About the Authors

Fiona Maas

f.maas@umcg.nl

Affiliation Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands

Anneke Spoorenberg

Affiliations Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands, Department of Rheumatology, Medical Center Leeuwarden, Leeuwarden, The Netherlands

Elisabeth Brouwer

Affiliation Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands

Reinhard Bos

Affiliation Department of Rheumatology, Medical Center Leeuwarden, Leeuwarden, The Netherlands

Monique Efde

Affiliation Department of Rheumatology, Medical Center Leeuwarden, Leeuwarden, The Netherlands

Rizwana N. Chaudhry

Affiliation Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands

Nic J. G. M. Veeger

Affiliation Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands

Peter M. A. van Ooijen

Affiliation Department of Radiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands

Rinze Wolf

Affiliation Department of Radiology, Medical Center Leeuwarden, Leeuwarden, The Netherlands

Hendrika Bootsma

Affiliation Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands

Eveline van der Veer

Affiliation Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands

Suzanne Arends

Affiliations Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands, Department of Rheumatology, Medical Center Leeuwarden, Leeuwarden, The Netherlands

Competing Interests

Anneke Spoorenberg has received research grants from Abbott, Pfizer, and Wyeth and consulting fees from Abbvie, Pfizer, and UCB. Elisabeth Brouwer and Suzanne Arends have received research grants from Abbott, Pfizer, and Wyeth. Reinhard Bos has received research grants and consulting fees from Pfizer. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials. The other authors have declared that they have no competing interests.

Author Contributions

Conceived and designed the experiments: AS EB HB EV SA. Performed the experiments: FM AS EB RB ME RC PO RW. Analyzed the data: FM. Contributed reagents/materials/analysis tools: FM AS NV EV SA. Wrote the paper: FM AS SA. Critically revised the manuscript: AS EB RB ME RC NV PO RW HB EV SA.