Anti-Sa antibodies and antibodies against cyclic citrullinated peptide are not equivalent as predictors of severe outcomes in patients with recent-onset polyarthritis

Table 4 Odds ratio estimates of severe arthritis at 30 months from independent variables present at inclusion

Variable at presentation	Odds ratio estimate (95% confidence limits)
	Model A	Model B	Model C
RF ≥ 40 IU/ml	1.788 (0.549–5.825)	2.946 (0.957–9.073)	2.110 (0.715–6.231)
Anti-CCP ≥ 20 U/ml	0.320 (0.075–1.357)	0.917 (0.285–2.953)	-
Anti-Sa-positive	8.832 (2.141–36.436)***	-	-
Anti-CCP ≥ 60 U/ml	-	-	1.693 (0.551–5.201)
Age (per year)	1.063 (1.025–1.102)***	1.049 (1.015–1.084)***	1.048 (1.014–1.084)***
Male sex	1.741 (0.718–4.223)	1.627 (0.703–3.767)	1.700 (0.733–3.945)
Disease duration	1.686 (0.701–4.058)	1.647 (0.715–3.793)	1.603 (0.700–3.673)
Morning stiffness	0.415 (0.154–1.118)	0.554 (0.218–1.406)	0.502 (0.196–1.284)
Symmetry of arthritis	0.798 (0.174–3.657)	1.085 (0.241–4.880)	1.315 (0.282–6.124)
Swollen joint count	0.985 (0.940–1.033)	0.989 (0.946–1.033)	0.988 (0.945–1.033)
M-HAQ ≥ 1.0	0.666 (0.266–1.666)	0.750 (0.315–1.789)	0.791 (0.330–1.897)
CRP ≥ 8 mg/L	2.594 (0.920–7.312)	2.107 (0.795–5.581)	2.139 (0.807–5.667)
HLA shared epitope	1.096 (0.444–2.704)	0.982 (0.417–2.313)	0.937 (0.401–2.186)
Erosion SvH score	3.472 (1.236–9.575)*	3.751 (1.388–10.135)*	3.611 (1.340–9.729)**

Multivariate regression analysis was performed using all three autoantibodies (model A), without anti-Sa (model B), and without anti-Sa but with a higher threshold of 61 U/ml for anti-cyclic citrullinated peptide (anti-CCP) (model C). Confidence limits are 95% Wald confidence limits. Disease duration was set as positive when present for at least 4 months. Morning stiffness was set as positive when it lasted for at least 60 min. The swollen joint count represents the contribution of each additional joint above the inclusion requirement of three. HLA shared epitope indicates the presence of at least one of the HLA DR alleles associated with RA, as listed in the Methods section. Erosion Sharp–van der Heijde (SvH) score was set as positive when the value was 5 or more. CRP, C-reactive protein; M-HAQ, modified Health Assessment Questionnaire; RF, rheumatoid factor. *P < 0.02; **P < 0.01; ***P < 0.005.

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