Table 1. Characteristics of patients with type 1 (autoantibody-positive) and type 2 (autoantibody-negative) RA at first presentation to the Leiden Early Arthritis Clinic.
| Characteristic | Inclusion period | p-Value | ||||
|---|---|---|---|---|---|---|
| 1993–1996 | 1997–2000 | 2001–2005 | 2006–2010 | 2011–2016 | ||
| Type 1 RA | (n = 112, 67%) | (n = 118, 64%) | (n = 129, 62%) | (n = 203, 61%) | (n = 261, 67%) | |
| Women, n (%) | 77 (69) | 82 (70) | 91 (71) | 136 (67) | 167 (64) | 0.70 |
| Age in years, mean (SD) | 56 (16) | 55 (16) | 55 (15) | 54 (15) | 56 (15) | 0.63 |
| Symptom duration, days, median (IQR) | 153 (84–306) | 156 (84–304) | 147 (72–264) | 146 (61–270) | 103 (53–227) | 0.006 |
| Current smoker, n (%) | 35 (33) | 35 (33) | 29 (27) | 40 (22) | 74 (30) | 0.21 |
| 28 SJC, median (IQR) | 6 (3–10) | 7 (4–12) | 4 (2–7) | 4 (2–7) | 4 (2–7) | <0.001 |
| 28 TJC, median (IQR) | 7 (3–13) | 7 (3–14) | 7 (3–12) | 6 (3–11) | 5 (2–9) | <0.001 |
| ESR, median (IQR) | 46 (26–70) | 32 (20–54) | 30 (18–55) | 29 (14–42) | 29 (14–41) | <0.001 |
| VAS general health, median (IQR) | 43 (17–70) | 44 (26–66) | 53 (34–72) | 56 (29–72) | 70 (50–80) | <0.001 |
| DAS28-ESR, median (IQR) | 5.5 (4.2–6.5) | 5.2 (4.2–6.1) | 5.2 (4.3–6.0) | 4.9 (4.2–6.0) | 4.8 (4.1–5.7) | 0.02 |
| HAQ, median (IQR) | 1.0 (0.6–1.4) | 0.8 (0.4–1.6) | 1.0 (0.6–1.6) | 1.0 (0.5–1.5) | 1.0 (0.5–1.5) | 0.12 |
| Type 2 RA | (n = 56, 33%) | (n = 67, 36%) | (n = 78, 38%) | (n = 132, 39%) | (n = 129, 33%) | |
| Women, n (%) | 38 (68) | 41 (61) | 57 (73) | 80 (61) | 79 (61) | 0.34 |
| Age in years, mean (SD) | 56 (15) | 59 (19) | 60 (14) | 61 (16) | 62 (14) | 0.16 |
| Symptom duration, days, median (IQR) | 126 (61–220) | 92 (62–219) | 120 (74–234) | 109 (59–176) | 85 (45–189) | 0.06 |
| Current smoker, n (%) | 17 (30) | 11 (18) | 14 (20) | 24 (21) | 28 (22) | 0.52 |
| 28 SJC, median (IQR) | 9 (4–14) | 12 (7–19) | 6 (3–10) | 6 (3–10) | 6 (3–10) | <0.001 |
| 28 TJC, median (IQR) | 9 (3–19) | 13 (6–20) | 11 (5–19) | 9 (4–13) | 7 (3–11) | <0.001 |
| ESR, median (IQR) | 40 (22–56) | 28 (16–47) | 27 (16–47) | 31 (9–46) | 25 (11–41) | 0.008 |
| VAS general health, median (IQR) | 46 (25–63) | 50 (26–62) | 56 (36–75) | 64 (44–79) | 70 (60–80) | <0.001 |
| DAS28-ESR, median (IQR) | 5.6 (4.5–6.3) | 5.8 (4.8–6.5) | 5.6 (4.4–6.7) | 5.3 (4.4–6.3) | 5.2 (4.4–6.0) | 0.19 |
| HAQ, median (IQR) | 1.1 (0.8–1.6) | 0.9 (0.5–1.4) | 1.1 (0.8–1.8) | 1.1 (0.8–1.5) | 1.0 (0.6–1.5) | 0.15 |
p-Value for results of Kruskal–Wallis H test (Fisher’s exact test for proportions and ANOVA for normally distributed variables). The percentage of patients with type 1 or 2 RA for the different inclusion periods was stable over time (p = 0.42). SJC and TJC are the number of swollen and tender joints, respectively, out of 28 joints assessed. The VAS general health is a self-reported assessment, ranging from 0 to 100. DAS28-ESR ranges from 2 to 9.4, with higher scores indicating more disease activity. HAQ (HAQ Disability Index) ranges from 0 to 3, with higher scores indicating more disability.
DAS28-ESR, Disease Activity Score–28 with erythrocyte sedimentation rate; ESR, erythrocyte sedimentation rate; HAQ, Health Assessment Questionnaire; IQR, interquartile range; RA, rheumatoid arthritis; SD, standard deviation; SJC, swollen joint count; TJC, tender joint count; VAS, visual analogue scale.