Table 1

Baseline clinical and MRI characteristics of all patients and separately for the patients that have and have not developed clinical arthritis during follow-up

All patients
n=150*
No arthritis during follow-up
(n=119)
Arthritis during follow-up
(n=30)
Clinical characteristics
Age in years, mean (SD)43.2 (12.9)43.1 (12.8)43.9 (13.7)
Female, n (%)109 (72.7)87 (73.1)22 (73.3)
Family history positive for RA, n (%)51 (34.0)38 (31.9)12 (40.0)
Symptom duration† in weeks, med (IQR) (n=141)18 (9–30)18 (10–31)17 (8–30)
Gradual symptom onset (>1 week) (n=149)31 (20.8)95 (80.5)22 (73.3)
Localisation of initial symptoms (n=149)
 Small joints, n (%)127 (85.2)107 (90.7)19 (63.3)
 Small and large joints, n (%)15 (10.1)6 (5.1)9 (30.0)
 Large joints, n (%)7 (4.7)5 (4.2)2 (6.7)
Localisation of initial symptoms
 Upper extremities, n (%)108 (72.0)88 (73.9)20 (66.7)
 Upper and lower extremities, n (%)28 (18.7)21 (17.6)7 (23.3)
 Lower extremities, n (%)14 (9.3)10 (8.4)3 (10.0)
Symmetrical localisation of initial symptoms, n (%) (n=149)110 (73.8)91 (77.1)19 (63.3)
Morning stiffness ≥60 min at inclusion, n (%) (n=144)53 (36.8)38 (33.6)15 (50.0)
68-TJC, med (IQR) (n=146)5 (3–10)6 (3–10)5 (3–7.5)
BMI in kg/m2, mean (SD) (n=149)26.6 (5.2)26.5 (5.0)26.7 (6.1)
Present smoker, n (%)38 (25.3)29 (24.4)9 (30.0)
CRP level in mg/L, med (IQR)0 (0–4.6)0 (0–4)1.5 (0–14.5)
CRP level >5 mg/L, n (%)31 (20.7)21 (17.6)10 (33.3)
RF-positive (>3.5 IU/mL), n (%)33 (22.0)15 (12.6)18 (60.0)
ACPA-positive (>7 U/mL), n (%)24 (16.0)8 (6.7)16 (53.3)
MRI characteristics
MRI categorised into positive or negative for any subclinical inflammation and for specific inflammatory features
All patients
n=144*
No arthritis during follow-up
(n=116)
Arthritis during follow-up
(n=27)
Presence of any MRI-detected inflammation, n (%)66 (45.8)44 (37.9)22 (81.5)
 Only synovitis, n (%)9 (6.3)9 (7.8)0 (0)
 Only BME, n (%)12 (8.3)10 (8.6)2 (7.4)
 Only tenosynovitis, n (%)15 (10.4)7 (6.0)8 (29.6)
 Synovitis and BME, n (%)3 (2.1)2 (1.7)1 (3.7)
 Synovitis and tenosynovitis, n (%)18 (12.5)12 (10.3)6 (22.2)
 BME and tenosynovitis, n (%)2 (1.4)1 (0.9)1 (3.7)
 Synovitis, BME and tenosynovitis, n (%)7 (4.9)3 (2.6)4 (14.8)
Presence of MRI-detected synovitis, n (%)37 (25.7)26 (22.4)11 (40.7)
Presence of MRI-detected BME, n (%)24 (16.7)16 (13.8)8 (29.6)
Presence of MRI-detected tenosynovitis, n (%)42 (29.2)23 (19.8)19 (70.4)
  • 38 patients (25.3%) were positive for ACPA and/or RF.

  • The median total RAMRIS inflammation score was 2 (IQR 1–5); the total RAMRIS scores for synovitis, BME and tenosynovitis were 1 (IQR 0–2.5), 0.5 (IQR 0–1.5) and 0 (IQR 0–1.5), respectively. Characteristics were not compared between the groups of patients that have and have not developed clinical arthritis during follow-up because the patients have different follow-up durations.

  • *One patient that developed gout during follow-up was excluded from further analyses as the patient did not belong to the non-arthritis group and the diagnosis was outside the spectrum of chronic arthritis/RA.

  • †Duration since the start of symptoms.

  • ACPA, anticitrullinated peptide antibodies; BME, bone marrow oedema; BMI, body mass index; med, median; CRP, C reactive protein; n, number; RA, rheumatoid arthritis; RAMRIS, RA MRI scoring system; RF, rheumatoid factor; TJC, tender joint count.