Spinal radiographic progression in axial spondyloarthritis and the impact of classification as nonradiographic versus radiographic disease: Data from the Swiss Clinical Quality Management cohort

PLoS One. 2020 Mar 20;15(3):e0230268. doi: 10.1371/journal.pone.0230268. eCollection 2020.

Abstract

Objective: To investigate whether spinal radiographic progression relates to structural damage at the sacroiliac level in axial spondyloarthritis (axSpA).

Methods: Patients classified as nonradiographic (nr-) and radiographic (r-) axSpA in the Swiss Clinical Quality Management cohort with radiographs performed every 2 years, scored according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS), were included. The relationship between classification status and spinal progression during 2 years was investigated using binomial generalized estimating equations models with adjustment for sex, ankylosing spondylitis disease activity score (ASDAS) and tumour necrosis factor inhibitor treatment. Baseline spinal damage was considered an intermediate variable and included in sensitivity analyses.

Results: In total, 88 nr-axSpA and 418 r-axSpA patients contributed to data for 725 radiographic intervals. R-axSpA patients were more frequently male, had a longer disease duration and higher structural damage at baseline. Mean (SD) mSASSS change over 2 years was 0.16 (0.62) units in nr-axSpA and 0.92 (2.78) units in r-axSpA, p = 0.01. Nr-axSpA was associated with a significantly lower progression in 2 years (defined as an increase in ≥2 mSASSS units) in adjusted analyses (OR 0.33, 95%CI 0.13; 0.83), confirmed with progression defined as the formation of ≥1 syndesmophyte. Mediation analyses revealed that sacroiliitis exerted its effect on spinal progression indirectly by being associated with the appearance of a first syndesmophyte (OR 0.09, 95%CI 0.02; 0.36 for nr-axSpA vs r-axSpA). Baseline syndesmophytes were predictors of further progression.

Conclusion: Spinal structural damage is mainly restricted to patients with r-axSpA, leading to relevant prognostic and therapeutic implications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cervical Vertebrae / diagnostic imaging
  • Female
  • Humans
  • Lumbar Vertebrae / diagnostic imaging
  • Male
  • Middle Aged
  • Radiography / methods*
  • Radiography / standards
  • Spondylitis, Ankylosing / classification
  • Spondylitis, Ankylosing / diagnostic imaging*

Grants and funding

The Swiss Clinical Quality Management (SCQM) registries for rheumatic diseases are run by the SCQM Foundation which is supported by by the Swiss Society of Rheumatology and by AbbVie, Celgene, Lilly, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Samsung, Sandoz, Sanofi, UCB, and has received project-based financial supports from the Arco Foundation, Switzerland, as well as from the Swiss Balgrist Society, Switzerland. This study was supported by the Stiftung für Rheumaforschung, Zurich, Switzerland, and by a commercial funder, Merck Sharp & Dohme Corp., through a research grant from the Investigator-Initiated Studies Program to SCQM. This does not alter our adherence to PLOS ONE policies on sharing data and materials. With this funding, SCQM provided support in the form of salaries for specific roles of authors MH (statistical analysis) and AS (project administration and statistical supervision) as well as XB and MdH (scoring of spinal radiographs). The funders did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The complete roles of these authors are articulated in the “author contributions” section.