Development and Evaluation of the Combined Ankylosing Spondylitis Spine Score (CASSS) for the Assessment of Spinal Radiographic Outcome

Fiona Maas¹, Anneke Spoorenberg^1,2, Elisabeth Brouwer¹, Hendrika Bootsma³, Reinhard Bos², Freke Wink² and Suzanne Arends^1,2, ¹Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands, ²Rheumatology, Medical Center Leeuwarden, Leeuwarden, Netherlands, ³Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, The Netherlands, Groningen, Netherlands

Meeting: 2016 ACR/ARHP Annual Meeting

Date of first publication: September 28, 2016

Keywords: Ankylosing spondylitis (AS), outcome measures and radiography

Session Information

Date: Sunday, November 13, 2016

Title: Spondylarthropathies and Psoriatic Arthritis – Clinical Aspects and Treatment - Poster I: Axial and Peripheral Spondyloarthritis – Clinical Aspects, Imaging and Treatment

Session Type: ACR Poster Session A

Session Time: 9:00AM-11:00AM

Background/Purpose: Spinal radiographic progression is a highly variable process in ankylosing spondylitis (AS). Our aim was to develop a combined AS spine score (CASSS) in which the cervical facet joint score is combined with the mSASSS, and to investigate the additional value of the CASSS in the evaluation of spinal radiographic progression in AS patients.

Methods: Baseline and 4-year radiographs from 98 consecutive AS patients treated with TNF-α inhibitors in the GLAS cohort were scored by two readers; vertebral bodies according to mSASSS (0-72) and cervical facet joints (C2-C7) according to the method of de Vlam (0-15). The CASSS was calculated by summing up the total scores of both methods (range 0-87) and was compared to mSASSS (gold standard) using three aspects of the OMERACT filter: feasibility, discrimination, and truth.

Results: Feasibility: Scoring cervical facet joints took a few minutes, no additional radiographs were necessary. The CASSS could be calculated in 91 (93%) and mSASSS in 94 (96%) patients. Discrimination: Both scoring methods had very good inter-observer reliability (ICC’s status scores >0.99, progression scores 0.92). Measurement error was similar for CASSS and mSASSS, smallest detectable change was 1.9 and 1.8, resp. Sensitivity to change was moderate for both methods with a standardized response mean of 0.63 for CASSS and 0.59 for mSASSS. Truth: The use of CASSS resulted in 41 (46%) patients with higher baseline scores and 22 (25%) with higher progression scores compared to mSASSS. Baseline damage of facet joints was moderately correlated with damage of vertebral bodies (rho=0.49). Radiographic progression of facet joints was not correlated with progression of vertebral bodies (rho=0.16).

Conclusion: According to the OMERACT filter, the new CASSS performed similar to mSASSS in respect to feasibility and discrimination. The CASSS showed better truth value since it provides a broader range of structural changes and captures more AS patients with progression which is very important in the evaluation of radiographic outcome in this heterogeneous and slowly progressing disease.

Disclosure: F. Maas, None; A. Spoorenberg, Abbvie, Pfizer, UCB, 2,Abbvie, Pfizer, MSD, UCB, and Novartis, 5; E. Brouwer, Roche Pharmaceuticals, 5; H. Bootsma, None; R. Bos, None; F. Wink, Abbvie, 5; S. Arends, Pfizer, 2.

To cite this abstract in AMA style:

Maas F, Spoorenberg A, Brouwer E, Bootsma H, Bos R, Wink F, Arends S. Development and Evaluation of the Combined Ankylosing Spondylitis Spine Score (CASSS) for the Assessment of Spinal Radiographic Outcome [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/development-and-evaluation-of-the-combined-ankylosing-spondylitis-spine-score-casss-for-the-assessment-of-spinal-radiographic-outcome/. Accessed .

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