Low grade radiographic sacroiliitis as prognostic factor in patients with undifferentiated spondyloarthritis fulfilling diagnostic criteria for ankylosing spondylitis throughout follow up

Abstract

Objective: To determine the rate and factors associated with ankylosing spondylitis in a cohort of patients with undifferentiated spondyloarthritides (SpA). Methods: 62 consecutive patients with undifferentiated SpA seen between 1998 and 1999 underwent clinical and imaging evaluations throughout follow up. The main outcome measure was a diagnosis of ankylosing spondylitis. Results: 50 patients with peripheral arthritis (n = 35) and inflammatory back pain (n = 24) (26 male; mean (SD) age at onset, 20.4 (8.8) years; disease duration 5.4 (5.7) years) were followed up for 3-5 years. At baseline, .90% of patients had axial and peripheral disease, while 38% had radiographic sacroiliitis below the cut off level for a diagnosis of ankylosing spondylitis (BASDAI 3.9, BASFI 2.9). At the most recent evaluation, 21 patients (42%) had ankylosing spondylitis. Two factors were associated with a diagnosis of ankylosing spondylitis in multivariate analysis: radiographic sacroiliitis grade ,2 bilateral, or grade ,3 unilateral (odds ratio (OR) = 11.18 (95% confidence interval, 2.59 to 48.16), p = 0.001), particularly grade 1 bilateral (OR = 12.58 (1.33 to 119.09), p = 0.027), and previous uveitis (OR = 19.25 (1.72 to 214.39), p = 0.001). Acute phase reactant levels, juvenile onset, and HLA-B27 showed a trend to linkage with ankylosing spondylitis (NS). Conclusions: Low grade radiographic sacroiliitis is a prognostic factor for ankylosing spondylitis in patients originally classified as having undifferentiated SpA. Low grade radiographic sacroiliitis should be regarded as indicative of early ankylosing spondylitis in patients with undifferentiated SpA.

The early disease stage in axial spondylarthritis: Results from the german spondyloarthritis inception cohort

“…Based on our results, we hypothesize that in patients with early axial SpA, male sex may be a risk factor for the development of radiographic sacroiliitis, and, therefore, for the evolution to AS. This hypothesis is consistent with the observed male predominance in AS, although a rather balanced sex distribution is often reported in uSpA (34)(35)(36)(37)(38).…”

“…A role for CRP in the development of definite radiographic sacroiliitis was also suggested in the small study by Huerta-Sil et al (38) in 50 patients with uSpA; after 3-5 years, uSpA evolved to AS in 21 of those patients. CRP was also associated with syndesmophytes in the spines of GES-PIC patients with AS.…”

From Retrospective Analysis of Patients with Undifferentiated Spondyloarthritis (SpA) to Analysis of Prospective Cohorts and Detection of Axial and Peripheral SpA

“…In 2 shorter followup studies, the proportion of patients fulfilling AS criteria 24 and 28 months after onset were 10% 22 and 36% 23 , respectively. In the Schattenkirchner and Krüger study 24 , the percentage reached 25% within 2 to 6 years, versus Huerta-Sil's finding of 42% by 3 years after symptom onset 25 . Two further studies 16,26 found AS in 25% and 36% by 5 years after onset.…”

“…Diagnosis varied from "HLA-B27-negative associated oligoarthritis" 24 to "possible ankylosing spondylitis" 16 , "possible SpA" 26 , and "undifferentiated SpA" 17,22,25 . Disease duration in various studies extended more than 10 years (i.e., the sum of the duration of the disease at baseline and the duration of followup); therefore, diagnosis of USpA does not necessarily mean early or recent SpA.…”

Do patients with non‐radiographic axial spondylarthritis differ from patients with ankylosing spondylitis?

“…Nevertheless, a subgroup of patients in a Dutch cohort developed structural changes rather early in the disease course; 20% of the patients with a history of inflammatory back pain of Ͻ2 years in duration had chronic structural changes in the SI joints (27). Although low-grade radiographic sacroiliitis has been proposed as a prognostic factor for the development of AS in patients originally classified as having undifferentiated SpA, only a minority of patients with nr-axSpA seem to develop definitive AS (28).…”