Sensitivity analyses: estimates for csDMARD comedication from multivariable Cox regression models
| AS | uSpA | Pooled group AS and uSpA | ||||
|---|---|---|---|---|---|---|
| HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value | |
| Main analyses (see table 3 for full models AS and uSpA) | 0.71 (0.59 to 0.85) | <0.001 | 0.82 (0.69 to 0.97) | 0.020 | ||
| Time-varying csDMARD covariate | 0.61 (0.51 to 0.74) | <0.001 | 0.81 (0.69 to 0.96) | 0.017 | ||
| Alternative csDMARD categories | 0.001 | 0.034 | ||||
| MTX vs none | 0.74 (0.61 to 0.91) | 0.004 | 0.79 (0.66 to 0.94) | 0.010 | ||
| Other vs none | 0.59 (0.41 to 0.83) | 0.002 | 0.94 (0.71 to 1.26) | 0.691 | ||
| Exclusion of patients with swollen joints at baseline* | 0.76 (0.66 to 0.89) | <0.001 | ||||
| csDMARD groups† | <0.001 | 0.017 | ||||
| csDMARD starters vs non-users | 0.72 (0.52 to 1.01) | 0.058 | 0.71 (0.49 to 1.01) | 0.058 | ||
| csDMARD continued users vs non-users | 0.50 (0.38 to 0.64) | <0.001 | 0.75 (0.59 to 0.95) | 0.018 | ||
| csDMARD stoppers vs non-users | 0.65 (0.48 to 0.89) | 0.006 | 1.05 (0.80 to 1.39) | 0.716 | ||
| csDMARD groups‡ | <0.001 | |||||
| csDMARD starters vs non-users | 0.65 (0.50 to 0.85) | 0.002 | ||||
| csDMARD continued users vs non-users | 0.62 (0.51 to 0.76) | <0.001 | ||||
| csDMARD stoppers vs non-users | 0.79 (0.63 to 1.00) | 0.049 | ||||
The additional covariates in the models were as follows: age, sex, TNFi type, start year, hospital days, outpatient visits, disposable income, education.
*N=1839 (AS N=1105, 81.0% of total, 398 patients with and 707 patients without csDMARD comedication; uSpA N=734, 63.5% of total, 311 patients with and 423 patients without csDMARD comedication).
†Patients starting TNFi after 1 January 2006: AS N=1049 (csDMARD ‘starters’ n=108, ‘continued users’ n=288, ‘stoppers’ n=148, ‘non-users’ n=505); uSpA N=853 (csDMARD ‘starters’ n=90, ‘continued users’ n=325, ‘stoppers’ n=152, ‘non-users’ n=286). Information on csDMARD use for these analyses was retrieved from the Prescribed Drugs Register.
‡Patients starting TNFi after 1 January 2006, excluding patients with swollen joints at baseline: N=1448 (csDMARD ‘starters’ n=168, ‘continued users’ n=390, ‘stoppers’ n=224, ‘non-users’ n=666). Information on csDMARD use for this analysis was retrieved from the Prescribed Drugs Register.
AS, ankylosing spondylitis; csDMARD, conventional synthetic disease modifying antirheumatic drug; MTX, methotrexate; uSpA, undifferentiated spondyloarthritis.