Presence of spondyloarthritis associated to higher disease activity and HLA-B27 positivity in patients with early Crohn's disease: Clinical and MRI results from a prospective inception cohort.

OBJECTIVE

To determine the SpA prevalence and identify its associated factors in Crohn's disease (CD) patients receiving a systematically rheumatological and imaging assessment, including magnetic resonance imaging (MRI) of the sacroiliac joints and spine.

METHODS

CD patients either naive to biologics or without them for three months prior enrollment were recruited in a subgroup of the German Spondyloarthritis Inception Cohort (GESPIC-Crohn). A structured assessment of SpA manifestations was performed by a rheumatologist, including MRI of sacroiliac joints and spine. Demographic and clinical parameters including disease activity in CD (Harvey Bradshaw Index-HBI) and SpA (C-reactive protein - CRP, Bath Ankylosing Spondylitis Disease Activity Index, and Ankylosing Spondylitis Disease Activity Score) were collected. Univariable and multivariable logistic regression analyses were performed to identify factors associated with the presence of SpA.

RESULTS

A total of 103 patients with CD were included in the cohort. The mean CD disease duration was 1.3±2.4years and 95.1% were naïve to biologics. The most frequent musculoskeletal manifestation was back pain (65.0%), followed by chronic back pain (50.5%), and arthralgia (43.7%). Prevalence of SpA was 19.4% with slightly higher proportion of axial SpA than peripheral SpA, and higher proportion of radiographic axial SpA (7.4%) than non-radiographic axial SpA (2.8%). Changes in MRI compatible with axial SpA were found in 15 (14.7%) patients, of which 9 (81.1%) patients had the clinical diagnosis of axial SpA. HLA-B27 positivity (OR 9.02, CI 95% 2.29-35.55) and higher disease activity of CD as reflected by the HBI (OR 1.14, 95%CI 1.01-1.30) were significant and independently associated with the presence of SpA.

CONCLUSION

SpA was present in nearly one out of five patients with CD and it was associated with the expression of HLA-B27 and a higher clinical activity of CD. Our findings raise awareness to rheumatologists and gastroenterologists on the high concomitance between both diseases and may help to reduce the delay in SpA diagnosis.