What are "sub-studies" within a clinical trial primarily used for?

Sub-studies within a clinical trial serve a critical purpose in enhancing the depth of the research findings. They are specifically designed to explore particular hypotheses or secondary endpoints that are not the main focus of the primary trial. While the primary trial investigates a key question or primary endpoint, sub-studies allow researchers to dive deeper into related questions, collect additional data, or examine different aspects of the intervention or population under study.

These can include investigations into the mechanisms of action of a treatment, special population studies, or even exploratory analyses that may inform future research directions. By facilitating a more nuanced understanding of the main study's results, sub-studies can contribute valuable insights that can enhance the overall impact of the clinical trial without detracting from the primary objectives.

The other options relate to areas outside of the defined scope and utility of sub-studies. Summarizing the entire trial process, conducting administrative tasks, and training new researchers do not reflect the specific intent behind sub-studies that aim to deepen and expand knowledge in targeted areas of interest within the broader research framework.