All participating research groups have appropriate ethics approval for the use of their data in the proposed secondary analyses. A listing of the participating studies, the names of the study representatives collaborating on this project, and the organizations providing ethical review for the studies can be found in Additional file 3: Table S3. The Human Research Protection Office of Washington University in St. Louis has stated that this collaborative meta-analysis paradigm does not require ethical approval beyond what has been provided to the individual participating groups.
