 1.2. Rationale for the planned Studies In the clinical setting the current status of a given disease is often reported as mild, moderate and severe, and the course of the disease over time is described with terms such as stable, progressive, in remission or flare-up. None of these terms has so far been clearly defined for EoE. However, an increasing number of phase 3 therapeutic multi-center trials and natural history studies in patients with EoE will be performed in the near future. In order to set up standardized study protocols and to compare results between different studies a standardized definition of disease activity is a necessity. Taken together, for clinical and for research purposes it is indispensable to define the terms mentioned above by a suitable, reproducible and validated score, which reflects the disease activity as precisely as possible. The necessity for such a score has repeatedly been discussed by the TIGERS and has been underscored by several publications 12. 