Table 2.

Univariable analysis of baseline antibody levels ✕ chlamydia infection status indicates increased risk for incident infection in women who were uninfected at enrollment.

Interaction term	Description	Unadjusted		Adjusted*
		Estimated HR# (95% CI)	P value**	Estimated HR (95% CI)	P value**
Serum anti-EB IgG × chlamydia infection status	Uninfected	3.31 (1.20 , 9.15)	ref***	3.63 (1.28 , 10.34)	ref
	Endo-	1.04 (0.64 , 1.69)	0.044	0.90 (0.51 , 1.56)	0.020
	Endo+	0.85 (0.46 , 1.59)	0.026	0.98 (0.51 , 1.9)	0.038
Serum anti-EB IgA × chlamydia infection status	Uninfected	0.88 (0.4 , 1.93)	ref	0.89 (0.46 , 1.74)	ref
	Endo-	1.23 (0.89 , 1.69)	0.441	1.02 (0.72 , 1.45)	0.735
	Endo+	0.77 (0.36 , 1.66)	0.821	0.90 (0.42 , 1.95)	0.983
Cervical anti-EB IgG × chlamydia infection status	Uninfected	19.54 (3.17 , 120.54)	ref	22.57 (3.08 , 165.16)	ref
	Endo-	0.85 (0.59 , 1.22)	0.001	1.05 (0.69 , 1.6)	0.003
	Endo+	1.13 (0.57 , 2.21)	0.004	1.27 (0.61 , 2.65)	0.007
Cervical anti-EB IgA × chlamydia infection status	Uninfected	1.16 (0.50 , 2.68)	ref	1.13 (0.45 , 2.85)	ref
	Endo-	1.07 (0.70 , 1.65)	0.877	1.22 (0.78 , 1.9)	0.890
	Endo+	0.97 (0.58 , 1.63)	0.733	0.98 (0.56 , 1.7)	0.790

^#HR: hazard ratio. Each value represents the fold-change in incident infection risk for each unit increase in log10 anti-EB antibody/total antibody

^*Adjusted for age, gonorrhea, and sex with new, uncircumcised, or infected partners.

^**P value indicates the statistical comparison of the effect of antibody on incident infection between the various groups, with uninfected women as the reference group.

^***ref: Reference level