Anti-cyclic citrullinated peptide antibody titer predicts time to rheumatoid arthritis onset in patients with undifferentiated arthritis: results from a 2-year prospective study

Table 3 Baseline demographic, clinical and serological characteristics of the 192 patients subdivided according to diagnosis after 24 months

Parameter at onset	Patients developing RA		Patients not developing RA		P
	Number	%	Number	%
Patients	72	37.5	120	62.5
Age, years, mean ± SD	52 ± 16	na	52 ± 15	na	0.895
Female	57	79.2	90	75.0	0.628
Monoarthritis	7	9.7	11	9.2	0.999
Oligoarthritis	16	22.2	41	34.2	0.111
Polyarthritis	49	68.1	68	56.6	0.158
Hand joints arthritis	55	76.4	71	59.2	0.023
CRP+	41	56.9	58	48.3	0.314
CRP ratio, median (IR)	1.9 (0.6-1.9)		0.9 (0.6-2.6)		0.031
ESR increase	38	52.8	65	54.2	0.970
ESR median (IR)	24 (12.3-53.3)		22.5 (16.0-38)		0.773
RF+	45	62.5	34	28.3	< 0.0001
RF ratio, median (IR)	2.3 (0.6-7.8)		0.6 (0.5-1.2)		< 0.0001
RF low+/total RF+	11	24.4	15	44.1	0.109
RF high+/total RF+	34	75.5	19	55.9
ACPA+	53	73.6	27	22.5	< 0.0001
ACPA ratio, median (IR)	5 (0.6-14.3)		0.5 (0.3-0.8)		< 0.0001
ACPA low+/total+	7	13.2	6	22.2	0.476
ACPA high+/total+	46	86.8	21	77.8
RF+/ACPA-	2	2.8	12	10	0.115
RF-/ACPA+	10	13.9	5	4.2	0.031
RF+/ACPA+	43	59.7	21	18.3	< 0.0001
RF-/ACPA-	17	23.6	81	67.5	< 0.0001

RA, rheumatoid arthritis; CRP, C-reactive protein; IR, interquartile range; ESR, erythrocyte sedimentation rate; RF, rheumatoid factor; ACPA, anti-citrullinated peptide antibodies; NA, not applicable.

ISSN: 1478-6362