Validation of a prediction rule for disease outcome in patients with recent-onset undifferentiated arthritis: moving toward individualized treatment decision-making [corrected] [published erratum appears in ARTHRITIS RHEUM 2008 Oct;58(10):3278]. - van Der Helm-van Mil AH; Detert J; le Cessie S; Filer A; Bastian H; Burmester GR; Huizinga TWJ; Raza K (Arthritis & Rheumatism, 2008)