CRP and rheumatoid arthritis: The independent cohorts of recently diagnosed DMARD-naïve seropositive (n = 35) and seronegative (n = 12) RA patients included in the validation study did not differ in age, sex, symptom duration until RA diagnosis, CRP, ESR, TJC, SJC, DAS28 and presence of erosions (Supplementary Table S1).