Table 1

Imaging abnormalities ‘typical of axSpA’ observed in the axSpA and mechanical chronic back pain groups

CBP n=98‡axSpA n=100p
XraysPelvic XraysLesionsErosion (y/n)*9/97(9.3%)35(35.0 %)<0.001§
Sclerosis (y/n)21/97(21.6%)50(50.0%)<0.001
Joint widening (y/n)13/97 (13.4%)25 (25.0%)NS
Joint narrowing (y/n)11/97 (11.3%)21 (21.0%)NS
Partial ankylosis (y/n)7/97 (7.2%)11 (11.0%)NS
Total ankylosis (y/n)03 (3.0%)NS
At least a gradetwounilateral26/96(27.1%)54(54%)<0.001
Modified NY criteria11/95(11.6%)35(35.0%)<0.001
Spine XraysLesionsNumber of erosions0.4 (0.8)0.3 (0.5)NS
Number of sclerosis lesions0.4 (1.6)0.5 (1.4)NS
Number of squaring lesions0.01(0.1)0.2(0.8)0.037
Number ofpatientswith at least one full bone bridge2 (2.1%)5 (5.0%)NS
MRIInflammatory lesionsSacroiliac jointsAt least one inflammatory lesion24/95(25.3%)40(40.0%)0.028
ASAS definition of MRI sacroiliitis8/95(8.4%)35(35.0%)<0.001
ASAS definition of MRI sacroiliitis AND deep lesion1/95(1.1%)17(17%)<0.001
ASAS definition of MRI sacroiliitis AND intense lesion†2/95(2.1%)20(20%)<0.001
ASAS definition of MRI sacroiliitis AND (deep OR intense lesion)†3/95(3.2%)24(24%)<0.001
ASAS definition of MRI sacroiliitis AND (deep AND intense lesion)†013(13%)<0.001
SpineAt leastoneinflammatory lesion44 (44.9%)52/99 (52.5%)NS
At leastthreeinflammatory lesions (ASAS definition of positive spine MRI)33 (33.7%)44/99 (44.4%)NS
At leastfiveinflammatory lesions25 (25.5%)30/99 (30.3%)NS
Structural lesionsSacroiliac jointsAt leastonestructural lesion16/95 (16.8%)24 (24%)NS
At leastthreeerosions10/95(10.5%)32(32%)<0.001
At leastthreefatty lesions11/95(11.6%)29(29%)0.004
At leastfiveerosions or fatty lesions13/95(13.7%)33(33%)0.002
SpineAt leastonestructural lesion49 (50.0%)42/99 (42.4%)NS
At leastthreeerosions6 (6.1%)7/99 (7.1%)NS
At leastthreefatty lesions21 (21.4%)15/99 (15.2%)NS
At leastfivefatty lesions12 (12.2%)9/99 (9.1%)NS
At leastfivestructural lesions (erosions OR fatty lesions)19 (19.4%)11/99 (11.1%)NS
  • *Results are presented as n(%) for dichotomous variables and as mean (SD) for continuous variables.

  • †According to the SPARCC scoring of the SIJ.

  • ‡In case no denominator is indicated, the available images are n=98 for CBP and n=100 for axSpA.

  • §Significant results are highlighted in bold.

  • ASAS, Assessment of SpondyloArthritis international Society; CBP, chronic back pain; NY, New York; SPARCC, Spondyloarthritis Research Consortium of Canada index; axSpA, axial Spondyloarthritis.