SAT0637 Radiographic and mri detected sacroiliitis is more often observed in patients with lumbosacral transitional vertebra in the desir cohort. (12th June 2018)

• Record Type: Journal Article
• Authors: Carvajal Alegria, G.; Voirin-Hertz, M.; Garrigues, F.; Simon, A.; Feydy, A.; van der Heijde, D.; Reijnierse, M.; Loeuille, D.; Claudepierre, P.; Marhadour, T.; Saraux, A.
• Is Part Of: Annals of the rheumatic diseases. Volume 77(2018)Supplement 2
• Page Start: 1170
• Page End: 1170
• Publication Date: 2018-06-12
• Subjects: Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2018-eular.4756
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Background: Lumbosacral transitional vertebra (LSTV) is a congenital anomaly of the lumbosacral transition reported in 16% to 36% of the general population. One study reported low clinical relevance of LSTV in the early diagnosis of axial spondyloarthritis (axSpA), but data remains scarce. Objectives: Our objectives were to evaluate the association of LSTV with sacroiliitis on conventional radiographs (CR) and magnetic resonance imaging (MRI) in a population with inflammatory back pain (IBP) suspected of axSpA. Methods: Baseline pelvic and lumbar CR of DESIR cohort patients (18–50 years, IBP≥3 months but <3 years and suspicion of axSpA) were analysed by readers blinded to clinical and other radiologic information. Baseline sacroiliac joint MRI had been read for sacroiliitis according to the ASAS definition. Radiographic sacroiliitis was defined according to the modified New York classification (mNYc). Unilateral sacroiliitis was defined as at least grade 2 according to the mNYc. LSTV were defined on radiographs, according to Castellvi classification: 0 normal; 1 enlarged transverse processes (a=unilateral, b=bilateral); 2 pseudo-articulation with the sacral bone (a=unilateral, b=bilateral); 3 fusion with the sacral bone (a=unilateral, b=bilateral); 4 pseudo-articulation on one side and fusion on the other. Imaging data collected at inclusion were compared in patients with LSTV versus patients without using Chi-square test or exact Fischer's test when appropriate. Results: 688 patients with available CR enabling LSTV analysis were studied, 47% were men, mean age was 33 years, 64% fulfilled ASAS criteria. Among the 688 patients 29.1% presented LSTV. Number and percentages of patients with different classes of LSTV are presented in Table I. Patients with LSTV had more often sacroiliitis on CR than patients without, respectively 27% and 19% (p=0.013). Patients with LSTV had more often sacroiliitis on MRI (figure 1) than patients without, respectively 39% and 29% (p=0.019). Presence of fusion on the right transverse process was associated with both right (p=0.001) and left (p=0.001) sacroiliitis on CR. Presence of fusion on the left transverse process was associated with sacroiliitis in CR on both right (p=0.006) and left (p=0.001) sides. Conclusions: LSTV is observed in 29.1% of patients from the DESIR cohort, as reported in the literature and is associated with sacroiliitis on conventional radiography and MRI. Further study is mandatory to understand if this is based on mechanical stress or AxSpA and to assess the potential bias of LSTV in axSpA diagnosis. Disclosure of Interest: None declared