[1] Univ Hosp Aachen, Dept Nephrol & Rheumatol, RWTH, Aachen, Germany
[2] Friedrich Schiller Univ, Univ Hosp Jena, Dept Internal Med 3, Jena, Germany
[3] Municipal Hosp Ludwigshafen, Dept Internal Med A, Nephrol & Rheumatol, Ludwigshafen, Germany
[4] Cantonal Hosp St Gallen, Dept Rheumatol, St Gallen, Switzerland