Proposals to enhance the quality of observational cohort studies.

For herbal medicinal products the methodology of observational cohort studies (observational studies, drug monitoring studies, Anwendungsbeobachtung) represents a useful addition to clinical trials. The key objectives are the documentation of efficacy in particular under conditions of everyday medical practice in authentic patients and the documentation of the safety profile. Supplementary to earlier activities, members of the "Clinical Trials of Herbal Medicinal Products" Working Party of the German Society for Phytotherapy have therefore again addressed the issue of observational cohort studies for to enhance the informative value and importance of this clinical research methodology. Recommendations were developed on quality aspects, methodological approaches of observation parameters, and for the reporting of the study's results. Properly planned and conducted observational cohort studies may contribute to the documentation and proof of well-established medicinal use according the EU Directive 2001/83/EC.