title: Tumor necrosis factor inhibitor therapy but not standard therapy is associated with resolution of erosion in the sacroiliac joints of patients with axial spondyloarthritis.
abstract: BACKGROUND
  Radiography is an unreliable and insensitive tool for the assessment of structural lesions in the sacroiliac joints (SIJ). Magnetic resonance imaging (MRI) detects a wider spectrum of structural lesions but has undergone minimal validation in prospective studies. The Spondyloarthritis Research Consortium of Canada (SPARCC) MRI Sacroiliac Joint (SIJ) Structural Score (SSS) assesses a spectrum of structural lesions (erosion, fat metaplasia, backfill, ankylosis) and its potential to discriminate between therapies requires evaluation.
  
  
  METHODS
  The SSS score assesses five consecutive coronal slices through the cartilaginous portion of the joint on T1-weighted sequences starting from the transitional slice between cartilaginous and ligamentous portions of the joint. Lesions are scored dichotomously (present/absent) in SIJ quadrants (fat metaplasia, erosion) or halves (backfill, ankylosis). Two readers independently scored 147 pairs (baseline, 2 years) of scans from a prospective cohort of patients with SpA who received either standard (n = 69) or tumor necrosis factor alpha (TNFα) inhibitor (n = 78) therapy. Smallest detectable change (SDC) was calculated using analysis of variance (ANOVA), discrimination was assessed using Guyatt's effect size, and treatment group differences were assessed using t-tests and the Mann-Whitney test. We identified baseline demographic and structural damage variables associated with change in SSS score by univariate analysis and analyzed the effect of treatment by multivariate stepwise regression adjusted for severity of baseline structural damage and demographic variables.
  
  
  RESULTS
  A significant increase in mean SSS score for fat metaplasia (P = 0.017) and decrease in mean SSS score for erosion (P = 0.017) was noted in anti-TNFα treated patients compared to those on standard therapy. Effect size for this change in SSS fat metaplasia and erosion score was moderate (0.5 and 0.6, respectively). Treatment and baseline SSS score for erosion were independently associated with change in SSS erosion score (β = 1.75, P = 0.003 and β = 0.40, P < 0.0001, respectively). Change in ASDAS (β = -0.46, P = 0.006), SPARCC MRI SIJ inflammation (β = -0.077, P = 0.019), and baseline SSS score for fat metaplasia (β = 0.085, P = 0.034) were independently associated with new fat metaplasia.
  
  
  CONCLUSIONS
  The SPARCC SSS method for assessment of structural lesions has discriminative capacity in demonstrating significantly greater reduction in erosion and new fat metaplasia in patients receiving anti-TNFα therapy.
authors.forename: Susanne J
authors.initials: SJ
authors.lastname: Pedersen
authors.forename: Stephanie
authors.initials: S
authors.lastname: Wichuk
authors.forename: Praveena
authors.initials: P
authors.lastname: Chiowchanwisawakit
authors.forename: Robert G
authors.initials: RG
authors.lastname: Lambert
authors.forename: Walter P
authors.initials: WP
authors.lastname: Maksymowych
mesh_terms: D000328:Adult; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012446:Sacroiliac Joint / Q000473:pathology*; D012720:Severity of Illness Index; D025241:Spondylarthritis / Q000188:drug therapy* / Q000473:pathology*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors
chemical_list: D018501:Antirheumatic Agents; D014409:Tumor Necrosis Factor-alpha
references.citation: J Rheumatol. 2011 Jul;38(7):1343-8
references.pmid: 21498484
references.citation: Ann Rheum Dis. 2014 Jun;73(6):1067-70
references.pmid: 23606704
references.citation: Arthritis Res Ther. 2012 May 24;14(3):R124
references.pmid: 22626458
references.citation: J Rheumatol. 1994 Dec;21(12):2281-5
references.pmid: 7699629
references.citation: Ann Rheum Dis. 2011 Jul;70(7):1257-63
references.pmid: 21551507
references.citation: Arthritis Rheum. 1984 Apr;27(4):361-8
references.pmid: 6231933
references.citation: Ann Rheum Dis. 2013 Jan;72(1):23-8
references.pmid: 22562977
references.citation: Arthritis Rheum. 2011 Aug;63(8):2215-25
references.pmid: 21484769
references.citation: J Rheumatol. 1994 Dec;21(12):2286-91
references.pmid: 7699630
references.citation: Ann Rheum Dis. 2009 Jun;68 Suppl 2:ii1-44
references.pmid: 19433414
references.citation: Arthritis Care Res (Hoboken). 2010 Jan 15;62(1):11-8
references.pmid: 20191486
references.citation: Ann Rheum Dis. 2005 Jan;64(1):127-9
references.pmid: 15051621
references.citation: Arthritis Rheum. 2005 Oct 15;53(5):703-9
references.pmid: 16208659