Footnotes

• Contributors All authors reviewed and approved the final manuscript. RH: designed the investigation, acquired the data, performed statistical analyses, interpreted the data and wrote the first version of the manuscript. JA: designed the investigation, acquired the data, developed the structure of the arguments and critically reviewed the manuscript. SF: interpreted the data, developed the structure of the manuscript and reviewed the manuscript. RS collected the data and critically reviewed the manuscript. SD: interpreted and collected the data and reviewed the manuscript. OA: collected the data, developed the structure of the manuscript and critically reviewd it. PR: collected the data and reviewed the manuscript. CL: collected the data, interpreted the statistics and reviewed the manuscript. AC: developed the structure of the manuscript, interpreted the data and reviewed the manuscript critically. MS: collected the data, developed the design and the structure of the manuscript and critically reviewed it. RG: developed the design, interpreted the data and critically reviewed the statistics and the manuscript.

• Competing interests RH received research and travel grants from Biogen-Idec and travel grants from Novartis. SF received a travel grant from Biogen-Idec. OA received consulting honoraria from Biogen-Idec. CL has received consulting and speaker's honoraria from Biogen-Idec, Bayer Schering, Novartis, Sanofi, Genzyme and TEVA, and has received research scientific grant support from Bayer Schering, TEVA and MerckSerono. AC has received personal compensation as a speaker or consultant for Bayer Schering, Biogen-Idec, Merck Serono, Novartis, Sanofi-Aventis, and Teva Neuroscience and research support from the German Ministry for Education and Research (BMBF, “German Competence Network Multiple Sclerosis” [KKNMS], CONTROL MS, 01GI0914), Bayer Schering, Biogen Idec, Merck Serono, and Novartis. MS received speakers and consulting honoraria from Bayer Healthcare, Biogen-Idec, Baxter, CSL Behring, Grifols, Merck-Serono, Novartis, Sanofi-Aventis, and Teva. MS is also supported by the Niedersachsen Research Network on Neuroinfectiology (N-RENNT) of the Ministry of Science and Culture of Lower Saxony. His institution received research support from Bayer Healthcare, Biogen Idec, Merck-Serono, Novartis, and Teva. RG received speakers and consulting honoraria, scientific grant support from Baxter, Bayer Healthcare, Biogen-Idec, Merck-Serono, Novartis Pharma, Sanofi-Genzyme and Teva Pharma.

• Ethics approval The research was approved by the local ethic committees of University Bochum and Hannover (no. 4566-13 (Bochum) & 2100-2013 (Hannover)).

• Provenance and peer review Not commissioned; externally peer reviewed.