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Table 1 Baseline clinical and MRI characteristics of patients included in the discovery and validation cohorts

From: A search to the target tissue in which RA-specific inflammation starts: a detailed MRI study to improve identification of RA-specific features in the phase of clinically suspect arthralgia

 Discovery cohort (n = 225)Validation cohort (n = 209)p value
Age in years, mean (SD)44 (13)43 (12)0.26
Female, n (%)174 (77)165 (79)0.77
Symptom duration in weeks, med (IQR)17 (9–32)20 (9–44)0.28
Localisation of initial symptoms  0.39
 Small joints, n (%)189 (84)165 (79) 
 Small and large joints, n (%)22 (10)26 (13) 
 Large joints, n (%)13 (6)17 (8) 
Localisation of initial symptoms  0.76
 Upper extremities, n (%)162 (72)134 (70) 
 Upper and lower extremities, n (%)39 (17)34 (18) 
 Lower extremities, n (%)23 (10)24 (13) 
Symmetrical localisation of initial symptoms, n (%)166 (74)127 (70)0.35
Morning stiffness ≥ 60 min, n (%)72 (36)62 (34)0.83
68-TJC, med (IQR)6 (3–10)5 (2–10)0.23
Fulfilling the EULAR definition of CSA, n (%)153 (68)131 (63)0.29
CRP level in mg/L, med (IQR)3 (3–5)3 (3–4)0.59
ESR level in mg/L, med (IQR)6 (2–13)6 (2–14)0.12
RF, n (%)46 (20)41 (20)0.92
ACPA, n (%)28 (12)30 (14)0.66
MRI-detected presence of subclinical inflammation (MRI positivity), n (%)114 (51)74 (35)0.002
  1. p value: chi-square tests, Fishers’s exact tests, Student’s t tests, and Wilcoxon’s rank sum tests were applied as appropriately. SD standard deviation, n number of patients, RA rheumatoid arthritis, med median, IQR interquartile range, EULAR European League Against Rheumatism, CSA clinically suspect arthralgia, BME bone marrow edema, min minutes, TJC tender joint count, CRP C-reactive protein, ESR erythrocyte sedimentation rate, RF rheumatoid factor, ACPA anti-citrullinated protein antibody, MRI magnetic resonance imaging