Table 5.
Baseline characteristics of subjects who provided blood sample, by risk-subgroups, SCREEN-RA cohort, Switzerland, 2009–2020
| Variables (at enrolment) | Low risk | High risk | ||||||
| Mean (SD) | Mean (SD) | P value (ANOVA or χ2) | ||||||
| Otherwise n (%) | Otherwise n (%) | |||||||
| Risk groups (total n=1458): | NA (n=31) | 1 (n=1006) | 2 (n=80) | 3 (n=147) | 4 (n=143) | 5 (n=51) | ||
| Not assigned (serological result awaited) | Asymptomatic without specific autoimmunity | High genetic risk without specific autoimmunity | Asymptomatic with specific autoimmunity | Isolated clinically suspect arthralgias | Clinically suspect arthralgia with specific autoimmunity or high genetic risk | |||
| Variables | ||||||||
| Demographics | Age (years) | 42 (12) | 43 (14) | 44 (12) | 45 (15) | 50 (14) | 48 (13) | <0.001 |
| Gender (female) | 68% | 72% | 78% | 75% | 86% | 84% | 0.004 | |
| White ethnicity | 84% | 92% | 88% | 90% | 91% | 82% | 0.044 | |
| BMI | 27 (6) | 24 (4) | 24 (4) | 24 (4) | 25 (5) | 26 (5) | 0.02 | |
| Tobacco smoking | 0.22 | |||||||
| current | 29% | 18% | 28% | 16% | 24% | 20% | ||
| previous | 26% | 25% | 33% | 31% | 26% | 24% | ||
| never | 29% | 51% | 29% | 51% | 48% | 56% | ||
| Biology | ACPA seropositivity (commercial or non-commercial assays) | 0% | 0% | 42% | 0% | 31% | <0.01 | |
| RF seropositivity (IgA or IgM) | ||||||||
| at least 1 × ULN | 12% | 9% | 66% | 17% | 53% | <0.01 | ||
| at least 3 × ULN | 0% | 0% | 61% | 0% | 43% | |||
| Anti-RA33 antibodies | 0% | 0% | 3% | 1% | 2% | 0.02 | ||
| (3 × ULN) | ||||||||
| HLA-SE | <0.01 | |||||||
| 0 copy | 55% | 0% | 52% | 54% | 35% | |||
| 1 copy | 43% | 0% | 39% | 43% | 27% | |||
| 2 copies | 0% | 100% | 7% | 0% | 27% | |||
| Undifferentiated arthritis | 0% | 0% | 0% | 0% | 11% | 6% | <0.01 | |
‘Highgenetic risk’ defined as having two copies of the HLA-SE. ‘Undifferentiatedarthritis’ means : presence of clinically suspect arthralgia + a least oneswollen joint (patient reported or nurse examined). P values computed excludingthe NA group.
ACPA, anticitrullinated peptide antibodies; ANOVA, analysis of variance; BMI, body mass Index; CCP, cyclic citrullinated peptide; HLA-SE, human leucocyte antigen shared epitope allele; SCREEN-RA, Evaluation of a SCREENing strategy for Rheumatoid Arthritis; ULN, upper limit of the norm.