Univariate Poisson regression analysis per age group
| Group <40 | Group ≥40<55 | Group ≥55 | |
|---|---|---|---|
| RR (95% CI) | RR (95% CI) | RR (95% CI) | |
| Baseline smoking | 0.83 (0.16 to 4.23) | 1.18 (0.60 to 2.32) | 2.00 (1.11 to 3.58) |
| BMI<25 | Ref | Ref | Ref |
| BMI>25<30 | 0.91 (0.22 to 3.82) | 0.58 (0.37 to 1.50) | 1.12 (0.58 to 2.14) |
| BMI>30 | 0.28 (0.05 to 1.66) | 0.74 (0.19 to 1.73) | 1.19 (0.50 to 2.87) |
| Ritchie Articular Index | 1.00 (0.94 to 1.06) | 0.95 (0.89 to 1.01) | 0.98 (0.93 to 1.03) |
| Swollen joint count | 1.11 (1.02 to 1.21) | 0.97 (0.93 to 1.01) | 1.01 (0.98 to 1.05) |
| JSN | 1.17 (1.01 to 1.35) | 1.06 (0.99 to 1.14) | 1.00 (0.94 to 1.07) |
| Erosions | 1.13 (0.90 to 1.41) | 1.06 (1.01 to 1.12) | 1.02 (0.89 to 1.15) |
| RF−/ACPA− | Ref | Ref | Ref |
| RF+/ACPA− | 1.65 (0.28 to 9.82) | 3.31 (0.93 to 11.75) | 1.47 (0.48 to 4.47) |
| RF−/ACPA+ | 2.78 (0.48 to 16.15) | 1.76 (0.54 to 5.79) | 2.52 (0.84 to 7.54) |
| RF+/ACPA+ | 5.39 (1.25 to 23.15) | 3.41 (1.33 to 8.71) | 4.19 (1.58 to 11.07) |
| RF− | Ref | Ref | Ref |
| RF+ | 2.81 (0.90 to 8.77) | 2.88 (1.40 to 5.96) | 2.63 (1.31 to 5.28) |
| ACPA− | Ref | Ref | Ref |
| ACPA+ | 3.79 (1.21 to 11.89) | 2.02 (0.94 to 4.33) | 3.39 (1.58 to 7.28) |
| Average ESR over time | 1.04 (1.00 to 1.08) | 1.02 (1.00 to 1.04) | 1.02 (1.01 to 1.03) |
| Sequential monotherapy | Ref | Ref | Ref |
| Step up to combination therapy | 0.44 (0.07 to 2.79) | 1.29 (0.56 to 3.02) | 0.81 (0.34 to 1.93) |
| Initial combination therapy with prednisone | 0.89 (0.20 to 3.93) | 0.77 (0.36 to 1.64) | 0.93 (0.38 to 2.25) |
| Initial combination therapy with infliximab | 0.20 (0.04 to 0.95) | 0.49 (0.19 to 1.27) | 0.84 (0.36 to 2.00) |
Bold typeface represents risk factors that attained significance. 95% CI, 98.33% (Bonferroni correction) CI; ACPA, anticitrullinated protein antibodies; BMI, body mass index; Erosions, erosion score (SHS); ESR, erythrocyte sedimentation rate; JSN, joint space narrowing; RF, rheumatoid factor; RR, relative risk; SHS, Sharp/van der Heijde score.