Evaluation of the results of a randomized controlled trial: How to define changes between baseline and follow-up

Evaluation of the results of a randomized controlled trial: How to define changes between baseline and follow-up

Twisk, J.
Proper, K.

2004

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.

Workplace
Changes
Continuous outcome variables
Dichotomous outcome variables
Multinomial logistic regression
Regression to the mean
Covariance
Data analysis
Dietary intake
Follow up
Intermethod comparison
Multivariate logistic regression analysis
Outcomes research
Physical activity
Statistical analysis
Analysis of Variance
Counseling
Diet
Exercise
Humans
Occupational Health
Randomized Controlled Trials
Research Design
Treatment Outcome

http://resolver.tudelft.nl/uuid:5120339e-6356-4c6f-97a7-0bb8d3abd623

https://doi.org/10.1016/j.jclinepi.2003.07.009

150873

Journal of Clinical Epidemiology, 57 (3), 223-228

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