Table 5 Clinical characteristics and HLA-B27 test results of patients with nonradiographic axial spondyloarthritis across geographic regions

Laboratory-confirmed SpA (HLA-B27)

0.062

 Positive, n (%)

15 (45.45 %)

56 (63.64 %)

61 (43.57 %)

 Negative, n (%)

6 (18.18 %)

10 (11.36 %)

37 (26.43 %)

 Results not available, n (%)

12 (36.36 %)

22 (25.00 %)

42 (30.00 %)

Laboratory-confirmed SpA (excluding missing) (HLA-B27)

0.019

 Positive, n (%)

15 (71.43 %)

56 (84.85 %)

61 (62.24 %)

 Negative, n (%)

6 (28.57 %)

10 (15.15 %)

37 (37.76 %)

Family history of SpA

0.231

 Yes, n (%)

9 (27.27 %)

18 (20.45 %)

43 (30.71 %)

 No, n (%)

22 (66.67 %)

67 (76.14 %)

86 (61.43 %)

 Results not available, n (%)

2 (6.06 %)

3 (3.41 %)

11 (7.86 %)

Family history of SpA (excluding missing)

0.125

 Yes, n (%)

9 (29.03 %)

18 (21.18 %)

43 (33.33 %)

 No, n (%)

22 (70.97 %)

67 (78.82 %)

86 (66.67 %)

NSAID response

0.264

 Positive, n (%)

22 (66.67 %)

64 (72.73 %)

93 (66.43 %)

 Negative, n (%)

7 (21.21 %)

22 (25.00 %)

42 (30.00 %)

 Results not available, n (%)

4 (12.12 %)

2 (2.27 %)

5 (3.57 %)

Most recent CRP level

0.214

 Not elevated (<3.5 mg/L), n (%)

10 (30.30 %)

21 (23.86 %)

37 (26.43 %)

 Elevated (≥3.5 mg/L), n (%)

18 (54.55 %)

55 (62.50 %)

80 (57.14 %)

 Results not available, n (%)

5 (15.15 %)

12 (13.64 %)

23 (16.43 %)

Most recent CRP level (excluding missing)

0.104

 Not elevated (<3.5 mg/L), n (%)

10 (35.71 %)

21 (27.63 %)

37 (31.62 %)

 Elevated (≥3.5 mg/L), n (%)

18 (64.29 %)

55 (72.37 %)

80 (68.38 %)

Most recent ESR level

<0.001

 Not elevated (<28 mm/h), n (%)

20 (60.61 %)

66 (75.00 %)

69 (49.29 %)

 Elevated (≥28 mm/h), n (%)

9 (27.27 %)

17 (19.32 %)

66 (47.14 %)

 Results not available, n (%)

4 (12.12 %)

5 (5.68 %)

5 (3.57 %)

Most recent ESR level (excluding missing)

<0.001

 Not elevated (<28 mm/h), n (%)

20 (68.97 %)

66 (79.52 %)

69 (51.11 %)

 Elevated (≥28 mm/h), n (%)

9 (31.03 %)

17 (20.48 %)

66 (48.89 %)