Table 4.
Baseline biological and physical characteristics of participants, SCREEN-RA cohort, Switzerland, 2009–2020
| Variable | No (%) (total n=1458) | |
| BMI groups | <18 | 30 (2) |
| 18 to <25 | 892 (61) | |
| 25 to <30 | 385 (27) | |
| ≥30 | 127 (9) | |
| Missing | 24 (2) | |
| Biology | Provided at least two blood samples | 412 (28) |
| Total ACPA seropositivity (commercial or non-commercial assays) | 78 (5) | |
| Total RF seropositivity | 282 (19) | |
| IgA RF seropositivity | 66 (5) | |
| IgM RF seropositivity | 251 (17) | |
| Total anti-Ra33 tested | 660 (45) | |
| Anti-Ra33 seropositivity (for any Ig subtype,≥3 × ULN) | 8 (0.5) | |
| Shared epitope allele no | 0 copy | 724 (50) |
| 1 copy | 564 (39) | |
| 2 copies | 105 (7) | |
| Not tested | 65 (4) | |
RA-converter subjects.
ACPA, anticitrullinated peptide antibodies; BMI, body mass index; RA, rheumatoid arthritis; RF, rheumatoid factors; SCREEN-RA, Evaluation of a SCREENing strategy for Rheumatoid Arthritis; ULN, upper limit of the norm.