Factors associated with continuation of the switched TNFi
| Baseline characteristics* | Patients continuing the switched TNFi | ||||
| Yes (n=39) | No (n=85) | Univariate HR (95% CI) | Multivariate HR (95% CI) | P value | |
| Age (years) (≥45 years old) | 6 (15.4) | 13 (15.3) | 1.1 (0.6 to 1.9) | _ | _ |
| Sex (male) | 14 (35.9) | 26 (30.6) | 1.3 (0.8 to 1.9) | _ | |
| Initiation of treatment ≤18 months | 6 (15.4) | 48 (56.5) | 0.7 (0.5 to 1.1) | 0.99 (0.6 to 1.6) | 0.95 |
| Employment (blue collar) | 10/38 (26.3) | 13 (15.3) | 1.4 (0.8 to 2.6) | _ | _ |
| Education (university) | 20 (51.3) | 41 (48.2) | 1.3 (0.8 to 2.0) | _ | _ |
| HLA-B27 positive | 23 (59.0) | 38 (44.7) | 1.6 (1.1 to 2.5) | 1.8 (1.1 to 2.8) | 0.01 |
| MRI sacroiliitis positive | 17 (43.6) | 22/83 (26.5) | 1.3 (0.8 to 2.0) | _ | _ |
| Radiographic sacroiliitis positive | 6 (15.4) | 11 (12.9) | 1.1 (0.6 to 2.1) | _ | _ |
| History of good NSAID response | 32 (82.1) | 70/84 (83.3) | 0.9 (0.5 to 1.6) | _ | _ |
| NSAID score week | 50.6 (46.1) | 65.1 (55.7) | 1.1 (1.0 to 1.1) | 1.1 (1.0 to 1.1) | 0.06 |
| History of arthritis | 9/38 (23.7) | 26/84 (31.0) | 1.2 (0.7 to 1.9) | _ | _ |
| History of dactylitis | 1 (2.6) | 13/84 (15.5) | 0.7 (0.4 to 1.3) | _ | _ |
| History of enthesitis | 29 (74.4) | 63 (74.1) | 1.0 (0.6 to 1.6) | _ | _ |
| CRP (≥6 mg/L) | 14 (35.9) | 24/83 (28.9) | 1.2 (0.7 to 1.9) | _ | _ |
| ASDAS-CRP (per point) | 3.1 (0.7) | 3.3 (0.9) | 0.9 (0.7 to 1.2) | _ | _ |
| BASDAI (range 0–10) | 5.6 (1.6) | 6.0 (1.4) | 0.9 (0.8 to 1.1) | _ | _ |
| Presence of at least one objective sign of inflammation or structural damage | 18/37 (48.6) | 27/83 (32.5) | 1.2 (0.7 to 1.9) | _ | _ |
| BASFI (range 0–10) | 4.2 (2.2) | 4.8 (2.1) | 1.0 (0.9 to 1.1) | _ | _ |
| Centre in which TNFi inclusion rate was over 20% over follow-up | 32 (82.1) | 67 (78.8) | 1.0 (0.6 to 1.7) | _ | _ |
| Centre in which TNFi prescription rate was over 30% over follow-up | 23 (59.0) | 72 (84.7) | 0.5 (0.3 to 0.9) | 0.4 (0.2 to 0.8) | 0.01 |
*Values are presented as mean (SD) and n (%) for continuous and categorical variables, respectively.
ASDAS-CRP, Ankylosing Spondylitis Disease Activity Score using CRP; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; CRP, C reactive protein; NSAID, non-steroidal anti-inflammatory drugs; TNFi, tumour necrosis factor inhibitor.