Multivariate Poisson regression analysis per age group
| Group <40 | RR (95% CI) |
|---|---|
| Baseline JSN | 1.07 (0.95 to 1.22) |
| Swollen joint count | 1.09 (1.01 to 1.18) |
| RF−/ACPA− | Ref |
| RF+/ACPA− | 1.80 (0.29 to 11.25) |
| RF−/ACPA+ | 3.14 (0.34 to 28.66) |
| RF+/ACPA+ | 4.00 (0.88 to 18.08) |
| Time average ESR | 1.04 (1.02 to 1.06) |
| Group ≥40<55 | |
| Baseline JSN | 1.02 (0.95 to 1.10) |
| Baseline Erosions | 1.04 (0.98 to 1.10) |
| Ritchie Articular Index | 0.96 (0.89 to 1.03) |
| Swollen joint count | 1.00 (0.95 to 1.10) |
| RF−/ACPA− | Ref |
| RF+/ACPA− | 2.67 (0.76 to 9.39) |
| RF−/ACPA+ | 1.28 (0.37 to 4.43) |
| RF+/ACPA+ | 2.65 (0.95 to 7.38) |
| Time average ESR | 1.01 (0.99 to 1.04) |
| Group ≥55 | |
| Smoking at baseline | 1.46 (0.81 to 2.63) |
| RF−/ACPA− | Ref |
| RF+/ACPA− | 1.33 (0.45 to 3.98) |
| RF−ACPA+ | 2.31 (0.75 to 7.10) |
| RF+/ACPA+ | 3.27 (1.25 to 8.53) |
| Time average ESR | 1.02 (1.00 to 1.03) |
Bold typeface represents risk factors that attained significance. 95% CI, 95% CI after Bonferroni correction; ACPA, anticitrullinated protein antibodies; Erosions, erosion score (SHS); ESR, erythrocyte sedimentation rate; JSN, joint space narrowing; RF, rheumatoid factor; RR, relative risk; SHS, Sharp/van der Heijde score.