Table 4.
Multiple adjusted Cox proportional hazards model for analysis of drug discontinuation of a first TNF inhibitor in early versus established axSpA
| Population | Variable | Unadjusted analysis | Adjusted model 1 | Adjusted model 2 | Adjusted model 3 | ||||||||
| HR | 95% CI | P value | HR | 95% CI | P value | HR | 95% CI | P value | HR | 95% CI | P value | ||
| Main analysis: all patients diagnosed as having axSpA |
Early vs established disease | 1.22 | 1.03; 1.44 | 0.02 | 1.07 | 0.87; 1.31 | 0.51 | 1.00 | 0.79; 1.28 | 0.98 | 1.01 | 0.79; 1.29 | 0.91 |
| Age | 1.00 | 0.99; 1.00 | 0.46 | 1.00 | 0.99; 1.00 | 0.41 | 0.99 | 0.98; 1.00 | 0.06 | ||||
| Female sex | 1.56 | 1.31; 1.85 | <0.001 | 1.51 | 1.24; 1.85 | <0.001 | 1.51 | 1.22; 1.85 | <0.001 | ||||
| HLA-B27 negativity | 1.39 | 1.16; 1.67 | <0.001 | 1.40 | 1.13; 1.73 | 0.002 | 1.25 | 1.01; 1.54 | 0.04 | ||||
| Education vocational | 0.83 | 0.66; 1.04 | 0.11 | 0.77 | 0.58; 1.01 | 0.06 | 0.83 | 0.64; 1.08 | 0.17 | ||||
| Education academic | 0.77 | 0.60; 1.00 | 0.048 | 0.82 | 0.61; 1.12 | 0.21 | 0.97 | 0.72; 1.30 | 0.81 | ||||
| ASDAS | 0.82 | 0.74; 0.92 | <0.001 | ||||||||||
| Body mass index | 1.03 | 1.00; 1.05 | 0.03 | ||||||||||
| Current smoking | 1.11 | 0.91; 1.37 | 0.30 | ||||||||||
| Elevated CRP | 0.58 | 0.47; 0.71 | <0.001 | ||||||||||
| Sacroiliitis on MRI | 0.85 | 0.70; 1.03 | 0.10 | ||||||||||
| (Number of patients/events) | (1124/735) | (843/573) | (614/424) | (619/436) | |||||||||
| Sensitivity analysis: patients fulfilling the ASAS classification criteria |
Early vs established disease | 1.31 | 1.06; 1.61 | 0.01 | 1.23 | 0.95; 1.59 | 0.12 | 1.12 | 0.83; 1.52 | 0.44 | 1.05 | 0.78; 1.42 | 0.73 |
| Age | 1.00 | 0.99; 1.01 | 0.61 | 1.00 | 0.99; 1.01 | 0.41 | 0.99 | 0.98; 1.00 | 0.04 | ||||
| Female sex | 1.53 | 1.25; 1.87 | <0.001 | 1.49 | 1.18; 1.87 | <0.001 | 1.45 | 1.15; 1.83 | 0.002 | ||||
| HLA-B27 negativity | 1.40 | 1.12; 1.75 | 0.004 | 1.33 | 1.03; 1.72 | 0.03 | 1.23 | 0.94; 1.60 | 0.13 | ||||
| Education vocational | 0.85 | 0.64; 1.11 | 0.23 | 0.76 | 0.55; 1.05 | 0.10 | 0.79 | 0.58; 1.08 | 0.14 | ||||
| Education academic | 0.93 | 0.69; 1.25 | 0.62 | 0.91 | 0.64; 1.30 | 0.61 | 1.02 | 0.72; 1.43 | 0.93 | ||||
| ASDAS | 0.82 | 0.73; 0.93 | 0.002 | ||||||||||
| Body mass index | 1.02 | 0.99; 1.05 | 0.12 | ||||||||||
| Current smoking | 1.06 | 0.84; 1.33 | 0.62 | ||||||||||
| Elevated CRP | 0.54 | 0.43; 0.68 | <0.001 | ||||||||||
| Sacroiliitis on MRI | 0.89 | 0.71; 1.12 | 0.33 | ||||||||||
| (Number of patients/events) | (816/526) | (623/419) | (482/328) | (488/340) | |||||||||
Statistically significant results are shown in bold. The number of patients assessed and the number of treatment discontinuations are indicated for each statistical model at the bottom.
ASAS, Assessment of SpondyloArthritis international Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; axSpA, axial spondyloarthritis; CRP, C reactive protein; HLA-B27, human leucocyte antigen-B27; TNF, tumour necrosis factor.