Table 1

Disease characteristics compared across serology status

VariableSeronegative RA
(n=36)
Seropositive RA
(n=198)
p Value
Age, years55.8 (15.4)50.7 (13.3)0.04
Female, n (%)21 (58.3)124 (62.6)0.63
Disease duration, months4.8 [2.5–11.7]5.9 [2.9–9.9]0.89
Positive for ACPA, n (%)NA187 (94.4)
Positive for RF IgMNA154 (77.8)
Positive for RF IgANA110 (55.6)
DAS*3.9 (1.2)3.4 (1.2)0.03
44 SJC17 [11–25]8 [4–13]<0.001
CRP, mg/L7.3 [3.0–27.0]7.0 [3.0–18.0]0.48
ESR, mm/h14.0 [10.0–29.0]20.5 [12.0–33.0]0.21
Ritchie Articular Index7.5 [3.5–14.0]7.0 [4.0–13.0]0.73
Physician global VAS 0–100 mm49.1 (21.1)38.9 (20.2)0.006
Patient global VAS 0–100 mm50.0 (26.6)49.6 (23.9)0.92
Total US joint score†55 [31–82]25 [15–40]<0.001
US PD joint score16 [7–27]7 [3–14]<0.001
US GS joint score37 [23–58]18.5 [10–27]<0.001
Joints with US synovitis16 [9–20]6 [3–10]<0.001
Total US tendon score3 [0–7]0 [0–3]<0.001
US PD tendon score1 [0–4]0 [0–2]0.008
US GS tendon score2 [0–3]0 [0–2]<0.001
Total van der Heijde-modified Sharp score5.5 [2.0–13.0]4.0 [1.5–8.0]0.20
Joint space narrowing1.5 [0.0–6.0]1.0 [0.0–3.0]0.06
Erosion score3.0 [1.0–6.5]3.0 [1.0–4.5]0.43
EQ-5D0.66 [0.11–0.76]0.66 [0.23–0.73]0.84
Pain VAS 0–100 mm45.5 (26.3)48.1 (23.5)0.55
Fatigue VAS 0–100 mm41.5 (29.8)40.0 (28.4)0.78
RAID score4.7 (2.3)4.4 (2.1)0.53
PROMIS HAQ36.3 [13.8–58.8]29.5 [17.5–48.8]0.78
SF-36 PCS32.5 (7.9)36.6 (9.7)0.37
SF-36 MCS48.6 (11.9)49.3 (10.3)0.75
  • Bold indicates p-values less than 0.05.

  • Values are median [25th–75th centiles] or mean (SD), unless otherwise indicated.

  • *Original disease activity score based on ESR, patient global, 44 SJC and Ritchie Articular Index.

  • †Ultrasonography (US) semiquantitative scoring system with ranges 0–3 for grey scale (GS) and power Doppler (PD) in 36 joints and 4 tendons. (Total US joint score, range: 0–216. Total US tendon score, range: 0–24.)

  • ACPA, anticitrullinated peptide antibody; CRP, C reactive protein; DAS, disease activity score; EQ-5D, EuroQol-5 Dimensions (UK weighted); ESR, erythrocyte sedimentation rate; MCS, Mental Components Summary; PCS, Physical Components Summary; PROMIS HAQ, Patient-Reported Outcome Measurement Information System Health Assessment Questionnaire; RA, rheumatoid arthritis; RAID, Rheumatoid Arthritis Impact of Disease (range from 0 to 10, with higher scores indicating greater impact of disease); RF, rheumatoid factor; SF-36, 36-item Short Form Health Survey; SJC, swollen joint count; VAS, Visual Analogue Scale.