Baseline characteristics of axSpA smokers and non-smokers with complete covariate information starting a first TNFi differentiated by baseline CRP status
| Elevated baseline CRP (N=281) | Normal baseline CRP (N=209) | |||||
|---|---|---|---|---|---|---|
| Non-smokers N=93 | Ever smokers N=188 | p Value | Non-smokers N=81 | Ever smokers N=128 | p Value | |
| Male sex, % | 67.7 | 73.4 | 0.40 | 50.6 | 64.1 | 0.09 |
| Age, years | 41.6 (12.5) | 45.2 (11.2) | 0.02 | 42.2 (12.2) | 41.9 (11.5) | 0.89 |
| Symptom duration, years, median (IQR) | 9.0 (3.3; 16.5) | 10.8 (5.8; 20.7) | 0.08 | 10.1 (4.8; 18.4) | 8.1 (3.1; 17.9) | 0.48 |
| HLA-B27 positive, % | 86.0 | 84.6 | 0.89 | 70.4 | 77.3 | 0.33 |
| Ankylosing spondylitis, % | 80.7 | 88.3 | 0.12 | 67.9 | 72.7 | 0.56 |
| BASDAI | 5.8 (2.0) | 5.4 (1.9) | 0.17 | 5.0 (2.1) | 5.7 (1.9) | 0.07 |
| ASDAS-CRP | 4.0 (0.9) | 3.8 (0.8) | 0.15 | 2.8 (0.9) | 3.0 (0.7) | 0.16 |
| CRP (mg/L), median (IQR) | 16.0 (11.0; 37.2) | 17.0 (10.0; 33.0) | 0.60 | 5.0 (2.0; 8.0) | 3.0 (1.0; 7.0) | 0.32 |
| ESR (mm/h), median (IQR) | 26.0 (12.5; 41.0) | 24.0 (15.0; 40.0) | 0.81 | 8.0 (4.0; 14.0) | 6.0 (3.2; 14.0) | 0.75 |
| Physician GA | 5.1 (2.0) | 5.0 (2.0) | 0.77 | 4.1 (2.2) | 4.0 (1.8) | 0.73 |
| Patient GA | 6.6 (2.2) | 6.5 (2.4) | 0.68 | 5.8 (2.6) | 6.5 (2.2) | 0.03 |
| BASFI | 4.1 (2.5) | 4.6 (2.3) | 0.11 | 3.1 (2.1) | 4.3 (2.3) | <0.001 |
| BASMI, median (IQR) | 2.0 (1.0; 4.0) | 3.0 (1.0; 4.5) | 0.10 | 1.0 (0.0; 2.0) | 1.0 (0.0; 3.0) | 0.05 |
| EQ-5D | 57.1 (23.2) | 55.3 (21.7) | 0.53 | 62.8 (19.3) | 50.3 (22.0) | <0.001 |
| SF-12 PCS | 36.6 (9.9) | 35.2 (9.0) | 0.28 | 37.8 (8.8) | 36.2 (9.3) | 0.22 |
| SF-12 MCS | 44.3 (11.2) | 44.3 (11.6) | 0.98 | 43.3 (11.1) | 40.0 (10.8) | 0.05 |
| Peripheral arthritis ever, % | 60.2 | 39.1 | 0.001 | 46.8 | 44.1 | 0.81 |
| On NSAID, % | 85.0 | 75.0 | 0.08 | 75.3 | 80.5 | 0.48 |
| On DMARD, % | 25.8 | 16.0 | 0.07 | 23.5 | 12.5 | 0.06 |
| BMI | 25.0 (4.5) | 26.0 (4.8) | 0.09 | 25.2 (4.9) | 24.8 (4.3) | 0.61 |
| Education, years | 14.5 (3.2) | 13.8 (3.1) | 0.08 | 14.2 (3.1) | 13.2 (2.9) | 0.02 |
| Exercise sessions/week | ||||||
| 0 sessions, % | 26.9 | 35.1 | 0.35 | 25.9 | 30.5 | 0.44 |
| 1–2 sessions, % | 44.1 | 41.0 | 43.2 | 34.4 | ||
| ≥3 sessions, % | 29.0 | 23.9 | 30.9 | 35.2 | ||
Except where indicated otherwise, values are the mean (SD).
ASDAS-CRP, Ankylosing Spondylitis Disease Activity Score using the CRP; axSpA, axial spondyloarthritis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; BMI, body mass index; CRP, C-reactive protein; DMARD, disease modifying antirheumatic drug; EQ-5D, EuroQol 5-domain; ESR, erythrocyte sedimentation rate; GA, global assessment; HLA, human leucocyte antigen; MCS, mental component summary; NSAID, non-steroidal anti-inflammatory drug; PCS, physical component summary; peripheral, peripheral; SF-12, short form 12; TNFi, tumour necrosis factor inhibitor.