Table 2

Arthritis development is associated with ACPA status and levels: univariate analyses

Arthritis (n = 29)No arthritis (n = 118)HR (95% CI)
Qualitative
ACPA, n (%)26 (90)69 (58)6.0 (1.8 to 19.8)
IgM-RF, n (%)21 (72)76 (64)1.4 (0.6 to 3.1)
SE, n (%)13 (45)41 (35)1.5 (0.7 to 3.0)
Quantitative
ACPA levels*141 (21–304)31 (11–100)1.7 (1.1 to 2.5)
IgM-RF levels*72 (39–119)56 (39–117)1.2 (0.8 to 1.7)
  • * Median (interquartile range) of positive patients only; for Cox regression analyses, positive ACPA (AU/ml) and IgM-RF (IU/ml) levels were divided into quartiles and entered as continuous variables. The associated hazard ratio can be interpreted as mean hazard ratio of the first quartile versus the second, the second versus the third, etc.

  • ACPA, anti-citrullinated protein antibodies; 95% CI, 95% confidence interval; HR, hazard ratio; RF, rheumatoid factor; SE, shared epitope.