Baseline characteristics in smokers and non-smokers with axSpA starting a first TNFi
| N | Non-smokers N=263 | Ever smokers N=435 | p Value | Past smokers N=167 | Current smokers N=268 | p Value | |
|---|---|---|---|---|---|---|---|
| Male sex, % | 698 | 52.9 | 66.9 | <0.001 | 62.9 | 69.4 | 0.19 |
| Age, years | 698 | 42.0 (12.5) | 43.7 (11.5) | 0.06 | 47.6 (11.7) | 41.3 (10.6) | <0.001 |
| Symptom duration, years, median (IQR) | 689 | 10.1 (3.4; 18.3) | 9.8 (4.1; 17.9) | 0.67 | 11.5 (5.3; 18.4) | 8.9 (3.6; 16.8) | 0.06 |
| HLA-B27 positive, % | 623 | 77.8 | 81.7 | 0.29 | 77.9 | 84.1 | 0.16 |
| AS, % | 605 | 76.0 | 82.5 | 0.07 | 80.8 | 83.5 | 0.60 |
| BASDAI | 624 | 5.5 (2.0) | 5.5 (1.9) | 0.83 | 5.4 (2.0) | 5.5 (1.9) | 0.56 |
| ASDAS-CRP | 611 | 3.4 (1.0) | 3.5 (0.9) | 0.14 | 3.5 (1.0) | 3.5 (0.8) | 0.41 |
| CRP (mg/L), median (IQR) | 652 | 8.0 (4.0; 17.0) | 9.0 (5.0; 22.0) | 0.17 | 9.0 (5.0; 21.5) | 9.0 (5.0; 22.0) | 0.94 |
| Elevated CRP, % | 665 | 49.0 | 40.6 | 0.04 | 41.8 | 39.9 | 0.79 |
| ESR (mm/h), median (IQR) | 653 | 13.0 (6.0–28.0) | 16.0 (7.0–32.0) | 0.16 | 19.5 (6.2; 33.8) | 16.0 (7.0; 32.0) | 0.34 |
| Physician GA | 659 | 4.6 (2.1) | 4.8 (1.9) | 0.38 | 4.6 (2.0) | 5.0 (1.9) | 0.26 |
| Patient GA | 654 | 6.2 (2.4) | 6.5 (2.3) | 0.17 | 6.4 (2.4) | 6.6 (2.3) | 0.37 |
| BASFI | 656 | 3.6 (2.3) | 4.4 (2.4) | <0.001 | 4.2 (2.3) | 4.6 (2.5) | 0.11 |
| BASMI, median (IQR) | 606 | 2.0 (1.0–3.0) | 2.0 (1.0–4.0) | 0.02 | 2.0 (1.0; 3.0) | 2.0 (1.0; 4.2) | 0.56 |
| EQ-5D | 645 | 58.7 (21.2) | 53.2 (21.4) | 0.002 | 55.0 (21.2) | 52.1 (21.5) | 0.18 |
| SF-12 PCS | 588 | 36.9 (9.6) | 35.2 (9.1) | 0.04 | 35.1 (9.3) | 35.3 (9.0) | 0.80 |
| SF-12 MCS | 588 | 43.9 (11.0) | 42.6 (11.2) | 0.18 | 44.7 (10.9) | 41.4 (11.3) | 0.01 |
| Peripheral arthritis ever, % | 681 | 51.0 | 39.9 | 0.006 | 41.0 | 39.2 | 0.80 |
| NSAID use, % | 698 | 74.5 | 77.5 | 0.43 | 74.8 | 79.1 | 0.36 |
| DMARD use, % | 698 | 21.7 | 14.2 | 0.02 | 17.4 | 12.3 | 0.19 |
| BMI | 685 | 25.0 (4.7) | 25.5 (4.8) | 0.18 | 26.2 (5.2) | 25.1 (4.4) | 0.02 |
| Education, years | 691 | 14.4 (3.1) | 13.5 (3.0) | <0.001 | 13.4 (3.1) | 13.6 (2.9) | 0.52 |
| Exercise sessions/week | |||||||
| 0 sessions, % | 201 | 25.8 | 31.8 | 0.11 | 25.8 | 35.5 | 0.10 |
| 1–2 sessions, % | 268 | 43.0 | 37.2 | 39.3 | 35.9 | ||
| ≥3 sessions, % | 212 | 31.2 | 31.1 | 35.0 | 28.6 | ||
Except where indicated otherwise, values are the mean (SD).
AS, ankylosing spondylitis; ASDAS-CRP, Ankylosing Spondylitis Disease Activity Score using the C-reactive protein (CRP) level; 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; 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; SF-12, short form 12; TNFi, tumour necrosis factor inhibitor.