On assessing the presence of evaluation-time bias in progression-free survival in randomized trials
Article first published online: 21 JUN 2010
Copyright © 2010 John Wiley & Sons, Ltd.
Volume 10, Issue 3, pages 213–217, May/June 2011
How to Cite
Kay, R., Wu, J. and Wittes, J. (2011), On assessing the presence of evaluation-time bias in progression-free survival in randomized trials. Pharmaceut. Statist., 10: 213–217. doi: 10.1002/pst.443
- Issue published online: 16 MAY 2011
- Article first published online: 21 JUN 2010
- progression-free survival;
- logrank test
Evaluation (or assessment)–time bias can arise in oncology trials that study progression-free survival (PFS) when randomized groups have different patterns of timing of assessments. Modelling or computer simulation is sometimes used to explore the extent of such bias; valid results require building such simulations under realistic assumptions concerning the timing of assessments. This paper considers a trial that used a logrank test where computer simulations were based on unrealistic assumptions that severely overestimated the extent of potential bias. The paper shows that seemingly small differences in assumptions can lead to dramatic differences in the apparent operating characteristics of logrank tests. Copyright © 2010 John Wiley & Sons, Ltd.