[1] St Franciscus Gasthuis, Dept Rheumatol, NL-3004 BA Rotterdam, Netherlands
[2] St Franciscus Gasthuis, Dept Internal Med, NL-3004 BA Rotterdam, Netherlands
[3] St Franciscus Gasthuis, Dept Clin Chem, NL-3004 BA Rotterdam, Netherlands
[4] Erasmus MC, Dept Rheumatol, Rotterdam, Netherlands
[5] Erasmus Univ, Inst Hlth Policy & Management, Rotterdam, Netherlands
[6] St Franciscus Gasthuis, Dept Stat & Educ, NL-3004 BA Rotterdam, Netherlands