Early predictors of juvenile sacroiliitis in enthesitis-related arthritis.
OBJECTIVE
To identify early predictors of sacroiliac (SI) involvement in a cohort of patients with enthesitis-related arthritis (ERA).


METHODS
During a 7-year followup period, all consecutive patients fulfilling the ILAR classification criteria for ERA were enrolled. Data collected included demographic, clinical and laboratory variables at disease onset, at the onset of inflammatory back pain, and at the last available followup visit. Pelvis radiographs and dynamic magnetic resonance imaging (MRI) scans for SI joints were obtained simultaneously in all patients who developed inflammatory back pain.


RESULTS
Fifty-nine children with ERA were studied; 40 male, 19 female; median age at disease onset 9 years 4 months (range 6 yrs 6 mo - 13 yrs 3 mo). At a median interval after disease onset of 1 year 3 months, 21 children reported symptoms of inflammatory back pain. In all cases, radiographs of SI joints were negative, while dynamic MRI revealed acute sacroiliitis in 17 cases. Multivariate analysis showed that the early predictors of SI were the number of active joints (p < 0.03) and the number of active entheses (p < 0.001) at onset.


CONCLUSIONS
In our cohort, roughly 30% of children with ERA/juvenile idiopathic arthritis develop clinical and MRI evidence of sacroiliitis, detectable with dynamic MRI as early as 1 year after disease onset. Additional data from larger case series are needed to assess the specificity and sensitivity of this technique in the early phase of the disease and to confirm the rate of SI involvement reported in this cohort.
Pagnini
Ilaria
I
Department of Paediatric Rheumatology, University of Florence, Anna Meyer Children's Hospital, Viale Pieraccini 24, 50139 Florence, Italy. dott.pagnini@alice.it
Savelli
Sara
S
Matucci-Cerinic
Marco
M
Fonda
Claudio
C
Cimaz
Rolando
R
Simonini
Gabriele
G
D000293:Adolescent; D001171:Arthritis, Juvenile / Q000000981:diagnostic imaging / Q000473:pathology*; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D015999:Multivariate Analysis; D011859:Radiography; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D058566:Sacroiliitis / Q000000981:diagnostic imaging / Q000473:pathology*; D012720:Severity of Illness Index