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401 – Painting a Picture of Life in the United States
Modelling and Interpretation of Vaccine Cross-over Clinical Trials Data
Scott Patterson
P�zer
Byron Jones
Novartis Pharma AG
Michael Kenward
University of London
In a cross-over study, subjects are randomized to a sequence of treatments over time with repeated measurements being taken after each treatment. For vaccines, such studies may be done to identify the potential for `boosting' immune response, identifying opportune time of re-vaccination, and/or for the identification of potential alternative dosing regimens (when multiple vaccines of differing mechanism are available) amongst other reasons. Carry-over in such designs is obviously not only assumed but is also desired (unlike most drug cross-over trials where it is regarded as a nuisance). We consider the application of cross-over and carry-over modelling to vaccine cross-over designs in the context of a Balaam's design (data are disguised to actual vaccine and endpoint) based on the approaches of Jones and Kenward (2003, 2ed.). We will show that the cross-over and carry-over methods are readily applicable to vaccine studies and aid/simplify the analysis and interpretation of data arising from such studies.