Table 1.

Baseline clinical characteristics of 585 primary SS patients

	All (n = 585)	ACA alone (n = 22)	SSA alone (n = 464)	Double-positive (n = 26)	Seronegative (n = 73)	p value
Mean age, years	55 ± 15	63 ± 11	54 ± 16	60 ± 11	61 ± 13	< 0.001
Female, n (%)	547, 94%	21, 95%	436, 94%	26, 100%	64, 88%	0.10
Dry mouth, n (%)	523, 90%	19, 86%	412, 89%	23, 88%	69, 95%	0.50
Dry eyes, n (%)	451, 77%	13, 59%	362, 78%	21, 81%	55, 75%	0.19
Raynaud’s phenomenon, n (%)	46, 8%	6, 27%	30, 6%	9, 35%	1, 1%	< 0.001
Sclerodactyly, n (%)	30, 5%	9, 41%	12, 3%	7, 27%	2, 3%	< 0.001
Lymphadenopathy, n (%)	38, 7%	0, 0%	31, 7%	2, 8%	5, 7%	0.64
Extraglandular involvement, n (%)	405, 69%	4, 18%	351, 76%	18, 69%	32, 44%	< 0.001

Presented as mean and standard deviation. The Kruskal–Wallis test was used to assess the statistical significance of differences between groups

ACA anti-centromere antibody, SSA anti-SS-A antibody