Table 1.

Characteristics of the study population

	Transmitting couples, N=121		Non-transmitting couples, N=501		Subtype C***, N=217		Non-C Subtypes***, N=362
	N/median	%/IQR	N/median	%/IQR	N/median	%/IQR	N/median	%/IQR
Demographic characteristics
HIV-1 infected female	60	49.6%	328	65.5%	149	68.7%	208	57.5%
Age in years, HIV-1 infected partner	30	26–35	32	26–38	32	27–39	30	26–37
East African (vs. southern African)	80	66.1%	332	66.3%	25	11.5%	353	97.5%
Married/living together	113	93.4%	459	91.6%	179	82.5%	353	97.5%
Duration of partnership, years	3.8	1.5–7.0	5	2.2–9.7	4.1	1.8–8.7	5.2	2.2–9.6
Number of children within partnership	1	0–2	1	0–2	1	0–2	1	0–2%
Unprotected sex
One month prior to enrollment	56	52.8%	160	36.2%	81	37.3%	125	34.5%
Follow-up visits with unprotected sex**	220/1057	20.8%	643/9280	6.9%	411/3365	12.2%	420/6168	6.8%
Antiretroviral therapy initiated during follow-up	1	0.8%	67	13.4%	6	2.8%	54	14.9%
Baseline clinical characteristics
CD4 count, cells/mm3	417	302–580	434	341–601	418	316–570	428	332–602
HIV-1 plasma viral load, log10 copies/mL	4.8	4.3–5.1	4.2	3.6–4.8	4.2	3.7–4.8	4.4	2.9–4.0
Any genital tract infection (either partner)*	23	20.4%	74	15.9%	51	23.5%	43	11.9%
Circumcision (male HIV-1 uninfected partners)	39	65.0%	239	72.9%	84	38.7%	175	48.3%

^*Includes Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis

^**Numerator=all followup visits with unprotected sex reported, denominator=total follow-up visits

^***Subtype data shown for env; gag results were similar (N=43 without subtype information)

IQR=interquartile range

Bold indicates statistical significan at the p<0.05 level, comparing transmitting to non-transmitting couples and subtype C to non-C subtypes