We use “modified” distributed network model consisting of the following components:
1) Distributed Network: Raw data are located in the individual site throughout the study and only summary tables will be sent to the coordinating center.
2) Common data structure: Data with the common structure will be prepared by the individual study site under the instruction of the coordinating center in charge of the individual study. In the modified distributed network model used in the current early phase of AsPEN, data structure is unique to the individual study and may differ between different studies..
3) Single analytic program: A single analytic program (SAS code) developed by the coordinating center will be circulated to multiple study sites. Each site runs the same programon the data with common structure to yield summary tables which are then sent to the coordinating center where the results from multiple sites are pooled and analyzed.