Table 1.
Characteristics of the different patient subsets
| IMPROVED seropositivea RA | IMPROVED seronegative RA | IMPROVED seropositive, RF IgA-/CCP2 IgA- RA | EAC seropositivea RA | EAC seronegative RA | Healthy donors | |
|---|---|---|---|---|---|---|
| Number | 125 | 56 | 68 | 95 | 64 | 60 |
| Time sampling | Baseline | Baseline | Baseline | 1 -year visit | 1-year visit | NA |
| Age, mean (s.d.), years | 53.3 (12.4) | 54.3 (15.1) | 47.1 (14.7) | 59.1 (15.3) | 59.1 (16.8) | 44.7 (14.4) |
| Female, n (%) | 80 (64) | 39 (70) | 48 (71) | 64 (67)b | 41 (64)b | 35 (58) |
| Ever smoking, n (%) | 76 (61) | 23 (42) | 18 (27) | 50 (53)b | 22 (35)b | Unknown |
| CRP, mg/L, mean (s.d.) | 24.5 (34.1) (n = 120) | 22.2 (32.3) (n = 55) | 25.3 (33.0) (n = 64) | 26.3 (37.7) (n = 75) |
11.0 (21.8) (n = 55) |
NA |
| DAS, mean (s.d.) | 3.29 (0.91) | 3.70 (0.85) | 3.20 (0.83) | Unknown | Unknown | NA |
| RF IgM positivity, n (%) | 112 (92) | 0 0 | 56 (85) | 75 (79)b | 0 0b | NA |
| RF IgA positivity, n (%) | 106 (85) | NA | 0 0 | Unknown | NA | NA |
| Anti-CCP2 IgG positivity, n (%) | 118 (95) | 0 0 | 38 (57) | 95 (100)b | 0 0b | NA |
| Anti-CCP2 IgA positivity, n (%) | 102 (82) | NA | 0 0 | 63 (67)b | NA | NA |
| Total IgA1, μg/ml, median (IQR) | 3082 (2057–4579) | 1581 (1273–2155) | 2913 (1968–3912) | 2936 (2229–3828) | 2605 (2215–3259) | 1720 (1280–2338) |
| Total IgA2, μg/ml, median (IQR) | 221 (145–433) | 134 (65–328) | 197 (139–400) | 153 (95–356) | 196 (74–473) | 127 (86–188) |
| % IgA2 total IgA, median (IQR) | 7.9 (4.7–11.4) | 8.0 (3.8–15.3) | 6.0 (4.5–9.2) | 5.2 (3.2–11.7) | 6.7 (2.9–18.3) | 6.7 (4.8–9.6) |
a
Enriched for ACPA IgA positivity.
b
Information collected at baseline.