Changing platforms without stopping the train: experiences of data management and data management systems when adapting platform protocols by adding and closing comparisons by Hague, D, Townsend, S, Masters, L, Rauchenberger, M, Van Looy, N, Diaz-Montana, C, Gannon, M, James, N, Maughan, T, Parmar, MKB, Brown, L, Sydes, MR, Stampede And Focus4 Investigators