Table 2.
Clinical characteristics of at-risk individuals in the validation cohort
| At-risk individuals no arthritis developed (n=35) | At-risk individuals arthritis developed (n=15) | |
| Female sex, n (%) | 22 (63) | 8 (53) |
| Age, years, median (IQR) | 51 (43–55) | 47 (37–52) |
| IgM-RF positive, n (%) | 28 (80) | 11 (73) |
| Level low positive, n (%)*† | 20 (57) | 7 (64) |
| Level high positive, n (%)*† | 15 (43) | 4 (36) |
| ACPA positive, n (%) | 20 (57) | 14 (93) |
| Level, median (IQR)*‡ | 1333 (364–9650) | 342 (155–1016) |
| IgM-RF/ACPA double positive, n (%) | 13 (37) | 10 (67) |
| ESR, median (IQR)§ | 12 (4–18) | 10 (3–19) |
| CRP, median (IQR)¶ | 2.4 (0.9–4.5) | 2.3 (1.1–9.4) |
| 53TJC, median (IQR) | 0 (0–0) | 0 (0–1) |
| Risk rule model** | ||
| Low risk, n (%) | 17 (49%) | 0 (0%) |
| Intermediate risk, n (%) | 14 (40%) | 6 (40%) |
| High risk, n (%) | 4 (11%) | 9 (60%) |
Positive IgM-RF: >12.5 kU/L.
Positive anti-CCP2 >25 kAU/L.
*Only in individuals who were positive.
†Levels were categorised into high/low positive according to cut-off levels used in the 2010 ACR/EULAR criteria for rheumatoid arthritis because of changed reference values over time.
‡Measured in kAU/L.
§Measured in mm/hour.
¶Measured in mg/L.
**Score based on the risk rule24 scaled 0–13 points.
ACPA, anticyclic citrullinated peptide antibodies (using anti-CCP2 test); CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; IgM-RF, rheumatoid factor of the IgM isotype; 53TJC, tender joint count assessed in 53 joints.