Two hundred twenty-three patients were enrolled in the study (Table 1) with 1.4 years median follow-up time (IQR 0-2.9 years). The prevalent diagnosis was ERA (62%) followed by PsA, UA and IBD-A (18%, 14%, 6%, respectively). Twelve ERA patients and 1 UA patient developed IBD. Amongst the entire JSpA cohort, as well as in patients with UA, sex was equally distributed (50% male). The ERA subcohort had the highest male prevalence (59%), whereas the PsA subset showed a female preponderance (20% male) (distribution of sex by group, p<0.05). The rate of HLA-B27 positivity of the whole cohort was 38%; those with ERA had the highest rate of HLA-B27 positivity whereas non-ERA patients had a significantly lower rate (46% vs. 21%; p=0.00). HLA-B27 data was missing from 23 of 223 JSpA patients (10%): 6 ERA, 7 PsA, 4 UA and 6 IBD.
Table 1. General cohort characteristics.
|
All JSpA
(N=223)
|
ERA
(N=138)
|
PsA
(N=41)
|
UA
(N=30)
|
IBD-A
(N=14)
|
p-value*
|
Males
|
111/223 (50%)
|
81/138 (59%)
|
8/41 (20%)
|
16/30 (53%)
|
6/14 (43%)
|
0.000
|
HLA-B27+ **
|
75/200 (38%)
|
61/132 (46%)
|
4/34 (12%)
|
9/26 (35%)
|
1/8 (12%)
|
0.001
|
Uveitis
|
24/223 (11%)
|
18/138 (13%)
|
3/41 (7%)
|
2/30 (7%)
|
1/8 (7%)
|
0.735
|
HLA-B27+ U †
|
10/22 (45%)
|
8/18 (44%)
|
0/2 (0%)
|
1/1 (100%)
|
1/1 (100%)
|
0.330
|
Symptomatic-U
|
19/24 (79%)
|
15/18 (83%)
|
2/3 (67%)
|
1/2 (50%)
|
1/1 (100%)
|
0.438
|
Enthesitis-related arthritis (ERA), psoriatic juvenile idiopathic arthritis (PsA), undifferentiated juvenile idiopathic arthritis (UA), arthropathies associated with inflammatory bowel disease (IBD-A), juvenile spondyloarthritis (JSpA), number of patients (N). HLA-B27+-Uveitis (HLA-B27+-U). Symptomatic-Uveitis (Symptomatic-U). * p value for Fischer’s exact test comparing distribution between JSpA subcohorts. **HLA-B27 status not available for 23 subjects – 6 ERA, 7 PsA, 4 UA, and 6 IBD-A. †Denominator is number of uveitis patients with HLA-B27 status known.
Uveitis occurred in twenty-four patients (11%) in the JSpA cohort (JSpA-U) (Table 1). Patients with uveitis had a median age at diagnosis of 7.8 years (IQR 5.4-12.4 years). There was no statistically significant difference in uveitis prevalence between all JSpA subcohorts nor when ERA patients were compared to all others (p=0.19, data not shown). Half of those with uveitis were male, both in the entire JSpA cohort and the ERA subcohort (46% and 50%, respectively), whereas PsA patients with uveitis were mostly female (67%). The rate of HLA-B27 positivity was 45% amongst JSpA-U (22/24 subjects with available data) and varied between subsets (p=0.001). When the missing HLA-B27 from each subgroup was analyzed as all positive or all negative, the difference in HLA-B27 distribution between subgroups persisted (p=0.092, p=0.001) (data not shown). The overall prevalence of symptomatic uveitis was 79% and did not vary significantly between subgroups. Considering all non-ERA patients, 6 of 85 had uveitis (7% non-ERA vs 13% ERA; p=0.187), which was symptomatic in 4 cases (67% non-ERA vs 83% ERA; p=0.568).
We further investigated the type of "ever" ocular symptoms reported by patients. The majority of patients had both eye pain and light sensitivity, although more patients reported red eyes than of eye pain/light sensitivity (79% and 71%, respectively).
In analysis restricted to HLA-B27+ patients, the overall uveitis prevalence was 13% (the same as the ERA subset) (Table 2). The distribution of HLA-B27+ uveitis did not vary significantly in categorical subgroup comparison or in a dichotomous comparison of ERA vs. non-ERA. The difference remained not significant in a sensitivity analysis accounting for all missing HLA-B27 as positive or negative (1 PsA, 1 UA) (p=0.161, p=0.281, data not shown). The majority of the uveitis in these ERA patients was symptomatic (88%) (Table 2).
Table 2. Patients with HLA-B27 sorted by the presence of uveitis
|
All JSpA (N=75)
|
ERA
(N=61)
|
PsA
(N=4)
|
UA
(n=9)
|
IBD-A
(n=1)
|
p-value*
|
p-value**
|
Uveitis
|
10/75 (13%)
|
8/61 (13%)
|
0
|
1/9 (11%)
|
1/1 (100%)
|
0.243
|
1.000
|
Symptomatic Uveitis
|
8/10 (80%)
|
7/8 (88%)
|
0
|
0
|
1/1 (100%)
|
0.378
|
0.636
|
Enthesitis-related arthritis (ERA), psoriatic juvenile idiopathic arthritis (PsA), undifferentiated juvenile idiopathic arthritis (UA), arthropathies associated with inflammatory bowel disease (IBD-A), juvenile spondyloarthritis (JSpA). All HLA-B27 positive patients (All HLA-B27+). HLA-B27+ patients with uveitis (HLA-B27+ U), HLA-B27+ patients with symptomatic uveitis (HLA-B27+ symptomatic U).* p value for the Fisher’s exact test comparing subcohorts. ** p value for the Fischer’s exact test ERA vs. non-ERA subsets.
The presence of HLA-B27 was not statistically associated with uveitis occurrence or with the presence of ocular symptoms (Fisher’s exact test or logistic regression) either in the JSpA-U cohort as a whole or in ERA-U subset (data not shown).