Development and Validation of 3 Preliminary MRI Sacroiliac Joint Composite Structural Damage Scores in a 5-year Longitudinal Axial Spondyloarthritis Study
Marie Wetterslev, Mikkel Østergaard, Inge Juul Sørensen, Ulrich Weber, Anne Gitte Loft, G. Kollerup, Lars Juul, Gorm Thamsborg, Ole Rintek Madsen, Jakob Møllenbach Møller, Susanne Juhl Pedersen
Abstract
Objective. In axial spondyloarthritis (axSpA), sacroiliac joint (SIJ) erosion is often followed by fat metaplasia in an erosion cavity (backfill), and subsequently ankylosis. We aimed to combine the Spondyloarthritis Research Consortium of Canada (SPARCC) SIJ structural score for erosion, backfill, and ankylosis into 3 versions of a novel preliminary axSpA magnetic resonance imaging (MRI) SIJ Composite Structural Damage Score (CSDS) and to test these. Methods. Thirty-three patients with axSpA, followed for 5 years after initiation of tumor necrosis factor inhibitor, had MRIs of the SIJs at baseline, and yearly thereafter. Three versions of CSDS were calculated based on different weightings of erosion, backfill, and ankylosis: (1) equal weighting: CSDS equal = (erosion × 0.5) + backfill + ankylosis; (2) advanced stages weighting more: CSDS stepwise = (erosion × 1) + (backfill × 4) + (ankylosis × 6); and (3) advanced stages overruling earlier stages (“hierarchical”) with “<” meaning “overruled by”: CSDS hierarchical = (erosion × 1) < (backfill × 4) < (ankylosis × 6). Results. At baseline, all CSDS correlated positively with SPARCC fat and ankylosis scores and modified New York radiography grading, and negatively with the Bath Ankylosing Spondylitis Disease Index and SPARCC SIJ inflammation scores. CSDS stepwise and CSDS hierarchical (not CSDS equal ) correlated positively with symptom duration and the Bath Ankylosing Spondylitis Metrology Index, and closer with SPARCC ankylosis score and modified New York radiography grading than CSDS equal . The adjusted annual progression rate for CSDS stepwise and CSDS hierarchical (not CSDS equal ) was higher the first year compared with fourth year ( P = 0.04 and P = 0.01). Standardized response mean (baseline to Week 46) was moderate for CSDS hierarchical (0.64) and CSDS stepwise (0.59) and small for CSDS equal (0.25). Conclusion. Particularly CSDS stepwise and CSDS hierarchical showed construct validity and responsiveness, encouraging further validation in larger clinical trials. The potential clinical implication is assessment of SIJ damage progression by 1 composite score.