Observational clinical research that aims to evaluate a biomarker or diagnostic method with regards to its ability to predict the propability of remission or worsening of a condition. Patients are observed either spontaneously over time or during therapy. Biomarkers/diagnostic methods may be able to predict which therapy is most promising (Description adapted from: https://www.aerzteblatt.de/archiv/64080/Studientypen-in-der-medizinischen-Forschung)