Table 5 Associations and strengths of the presence of BME and structural damage on MRI-SIJs in HLA-B27( +) and HLA-B27(−) nr-axSpA subjects, respectively (Pearson Chi-Square & phi scores)

HLA-B27( +)

n = 42

 Sclerosis ( +)

65.4% vs. 34.6%

0.001**

0.503

 Erosion ( +)

100% vs. 0%

NA

NA

 fJSW ( +)

75% vs. 25%

0.018*

0.370

 DP^a

57.1% vs. 42.9%

0.318

0.156

 TP^b

75% vs. 25%

0.018*

0.370

 Abnormal serum CRP

35.7% vs. 64.3%

0.429

0.100

 Abnormal serum ESR

63.6% vs. 36.4%

0.179

0.210

HLA-B27(–)

n = 61

 Sclerosis ( +)

32.4% vs. 67.6%

0.337

0.122

 Erosion ( +)

27.6% vs. 72.4%

0.911

0.014

 fJSW ( +)

63.6% vs. 36.4%

0.003**

0.377

 DP^a

22.7% vs. 77.3%

0.539

− 0.078

 TP^b

60% vs. 40%

0.012*

0.320

 Abnormal serum CRP

54.5% vs. 45.5%

0.524

0.100

 Abnormal serum ESR

31.3% vs. 68.7%

0.690

0.051