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Table 4 Clinical characteristics and HLA-B27 test results of patients with nonradiographic axial spondyloarthritis, ankylosing spondylitis, and other inflammatory back pain

From: The prevalence and clinical characteristics of nonradiographic axial spondyloarthritis among patients with inflammatory back pain in rheumatology practices: a multinational, multicenter study

 

Total (N = 914)

nr-axSpA (n = 266)

AS (n = 491)

Other IBP (n = 157)

p Value

HLA-B27 test results (when available)

    

<0.001

 Positive, n (%)

397 (72.98 %)

135 (71.43 %)

250 (82.78 %)

12 (22.64 %)

 

 Negative, n (%)

147 (27.02 %)

54 (28.57 %)

52 (17.22 %)

41 (77.36 %)

 

Years from IBP to SpA diagnosis

    

0.747

 Number of patients

179

98

27

54

 

 Mean ± SD, years

5.40 ± 7.98

5.21 ± 7.69

6.48 ± 8.53

5.19 ± 8.32

 

Family history of SpA

    

<0.001

 Yes, n (%)

220 (24.07 %)

70 (26.32 %)

132 (26.88 %)

18 (11.46 %)

 

 No, n (%)

650 (71.12 %)

180 (67.67 %)

343 (69.86 %)

127 (80.89 %)

 

 Results not available, n (%)

44 (4.81 %)

16 (6.02 %)

16 (3.26 %)

12 (7.64 %)

 

Family history of SpA (excluding missing)

    

<0.001

 Yes, n (%)

220 (25.29 %)

70 (28.00 %)

132 (27.79 %)

18 (12.41 %)

 

 No, n (%)

650 (74.71 %)

180 (72.00 %)

343 (72.21 %)

127 (87.59 %)

 

NSAID response

    

0.125

 Positive, n (%)

657 (71.88 %)

183 (68.80 %)

358 (72.91 %)

116 (73.89 %)

 

 Negative, n (%)

231 (25.27 %)

72 (27.07 %)

125 (25.46 %)

34 (21.66 %)

 

 Results not available, n (%)

26 (2.84 %)

11 (4.14 %)

8 (1.63 %)

7 (4.46 %)

 

Most recent CRP value

    

0.146

 Number of patients

767

226

421

120

 

 Mean ± SD, mg/L

16.7 ± 26.0

15.8 ± 28.2

18.2 ± 25.3

13.2 ± 23.5

 

Most recent CRP level

    

<0.001

 Not elevated (<3.5 mg/L), n (%)

219 (23.96 %)

72 (27.07 %)

96 (19.55 %)

51 (32.48 %)

 

 Elevated (≥3.5 mg/L), n (%)

548 (59.96 %)

154 (57.89 %)

325 (66.19 %)

69 (43.95 %)

 

 Results not available, n (%)

147 (16.08 %)

40 (15.04 %)

70 (14.26 %)

37 (23.57 %)

 

Most recent CRP level (excluding missing)

    

<0.001

 Not elevated (<3.5 mg/L), n (%)

219 (28.55 %)

72 (31.86 %)

96 (22.80 %)

51 (42.50 %)

 

 Elevated (≥3.5 mg/L), n (%)

548 (71.45 %)

154 (68.14 %)

325 (77.20 %)

69 (57.50 %)

 

Most recent ESR value

    

0.009

 Number of patients

846

252

464

130

 

 Mean ± SD, mm/h

29.0 ± 23.6

26.8 ± 23.9

31.2 ± 23.6

25.3 ± 22.8

 

Most recent ESR level

    

<0.001

 Not elevated (<28 mm/h), n (%)

482 (52.74 %)

158 (59.40 %)

237 (48.27 %)

87 (55.41 %)

 

 Elevated (≥28 mm/h), n (%)

364 (39.82 %)

94 (35.34 %)

227 (46.23 %)

43 (27.39 %)

 

 Results not available, n (%)

68 (7.44 %)

14 (5.26 %)

27 (5.50 %)

27 (17.20 %)

 

Most recent ESR level (excluding missing)

    

<0.001

 Not elevated (<28 mm/h), n (%)

482 (56.97 %)

158 (62.70 %)

237 (51.08 %)

87 (66.92 %)

 

 Elevated (≥28 mm/h), n (%)

364 (43.03 %)

94 (37.30 %)

227 (48.92 %)

43 (33.08 %)

 
  1. Abbreviations: AS ankylosing spondylitis, CRP C-reactive protein, ESR erythrocyte sedimentation rate, HLA-B27 human leukocyte antigen B27, IBP inflammatory back pain, nr-axSpA nonradiographic axial spondyloarthritis, NSAID nonsteroidal anti-inflammatory drug, SpA spondyloarthritis
  2. The p values represent the omnibus statistical comparison of percentages (or means) across IBP groups based on the chi-square values