Table 2.
Demographic and clinical characteristics of IFNα-positive and IFNα-negative patients
| N = 346 | IFNα-negative (n = 255) | IFNα-positivea (n = 91) | p-value |
|---|---|---|---|
| Age, yearsb | 58 (18–81) | 58 (21–82) | 0.53 |
| Female sexc | 170 (67%) | 64 (70%) | 0.60 |
| BMI, kg/m2b | 25 (18–43) | 26 (19–43) | 0.22 |
| Current smokerc | 46 (18%) | 25 (27%) | 0.07 |
| Autoantibody statusc | < 0.0001 | ||
| RF-ACPA- | 33 (13%) | 3 (3%) | p < 0.05d |
| RF+ACPA- | 23 (9%) | 2 (2%) | ns |
| RF-ACPA+ | 52 (20%) | 2 (2%) | p < 0.05d |
| RF+ACPA+ | 146 (57%) | 84 (92%) | p < 0.05d |
| Disease activity day 1b | |||
| CDAI | 27.8 (7.8–68.7) | 28.6 (10.1–68.4) | 0.13 |
| DAS28-CRP | 5.1 (2.2–8.3) | 5.1 (3.3–7.7) | 0.38 |
| DAS28-ESR | 5.5 (2.6–8.7) | 5.5 (3.3–8.2) | 0.43 |
| SJC-66 | 11 (1–42) | 11 (2–38) | 0.68 |
| TJC-68 | 13 (0–49) | 16 (2–62) | 0.16 |
| CRP, mg/L | 14 (0.3–216) | 8 (0.5–190) | 0.16 |
| ESR, mm/h | 28 (2–115) | 28 (4–108) | 0.26 |
| PGA, mm | 59 (2–100) | 56 (22–100) | 0.59 |
| Disease activity week 24b | |||
| CDAI | 3.4 (0–28.3) | 3.5 (0–26.6) | 0.47 |
| DAS28-CRP | 2.0 (1.1–4.8) | 2.0 (1.0–5.0) | 0.82 |
| DAS28-ESR | 2.3 (0–6.0) | 2.2 (0–5.8) | 0.91 |
| SJC-66 | 0 (0–9) | 0 (0–7) | 0.88 |
| TJC-68 | 1 (0–37) | 2 (0–41) | 0.22 |
| CRP, mg/L | 1 (0–39) | 1 (0.1–15) | 0.86 |
| ESR, mm/h | 8 (1–78) | 8 (1–48) | 0.52 |
| PGA, mm | 11 (0–78) | 14 (0–92) | 0.40 |
BMI body mass index, RF rheumatoid factor, ACPA anti-citrullinated protein antibodies, CDAI clinical disease activity index, DAS28 disease activity score 28 joints, SJC-66 swollen joint count, 66 joints, TJC-68 tender joint count, 68 joints, CRP C-reactive protein, ESR erythrocyte sedimentation rate, PGA patient global assessment
aIFNα positivity defined as IFNα protein level above 136 fg/mL
bMedian (range), Mann-Whitney U-test
cn (%), Fisher’s exact test
dp < 0.05 after post hoc step-down Bonferroni-Holm correction for multiple testing