Table 1 Baseline and follow-up features (4 years) of the patients in the registry

Total no. of eligible patients with follow-up data available

400

81

Female, n (%)

258 (65.5%)

47 (58.0%)

Age at disease onset in years, mean (SD)

11 years (SD 2.9)

-

Time between symptom onset and first visit to pediatric rheumatology in months, mean

5.3 months (SD 5.2)

-

Inclusion to the registry after first visit to pediatric rheumatology, mean

5.8 months (SD 3.2)

-

HLA-B27 positive^a

21 (13.2%)

5 (13.5%)

Physician’s global assessment, NRS, mean (SD)^b

2.0 (1.9)

0.9 (1.7)

Patient’s global assessment, NRS, mean (SD)^b

2.5 (2.4)

2.2 (2.5)

Patients’ pain, NRS, mean (SD)^b

2.6 (2.7)

1.9 (2.6)

C-HAQ, NRS, mean (SD)^b

0.3 (0.4)

0.2 (0.3)

Arthritis

79 (20.8%)

13 (16.9%)

 -Peripheral

64 (16.9%)

9 (11.7%)

 -Sacroiliitis

20 (5.3%)

4 (5.2%)

Number of patients (%) meeting the classification criteria for

 -Psoriatic arthritis

5 (1.3%)

3 (4.0%)

 -Enthesitis-related arthritis

3 (0.8%)

3 (4.0%)

Skin disease (psoriasis, acne, PPP)

61 (15.6%)

14 (17.7%)

IBD

2 (0.5%)

5 (6.6%)