Demographic, clinical and laboratory features at diagnosis of A-DS (n=33) and JIA (n=21). Where data are presented as median and range, statistical significance was determined using the Mann-Whitney U test. For data presented as a proportion of the total population, statistical significance was calculated using the χ2 test or Fisher exact test
| Characteristic | A-DS n=33 | JIA n=21 | p value |
| Age, median in years (range) | 11.4 (0.3–19.2) | 6.3 (1.1–16) | p<0.001 |
| Gender, n male (% male) | 18 (55) | 11 (52) | ns |
| AJC, n (range) | 3 (0–18) | 4 (1 – 13) | ns |
| RJC, n (range) | 4 (0–12) | 1 (0–10) | p<0.05 |
| *Small joint involvement, n (%) | 28 (85) | 9 (43) | p<0.01 |
| Raised ESR at diagnosis, n (%) | 8† (32) | 15 (71) | p<0.01 |
| Raised CRP at diagnosis, n (%) | 3‡ (10) | 6 (29) | ns |
| ANA positive, n (%) | 0 (0) | 5 (24) | p<0.01 |
| RF positive, n (%) | 0 (0) | 1 (5) | ns |
*Small joint involvement is defined as evidence of active inflammation in the metacarpophalangeal, proximal and/or distal interphalangeal joints of the hands.
†A-DS cohort of n=25.
‡A-DS cohort of n = 29 (n numbers less than total cohort as results missing).
A-DS, Arthropathy of Down syndrome; AJC, Active joint count;ANA, anti-nuclear antibody; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; JIA, Juvenile Idiopathic Arthritis ; RF, rheumatoid factor; RJC, Restricted joint count; n, number; ns, not significant.