The DOI matches its Crossref record; 8 of the 8 references it cites were found in a registry or an index.
Improper analysis of trials randomised using stratified blocks or minimisation
Abstract
Many clinical trials restrict randomisation using stratified blocks or minimisation to balance prognostic factors across treatment groups. It is widely acknowledged in the statistical literature that the subsequent analysis should reflect the design of the study, and any stratification or minimisation variables should be adjusted for in the analysis. However, a review of recent general medical literature showed only 14 of 41 eligible studies reported adjusting their primary analysis for stratification or minimisation variables. We show that balancing treatment groups using stratification leads to correlation between the treatment groups. If this correlation is ignored and an unadjusted analysis is performed, standard errors for the treatment effect will be biased upwards, resulting in 95% confidence intervals that are too wide, type I error rates that are too low and a reduction in power. Conversely, an adjusted analysis will give valid inference. We explore the extent of this issue using simulation for continuous, binary and time‐to‐event outcomes where treatment is allocated using stratified block randomisation or minimisation. Copyright © 2011 John Wiley & Sons, Ltd.
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Cites
Pocock, S. J., Assmann, S. E., Enos, L. E., & Kasten, L. E. (2002) · Statistics in Medicine · doi:10.1002/sim.1296 · Cited by 1,077
Generation of allocation sequences in randomised trials: chance, not choice
Schulz, K. F., & Grimes, D. A. (2002) · The Lancet · doi:10.1016/s0140-6736(02)07683-3 · Cited by 774
The method of minimization for allocation to clinical trials
Scott, N. W., McPherson, G. C., Ramsay, C. R., & Campbell, M. K. (2002) · Controlled Clinical Trials · doi:10.1016/s0197-2456(02)00242-8 · Cited by 651 · cited 2×
“A majority of the statistical literature suggests any baseline variable involved in randomisation should also be included in the analysis[9, 12, 13, 14, 15, 16, 17, 18] though some argue this is not always sensible[19].”
BackgroundStratified Randomization for Clinical Trials
Kernan, W. N., Viscoli, C. M., Makuch, R. W., Brass, L. M., & Horwitz, R. I. (1999) · Journal of Clinical Epidemiology · doi:10.1016/s0895-4356(98)00138-3 · Cited by 627
Treatment allocation by minimisation
Altman, D. G., & Bland, J. M. (2005) · BMJ · doi:10.1136/bmj.330.7495.843 · Cited by 550
Properties of permuted-block randomization in clinical trials
Matts, J. P., & Lachin, J. M. (1988) · Controlled Clinical Trials · doi:10.1016/0197-2456(88)90047-5 · Cited by 321
Properties of the urn randomization in clinical trials
Wei, L. J., & Lachin, J. M. (1988) · Controlled Clinical Trials · doi:10.1016/0197-2456(88)90048-7 · Cited by 308
Randomization in clinical trials: Conclusions and recommendations
Lachin, J. M., Matts, J. P., & Wei, L. J. (1988) · Controlled Clinical Trials · doi:10.1016/0197-2456(88)90049-9 · Cited by 272
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Metadata
- Authors
- Kahan, B. C., & Morris, T. P.
- Venue
- Statistics in Medicine
- Publisher
- Wiley
- Published
- 2011-12-04
- Volume
- 31
- Issue
- 4
- Pages
- 328-340
- ISSN
- 0277-6715 (ISSN-L)
- 1097-0258
- OpenAlex
- W2131593307
- Cited by
- 332
- References
- 8
- FWCI
- 9.18
- Type
- journal article
- Language
- en
- Open access
- closed
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