Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose
The prevalence of sacroiliitis in children with juvenile spondyloarthritis (JSpA) at diagnosis is unknown. We aimed to evaluate: 1) the prevalence of sacroiliitis at diagnosis using radiographs and MRI; and 2) the association of physical examination and a history of back pain with acute sacroiliitis, using MRI as the reference standard.
Methods
We performed a single center prospective cross-sectional study of 39 children with newly diagnosed JSpA. Children were eligible for inclusion if they were diagnosed with enthesitis-related arthritis (ERA) or psoriatic arthritis (PsA) according to the International League of Associations for Rheumatology criteria in the prior 6 months. On the same day subjects had a musculoskeletal examination and imaging, which included a single AP pelvic radiograph and a non-contrast pelvic MRI with STIR. Radiographs were scored using the modified New York criteria. Acute sacroiliitis on MRI was defined as bone marrow edema within the sacrum or adjacent ilium with or without accompanying capsulitis, enthesitis, or effusion. Univariate logistic regression was used to test the association of clinical factors with acute sacroiliitis.
Results
Mean age of the JSpA subjects was 14.0 ± 2.7 years. 49% were male and 44% were HLA-B27+. 35 and 4 children met criteria for ERA and psoriatic arthritis, respectively. Nine (23%) children had acute sacroiliitis; in 5 subjects it was bilateral. Of the 9 children with acute sacroiliitis on MRI, 7 (78%) had erosions or sclerosis on MRI and 5 (56%) had changes on conventional radiography. 2 subjects met radiologic criteria for ankylosing spondylitis. Of the subjects with acute sacroiliitis only 4 (44%) reported a history of back pain or tenderness on palpation of the sacroiliac joints. 3 (33%) and 14 (47%) of children with JSpA with and without sacroiliitis met the ASAS inflammatory back pain criteria. Male sex, hip arthritis, alternating buttock pain, higher c-reactive protein, HLA-B27 positivity, and decreased lateral flexion were associated with a higher odds of acute sacroiliitis, albeit statistically insignificant (Table).
Conclusion
This is the first study reporting the prevalence of acute sacroiliitis at diagnosis in children with JSpA. Sacroiliitis is common at diagnosis and may be asymptomatic. Nearly half the cases of sacroiliitis would have been missed if radiographs were the only imaging modality.
Table. Clinical features in MRI+ and MRI- subjects (N=39)
|
Clinical Feature
|
MRI+ N=9 N (%)
|
MRI- N=30 N (%)
|
p-value+
|
OR of acute sacroiliitis (95% CI)
|
|
Psoriatic arthritis |
1 (25) |
3 (75) |
0.92 |
— |
|
Enthesitis-related arthritis |
8 (23) |
27 (77) |
0.92 |
— |
|
Age (years), mean±SD |
14.0 ±2.7 |
14.0 ±2.7 |
0.97 |
1.00 (0.75, 1.32) |
|
Male |
6 (67) |
13 (43) |
0.20 |
2.62 (0.55,12.48) |
|
AJC at diagnosis, mean±SD |
1.1±1.7 |
3.4±5.4 |
0.22 |
0.79 (0.52, 1.22) |
|
Tender enthesitis count at diagnosis, mean±SD |
3.4±3.7 |
4.2±4.2 |
0.63 |
0.95 (0.78, 1.16) |
|
Hip arthritis |
1 (11) |
3 (10) |
0.92 |
1.13 (0.10, 12.36)
|
|
Patient-reported |
|
|||
|
Back pain |
4 (44) |
18 (60) |
0.68 |
0.53 (0.12, 2.40) |
|
Back pain ≥ 3 months |
2 (22) |
10 (33) |
0.84 |
0.57 (0.10, 3.27) |
|
Insidious onset of back pain |
2 (22) |
11 (37) |
0.42 |
0.49 (0.09, 2.81) |
|
Back pain Improves with activity |
2 (22) |
7 (23) |
0.95 |
0.94 (0.16, 5.59) |
|
Alternating buttock pain |
3 (33) |
6 (20) |
0.41 |
1.68 (0.38, 10.40) |
|
AM back stiffness >30 min |
2 (22) |
13 (43) |
0.59 |
0.65 (0.14, 3.12) |
|
Nighttime back pain |
2 (22) |
10 (33) |
0.41 |
0.49 (0.08, 2.81) |
|
Inflammatory back pain# |
3 (33) |
14 (47) |
0.48 |
0.57 (0.12, 2.72) |
|
Laboratory features |
|
|||
|
CRP at diagnosis (mg/dL)*, mean±SD
|
19.2 ±39.9 |
2.2±4.7 |
0.06 |
1.06 (0.96, 1.16) |
|
HLA-B27+ ^ |
6 (75) |
10(36) |
0.05 |
5.40 (0.91, 31.93) |
|
Physical examination |
|
|||
|
Decreased lateral flexion |
5 (56) |
14 (47) |
0.64 |
1.43 (0.32, 6.39)
|
|
Loss of lumbar lordosis
|
4 (44) |
15 (59) |
0.77 |
0.80 (0.18, 3.57) |
|
Positive FABER/Patrick’s test |
0 (0) |
6 (20) |
0.15 |
— |
|
Decreased forward flexion |
1 (11) |
0 (0) |
0.06 |
— |
|
Sacroiliac tenderness |
2 (22) |
14 (47) |
0.19 |
0.33 (0.06, 1.84)
|
|
Legend. +P-value for chi-square or t-test comparisons of clinical features between subjects who had a positive or negative MRI. #ASAS inflammatory back pain (if ≥2 of the following positive: insidious onset, improvement with exercise, no improvement with rest, nocturnal pain). *CRP within 6 weeks of diagnosis available for 29 cases. ^ HLA-B27 available for 36 cases. |
||||
Disclosure:
P. Weiss,
None;
R. Xiao,
None;
N. Chauvin,
None.
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