You can follow a patient across studies by linking their participant key using the steps listed below (for more about participant keys, please refer to this article).
1. Log in to the Ocean portal.
2. Choose the Studies tab.
3. Locate the first study form and select "Configure".
4. Ensure that the first study is set to "Generate a participant key for this study" and select "Save".
5. Select "Configure" for the subsequent study.
6. This time, select "Align this study's participant keys with" and select the first study from the dropdown menu.
7. Save your changes.
8. Repeat steps 5 and 6 for each study that you wish to link.