Table 1. Summary statistics of SS phenotypes, potential confounders, and co-morbidities.

	cases (n = 64)	non-cases (n = 67)	p-value
Focus score	3.39 (1.83)	0.89 (0.67)	6.80E-6
Left ocular staining score	7.46 (2.91)	3.19 (2.75)	8.54E-12
Right ocular staining score	7.19 (3.17)	3.25 (2.74)	4.21E-10
SSA seropositive (indicator)	0.63	0	3.61E-14
SSB seropositive (indicator)	0.55	0	6.26E-12
Unstimulated whole salivary flow rate	0.34 (0.39)	0.70 (0.54)	8.20E-6
Schirmer ≤ 5 mm/5min on at least one eye	0.23	0.07	2.16E-2
Self-reported age of SS onset at screening	49.12 (10.80)	46.10 (8.86)	2.04E-1
Censored age at study visit	54.69 (11.94)	53.46 (10.82)	4.53E-1
Current smoker	0.01	0.06	3.90E-1
Anticholinergic drug use	0.40	0.51	2.76E-1
SLE suspected	0	0	NA
SLE physician confirmed	0.05	0.04	1.00
RA suspected	0	0.01	1.00
RA physician confirmed	0.06	0.03	6.34E-1

Means and corresponding standard deviations (in parenthesis) are reported for continuous variables, and proportions are reported for binary variables. The p-value reports significance of difference between cases and non-cases for a given variable, determined either with Wilcoxon’s rank sum test for continuous variables or chi-square test of independence for binary variables. Missing values are excluded from summary statistics. NA = not available; SLE = systemic lupus erythematosus; RA = rheumatoid arthritis.