Male spondyloarthritis patients and those with longer disease duration have less severe disc degeneration: propensity score-matched comparison

Abstract

Objective Using whole-spine sagittal T2 magnetic resonance imaging (MRI) we aimed to compare the severity and prevalence of disc degeneration (DD) in axial spondyloarthritis (SpA) patients versuss the general population, and to determine any association between spinal inflammation, structural changes, mobility and DD among SpA patients. Methods Two prospectively collected cohorts of SpA patients (n = 411) and general population (n = 2007) were recruited. Eventually 967 participants from the populational cohort and 304 participants from the SpA cohort were analysed. 219 match pairs were generated by propensity-score matching. Imaging parameters including Pfirrmann grading, disc herniation, high intensity zone (HIZ), Schmorl’s node (SN), Modic change (MC) and anterior marrow change were studied and compared from C2/3 to L5/S1. DD was defined with Pfirrmann grade 4 or 5. Demographic factors including age, sex and BMI were collected. Multivariable linear regression was used to determine association between spinal inflammation (Spondyloarthritis research consortium of Canada (SPARCC) spine MRI index), structural changes (Modified Stoke ankylosing spondylitis spinal score (mSASSS)), and mobility (Bath ankylosing spondylitis metrology index (BASMI)) with lumbar Pfirrmann score. Results SpA patients had lower prevalence of DD (p < 0.001). The disease-stage stratified regression model showed SPARCC spinal MRI index was associated with higher lumbar Pfirrmann scores in early disease (β = 0.196, p = 0.044), where mSASSS was associated with lower lumbar Pfirrmann scores in later disease (β=-0.138, p = 0.038). Male had higher mSASSS (p < 0.001) and lower odds of whole spine DD (OR = 0.622, p = 0.028). Conclusion SpA patients had lower DD severity than the population. Males had higher mSASSS scores, and increased mSASSS at later disease was associated with less severe DD.