 As a precondition for participating in this study, the subjects were provided information in writing and verbally about the details of the study. Informed consent was obtained from all volunteers. Before the beginning of the study, all participants were subject to a medical examination in the Clinic for Rheumatology Internal Medicine III, Friedrich Schiller University, Jena. The RA was diagnosed according to the 1987 revised criteria of the American Rheumatism Association ARA. Severity of disease activity was evaluated by using the disease activity score DAS 28. 