of the effect of an intervention. Subject WorkplaceChangesContinuous outcome variablesDichotomous outcome variablesMultinomial logistic regressionRegression to the meanCovarianceData analysisDietary intakeFollow upIntermethod comparisonMultivariate logistic regression analysisOutcomes researchPhysical activityStatistical analysisAnalysis of VarianceCounselingDietExerciseHumansOccupational HealthRandomized Controlled TrialsResearch DesignTreatment Outcome To reference this document use: http://resolver.tudelft.nl/uuid:5120339e-6356-4c6f-97a7-0bb8d3abd623 DOI https://doi.org/10.1016/j.jclinepi.2003.07.009 TNO identifier 150873 Source Journal of Clinical Epidemiology, 57 (3), 223-228 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.