Table 2.

The 2 × 2 analyses [9] of the data in Table 1

Test	Comparison	a	b	c	d	Odds ratio	Fisher's P value
DQA-RA		179	58	146	160	3.4	3E-11
association
SE association		172	65	127	179	3.7	3E-13
DQA-RA association
in SE-positive	++ vs -+	172	0	127	0	ND	ND
DQA-RA association
in SE-negative	+- vs--	7	58	19	160	1.1	NS
SE association in
DQ-RA-positive	++ vs +-	172	7	127	19	3.5	0.0024; pc = 0.029
SE association in
DQ-RA-negative	-+ vs--	0	58	0	160	ND	ND

ND, Not defined; NS, not significant; Pc, corrected P value; a and b, numbers of patients with and without marker in question; c and d, numbers of controls with and without marker in question.