Table 1

Comparison of baseline characteristics between HLA-B27 positive and negative patients

HLA-B27 positiveHLA-B27 negativep Value
Male gender206 (51.2%)92 (37.4%)0.001
Mean age (years)32.5±8.435.6±8.7<0.001
Mean age at onset of IBP (years)31.0±8.534.0±8.8<0.001
Mean duration of axial symptoms (years)1.5±1.01.5±0.80.64
Mean delay in diagnosis (years)2.7±4.23.7±5.10.01
Caucasian race368 (91.5%)212 (86.5%)0.04
Family history of ankylosing spondylitis120 (30.2%)48 (19.7%)0.003
Presence of peripheral arthritis216 (53.9%)165 (67.3%)0.001
Mean age at onset of peripheral arthritis (years)31.5±9.632.8±8.70.02
Presence of enthesitis186 (46.3%)158 (64.2%)<0.001
Using NSAIDs299 (74.4%)147 (59.8%)<0.001
Ever used NSAIDs386 (96.0%)217 (88.2%)<0.001
Using steroids54 (13.4%)29 (11.8%)0.54
Using DMARDs36 (9.0%)23 (9.3%)0.87
Ever used DMARDs54 (13.5%)36 (14.6%)0.68
Using analgesics249 (61.9%)164 (66.7%)0.23
Mean CRP (mg/l)8.1±14.07.6±14.00.67
 Percentage of patients with elevated CRP28.630.60.59
Mean ESR (mm/h)14.5±16.314.0±16.00.72
 Percentage of patients with elevated ESR22.017.60.19
Percentage of patients with elevated CRP or ESR34.137.40.40
Dactylitis54 (13.4%)38 (15.4%)0.48
Presence of any extra-articular features98 (24.4%)82 (33.3%)0.01
Psoriasis57 (14.2%)52 (21.1%)0.02
Crohn's disease7 (1.7%)11 (4.5%)0.04
Ulcerative colitis5 (1.2%)9 (3.7%)0.04
Palmoplantar pustulosis5 (1.2%)3 (1.2%)0.98
History of uveitis38 (9.5%)18 (7.3%)0.35
BASDAI4.2±2.14.9±1.8<0.001
BASDAI ≥4213 (53.4%)178 (73.3%)<0.001
ASDAS-CRP2.4±1.12.7±1.00.07
ASDAS-CRP >2.1233 (60.5%)159 (68.2%)0.053
ASDAS-ESR2.4±1.02.7±0.90.04
ASDAS-ESR >2.1226 (59.0%)159 (70.4%)0.01
BASFI2.8±2.23.5±2.3<0.001
BASFI ≥4120 (30.2%)99 (41.4%)0.004
Intensity of axial pain (NRS)4.6±2.85.5±2.5<0.001
Intensity of nocturnal axial pain (NRS)4.3±3.15.1±2.8<0.001
Intensity of peripheral joints pain (NRS)3.0±2.83.8±2.7<0.001
Physician global assessment4.2±2.24.6±2.10.01
Tender joint count (53 joint count)3.4±6.66.2±10.8<0.001
Swollen joint count (28 joint count)0.1±0.7 8.50.2±1.0 7.30.28
 Percentage of patients with swollen joint(s)8.57.30.55
Number of missing work days due to spondyloarthritis26.6±55.346.7±87.90.003
BASMI2.2±0.92.4±0.90.03
Chest expansion (cm)5.7±2.05.5±2.30.33
MRI inflammatory lesions of the SIJ168 (44.1%)57 (24.9%)<0.001
MRI inflammatory lesions of the spine98 (25.9%)38 (16.8%)0.01
MRI structural lesions of the SIJ119 (31.2%)49 (21.4%)0.01
MRI structural lesions of the spine38 (10.1%)16 (7.2%)0.23
Definite radiographic changes in SIJ131 (32.8%)49 (19.4%)0.001
mSASSS1.2±3.00.9±2.90.34
mSASSS >0105 (26.9%)51 (22.1%)0.18
  • ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; CRP, C reactive protein; DMARDs, disease-modifying antirheumatic drugs; ESR, erythrocyte sedimentation rate; HLA-B27, human leucocyte antigen B27; IBP, inflammatory back pain; mSASSS, modified Stoke Ankylosing Spondylitis Spine Score; NSAIDs, non-steroidal anti-inflammatory drugs; NRS, Numerical Rating Scale; SIJ, sacroiliac joints.