Author Contributions: Dr Ramos-Casals had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Ramos-Casals, Tzioufas, Stone.
Acquisition of data: Sisó, Bosch.
Analysis and interpretation of data: Sisó, Bosch.
Drafting of the manuscript: Ramos-Casals, Tzioufas, Sisó, Bosch.
Critical revision of the manuscript for important intellectual content: Tzioufas, Stone, Bosch.
Statistical analysis: Ramos-Casals, Stone, Sisó.
Obtained funding: Ramos-Casals.
Administrative, technical, or material support: Ramos-Casals.
Study supervision: Ramos-Casals, Stone, Sisó, Bosch.
Financial Disclosures: None reported.
Funding/Support: This study was supported by grants from La Marató de TV3 (071810) and Fondo de Investigaciones Sanitarias (080103).
Role of the Sponsor: The funding sources had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript.
Additional Contributions: David Buss, BA, an independent medical writer, provided editorial assistance. His compensation was funded by grants from La Marató de TV3 and Fondo de Investigaciones Sanitarias.