Table 3.

Multivariable model of predictors of time to HIV transmission among Zambian women and men in HIV discordant relationships

Primary modela,b	M+F- couples				F+M- couples
Exposures of interest	aHR	95% CI		P-value	aHR	95% CI		P -value
Genital inflammation of woman
STI	1.36	0.76	2.43	0.30	1.01	0.50	2.05	0.97
Non-STI	1.55	1.01	2.38	0.04	1.92	1.15	3.22	0.01
No	ref				ref
BIA of woman
Yes	2.33	1.43	3.81	< 0.01	2.76	1.69	4.51	< 0.001
No	ref				ref
Genital ulcer of woman
Yes	2.08	1.27	3.41	< 0.01
No	ref
Genital inflammation of man
STI	3.33	1.79	6.17	< 0.01		e
Non-STI	1.18	0.43	3.21	0.75	1.19	0.51	2.77	0.69
No	ref				ref
BIA of man
Yes	3.35	2.24	5.03	< 0.001	4.11	2.52	6.72	< 0.001
No	ref				ref
Genital ulcer of man
Yes	1.49	1.05	2.11	0.03	3.44	2.20	5.38	< 0.001
No	ref				ref
Baseline and time-varying variables
Age of woman (per year increase)	0.98	0.95	1.00	0.04	0.99	0.96	1.02	0.42
Woman reads Nyanja
Yes, easily	ref
With difficulty/not at all	1.22	0.82	1.80	0.32
Circumcised manc
Yes					ref
No					2.10	1.12	3.95	0.02
VL of positive partner (per log10 copies/ml increase)	1.68	1.35	2.08	< 0.001	1.80	1.44	2.23	< 0.001
Any self-reported unprotected sex with study partner since last visit
Yes	1.38	1.01	1.88	0.04	1.91	1.33	2.75	< 0.01
No	ref				ref
Sperm present on vaginal swab wet mount
Yes	1.41	0.88	2.26	0.15	1.73	1.03	2.91	0.04
No	ref				ref
Current pregnancy
Yes					1.35	0.79	2.31	0.27
No					ref
Interval since enrolment
0–3 months	4.30	2.75	6.72	< 0.001	5.07	2.93	8.78	< 0.001
< 3 months	ref				ref
Pre-2002 model 1d
Circumcision and smegma status
Circumcised	ref				ref
Uncircumcised and no smegma	1.68	0.93	3.04	0.08	4.50	2.36	8.59	< 0.001
Uncircumcised and smegma	3.16	1.54	6.46	< 0.01	8.59	3.72	19.86	< 0.001
Pre-2002 model 2d
Circumcision status and smegma by man's BIA
Circumcised
BIA of man: Yes					0.36	0.06	1.99	0.24
BIA of man: No					ref
Uncircumcised and no smegma
BIA of man: Yes					4.95	2.43	10.10	< 0.001
BIA of man: No					0.85	0.31	2.34	0.75
Uncircumcised and smegma
BIA of man: Yes					13.03	4.97	34.17	< 0.0001
BIA of man: No						e

Foreskin smegma recorded from 1994-2002. P-values are two-tailed from Cox models. Adjusted point estimate for genital ulcer of woman in F+M- primary model (not included in final models): aHR = 0.94, 95% CI:0.55-1.62 (P = 0.84).

^a‘Generalized’ R-squared = 0.63 for M+F- couples (primary model).

^b‘Generalized’ R-squared = 0.80 for F+M- couples (primary model).

^cCircumcised at baseline or ever during follow-up.

^dControlling for the primary model variables.

^eSmall sample size; a measure of association could not be estimated.