Univariate HRs and results of multiple Cox regression
| Univariate | Multiple Cox regression 1 | Multiple Cox regression 2 | ||||
|---|---|---|---|---|---|---|
| HR | 95% CI | HR | 95% CI | HR | 95% CI | |
| Age at event (by 5 years) | 1.48 | (1.25 to 1.75) | 1.55 | (1.30 to 1.84) | 1.57 | (1.32 to 1.87) |
| Male | 1.68 | (0.84 to 3.34) | 1.58 | (0.79 to 3.20) | 1.45 | (0.72 to 2.90) |
| BMI | 1.00 | (0.94 to 1.06) | ||||
| bDMARD failures (reference: 0) | ||||||
| 1 bDMARD | 1.54 | (0.67 to 3.52) | ||||
| ≥2 bDMARDs | 0.71 | (0.17 to 3.00) | ||||
| DAS28 (current) | 1.14 | (0.92 to 1.42) | ||||
| DAS28 (average last 12 months) | 1.16 | (0.91 to 1.48) | ||||
| DMARD (reference: csDMARDs) | ||||||
| TNFi | 0.84 | (0.39 to 1.80) | 1.00 | (0.46 to 2.20) | 1.04 | (0.48 to 2.26) |
| Other bDMARDs | 0.40 | (0.09 to 1.78) | 0.41 | (0.09 to 1.84) | 0.33 | (0.08 to 1.44) |
| Tocilizumab | 4.17 | (1.87 to 9.27) | 5.11 | (2.31 to 11.3) | 4.48 | (2.01 to 9.99) |
| GCs | ||||||
| Current GC (by 5 mg) | 1.22 | (1.13 to 1.31) | 1.28 | (1.18 to 1.38) | ||
| Cumulative GCs* | 1.81 | (1.47 to 2.22) | 1.87 | (1.50 to 2.33) | ||
| NSAIDs | ||||||
| Current NSAID | 1.80 | (0.92 to 3.53) | 2.18 | (1.11 to 4.31) | ||
| Cumulative NSAIDs† | 2.71 | (1.20 to 6.12) | 3.00 | (1.33 to 6.82) | ||
In Cox regression 1, we adjusted for current doses of GCs and NSAIDs, whereas in Cox regression 2 for cumulative doses.
*Concomitant GC use (range: 0 to 1) was calculated for each patient as the area under curve of follow-up month with medium doses (>5 to 10 mg/day, weight of 0.5) plus follow-up month with high doses (>10 mg/day, weight of 1) and then divided by total no. of follow-up months.
†Cumulative treatment with NSAIDs (range: 0 to 1) was calculated for each patient as: no. of follow-ups with concomitant NSAIDs use divided by the total no. of follow-ups.
bDMARD, biologic disease-modifying anti-rheumatic drug; BMI, body mass index; csDMARDs, conventional synthetic disease-modifying anti-rheumatic drugs; DAS28, disease activity score based on 28 joints; GC, glucocorticoid; NSAIDs, non-steroidal anti-inflammatory drugs; other bDMARDs, abatacept and rituximab; TNFi, tumour necrosis factor-α inhibitor.