Study concept and design: Jonsson, Theander, Henriksson.
Acquisition of data: Jonsson, Theander, Sjöström, Brokstad, Henriksson.
Analysis and interpretation of data: Jonsson, Theander, Sjöström, Brokstad, Henriksson.
Drafting of the manuscript: Jonsson, Theander, Brokstad, Henriksson.
Critical revision of the manuscript for important intellectual content: Jonsson, Theander, Sjöström, Brokstad, Henriksson.
Statistical analysis: Theander, Sjöström.
Obtained funding: Jonsson, Theander, Henriksson.
Administrative, technical, or material support: Jonsson, Theander, Sjöström, Brokstad, Henriksson.
Study supervision: Jonsson, Theander, Henriksson.
Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Theander reported serving on advisory boards for Roche and Pfizer; receiving payment for lectures from Roche; and receiving reimbursement for travel expenses from Roche and Pfizer. No other disclosures were reported.
Funding/Support: This study was supported by grants from the Malmö University Hospital Foundation, the Malmö University Hospital Cancer Foundation, the Swedish Rheumatism Association, the Strategic Research Program at Helse Bergen, the Regional Health Authority for Western Norway, the Broegelmann Foundation, and the Foundations of Kock, Österlund, and Gustaf V.
Role of the Sponsor: The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Additional Contributions: We are grateful to Peter Olsson, MD (Department of Rheumatology, Lund University, Malmö, Sweden), for assistance with acquisition of data and Bo Cederholm, MD, PhD (Clinical Immunology Laboratory, Skåne University Hospital, Lund, Sweden), for access to laboratory facilities for the analysis of rheumatoid factor. No compensation was received by either of these individuals.