Session Type: ACR Concurrent Abstract Session
Session Time: 2:30PM-4:00PM
Background/Purpose: Making the diagnosis of axial spondyloarthritis (axSpA) may be difficult. Antibodies against CD74 have been shown to be present in 2/3 of patients with long established axial SpA. InterSpA is an international multicenter study, conducted to compare the sensitivity and specificity of anti-CD74 and HLA-B27 in patients with axSpA of recent onset.
Methods: Patients between 18 and 45 years suffering from inflammatory back pain (IBP) for maximally 2 years were recruited. The presence of ankylosing spondylitis, additional inflammatory rheumatic disorders and biologic therapy were exclusion criteria. MRI of the sacroiliac joint was performed in all patients; HLA-B27 was detected by genotyping and anti-CD74 using a CE certified kit of Aesku Diagnostics (Wendelsheim, Germany). The sensitivity of anti-CD74 and HLA-B27 were calculated in patients fulfilling the imaging arm of ASAS criteria, in all patients fulfilling ASAS criteria and in 100 blood donors. Both the MRI reading as well as the laboratory procedures were performed blinded.
Results: 205 patients suffering from IBP were recruited. There were 40 recruiting failures, and complete data sets are currently available of 122 patients (mean age 29 years, mean duration of IBP 13 months, 56% male). Sacroiliitis was diagnosed by the expert reader in 67 % and HLA-B27 was positive in 69 % of the patients. 23 patients fulfilled the ASAS criteria of axSpA by the imaging arm only, 59 by both the imaging and clinical arm and 22 by the clinical arm only. The sensitivities of IgA anti-CD74, IgG anti-CD74 and HLA-B27 were 64.6%, 24.4% and 75% in the axSpA patients fulfilling the imaging arm, 65.4%, 23.1% and 80.7% in the patients fulfilling ASAS criteria, and 3%, 5% and 8% in the blood donors. The likelihood ratios are 21.5 (IgA anti-CD74), 4.9 (IgG anti-CD74) and 9.4 (HLA-B27) when considering the patients fulfilling the imaging arm, and 21.8 (IgA anti-CD74), 4.6 (IgG anti-CD74) and 10.1 (HLA-B27) when considering all patients fulfilling ASAS criteria.
To cite this abstract in AMA style:Witte T, Riechers E, Baerlecken NT, Baraliakos X, Achilles-Mehr Bakhsh K, Aries P, Bannert B, Becker K, Brandt-Juergens J, Braun J, Ehrenstein BP, Euler H, Fleck M, Hein R, Karberg K, Koehler L, Matthias T, Max R, Melzer A, Meyer-Olson D, Rech J, Rockwitz K, Rudwaleit M, Schweikhard E, Sieper J, Stille C, von Hinüber U, Wagener P, Weidemann H, Zinke S. Sensitivity and Specificity of Autoantibodies Against CD74 in Early Axial Spondyloarthritis [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/sensitivity-and-specificity-of-autoantibodies-against-cd74-in-early-axial-spondyloarthritis/. Accessed December 2, 2020.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/sensitivity-and-specificity-of-autoantibodies-against-cd74-in-early-axial-spondyloarthritis/