Table 1. Patient Characteristics According to PAD3/4 Cross-Reactive Antibody Status.
| Characteristic | Total (n = 176) | No anti-PAD (n = 120) | Anti-PAD4 only (n = 37) | Anti-PAD3/4XR (n = 19) | p-value* |
| Age, years | 59±9 | 59±8 | 58±9 | 62±7 | 0.093 |
| Male, n (%) | 71 (40) | 43 (36) | 21 (57) | 8 (42) | 0.60 |
| White, n (%) | 152 (86) | 101 (84) | 35 (95) | 16 (84) | 0.99 |
| Any college, n (%) | 133 (76) | 86 (72) | 31 (84) | 16 (84) | 0.25 |
| Ever smoking, n (%) | 105 (60) | 80 (67) | 16 (43) | 10 (53) | 0.23 |
| Current smoking, n (%) | 20 (11) | 19 (16) | 2 (5) | 0 (0) | 0.075 |
| Reported lung disease (n = 168), n (%) | 27 (16) | 22 (19) | 4 (12) | 1 (6) | 0.30 |
| RA duration, years | 8 (4–17) | 7 (4–12) | 15 (7–23) | 20 (11–28) | <0.001 |
| RF or CCP2 seropositivity, n (%) | 137 (78) | 87 (73) | 33 (89) | 18 (95) | 0.043 |
| RF seropositivity, n (%) | 114 (65) | 73 (61) | 26 (70) | 15 (79) | 0.20 |
| CCP2 seropositivity, n (%) | 122 (70) | 76 (64) | 31 (84) | 15 (79) | 0.30 |
| Any shared epitope alleles, n (%) | 122 (70) | 79 (67) | 30 (81) | 14 (74) | 0.79 |
| DAS28-CRP | 3.7 (2.9–4.4) | 3.6 (2.9–4.3) | 3.5 (2.8–4.5) | 3.8 (3.3–4.3) | 0.68 |
| CRP, mg/L | 2.4 (1.1–7.7) | 2.1 (1.0–7.1) | 3.5 (1.5–9.5) | 2.0 (1.6–5.4) | 0.65 |
| IL-6, pg/mL | 3.7 (1.8–7.8) | 3.6 (1.7–8.1) | 3.9 (1.8–6.3) | 3.7 (2.4–9.0) | 0.24 |
| Total SHS | 8 (1–37) | 5 (0–19) | 12 (2–43) | 56 (14–132) | <0.001 |
| Pain (100 mm VAS) | 21 (9–41) | 21 (8–40) | 23 (10–41) | 20 (5–47) | 0.71 |
| HAQ-DI (0–3) | 0.63 (0.12–1.25) | 0.63 (0.12–1.25) | 0.75 (0.12–1.25) | 0.75 (0–1.88) | 0.73 |
| Current prednisone, n (%) | 67 (38) | 45 (38) | 13 (35) | 9 (47) | 0.41 |
| Current non-biologic DMARDs, n (%) | 150 (86) | 100 (84) | 34 (92) | 16 (84) | 0.99 |
| Methotrexate, n (%) | 114 (65) | 79 (66) | 22 (59) | 13 (68) | 0.83 |
| Leflunomide, n (%) | 19 (11) | 11 (9) | 5 (14) | 3 (16) | 0.41 |
| Current biologic DMARDs, n (%) | 81 (46) | 55 (46) | 17 (46) | 10 (53) | 0.63 |
| TNF inhibitors, n (%) | 78 (45) | 52 (44) | 17 (46) | 10 (53) | 0.62 |
| Number of failed DMARDs | 1 (0–2) | 1 (0–2) | 1 (0–3) | 2 (0–2) | 0.75 |
Values are mean ± standard deviation or median (interquartile range) unless otherwise noted.
*p-values are for the comparison of the no anti-PAD vs. anti-PAD3/4XR groups.
PAD = peptidyl-arginine deiminase; anti-PAD3/4XR = anti-PAD3/4 Cross-Reactive antibodies; RA = rheumatoid arthritis; RF = rheumatoid factor; CCP2 = 2nd generation anti-cyclic citrullinated peptide antibody; DAS = disease activity score; CRP = C-reactive protein; IL = interleukin; SHS = Total modified Sharp-van der Heijde Score; HAQ = Health Assessment Questionnaire Disability Index; TNF = tumor necrosis factor; DMARD = disease modifying anti-rheumatic drug.