Data items

Task: Describe how the information and variables to be collected were chosen. List and define all study level and participant level data that were sought, including baseline and follow-up information. If applicable, describe methods of standardising or translating variables within the IPD datasets to ensure common scales or measurements across studies.

Text: The variables to be requested as part of the IPD are chosen in consultation between the EBCTCG Secretariat and the Steering Committee. The lists of variables for each cycle of the overview are made available on the EBCTCG website and include a mixture of baseline and follow-up information. The variable list is provided to the responsible trialists along with the data request, and includes the coding used by the EBCTCG Secretariat to store the IPD to be analysed. Some trialists submit the data in this format, using the EBCTCG codes, but most submit it using their own coding or data structure and this is then processed, with appropriate rules for each variable, to create a standardised dataset for each trial.